n-252

March 16, 2018 | Author: miguelgg78 | Category: Electrical Substation, Transformer, Relay, Switch, Fuse (Electrical)
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PDVSAMANUAL DE INGENIERIA DE DISEÑO VOLUMEN 4–I ENGINEERING SPECIFICATION PDVSA N° TITULO N–252 GENERAL SPECIFICATION FOR ELECTRICAL ENGINEERING DESIGN 0 REV. JUL.96 FECHA APROBADO DESCRIPCION FECHA JUL.96 33 L.T. E.J. A.N. PAG. REV. APROB. Alejandro Newski APROB. APROB. FECHA JUL.96 APROB. Eliecer Jiménez E1994 ESPECIALISTAS ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA .Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL.96 Página 1 Indice norma Index 1 GENERAL DESIGN AND ENGINEERING PRINCIPLES . . . . . . . . . 1.1 1.2 1.3 1.4 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Codes and Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Safety , Reliability and Energy Conservation . . . . . . . . . . . . . . . . . . . . . . . . Basic Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . System Voltages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Variations In Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . System Power Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Supply Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Short Circuit Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electrical Protection And Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . System Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electricity Supply Facilities for Process Control and Safeguarding Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 2 4 7 2 ELECTRICAL SYSTEM DESIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 8 8 8 9 9 10 10 14 15 3 DESIGN AND SELECTION REQUIREMENTS FOR EQUIPMENT, CABLES AND INSTALLATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.1 4.2 Switchgear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Transformers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electric Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cables And Wires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Power and Convenience Outlets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Metering Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Substations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mandatory Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 16 19 21 23 25 25 26 26 27 4 SUBSTATION FIRE PROTECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 28 28 5 POWER SUPPLY UNITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 ECONOMICAL EVALUATION OF LOSSES . . . . . . . . . . . . . . . . . . . . 7 DOCUMENTS AND DRAWINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 30 30 ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA .Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL.96 Página 2 Indice norma 1 GENERAL DESIGN AND ENGINEERING PRINCIPLES 1.1 Scope This general specification covers the minimum technical requirements for electrical engineering design, electrical area classification, grounding and lighting systems for oil and petrochemical plants owned by PDVSA. 1.2 Definitions Shall. Is to be understood as mandatory Owner. Party which initiates the project and ultimately pays for its design and construction. Contractor. Party which carries all or part of the design, engineering, procurement, construction and commissioning for the project. Low Voltage. Less than 1 000 V (Defined by ANSI C 84.1). Medium Voltage. 1 000 V and less than 100 000 V High Voltage. Equal to or greater than 100 000 V. Vital Service. A service, which, when failing, can cause an unsafe condition of the process and/or electrical installation, jeopardize life, or cause major damage to the installation. Essential Service. A service, which, when failing, will affect the continuity, the quality or the quantity of the product. Certificate Document issue by a recognised authority certifying that it has examined a certain type of apparatus and, if necessary, has tested it and concluded that the apparatus complies with the relevant standard for such apparatus. A station for connection between a power or distribution system of a process unit and an outside electrical supply system. The installed capacity less the stand–by capacity. The equipment is protected by a weather proof enclosure (standard outdoor construction). Tropicalized Preparation of equipment or apparatus to avoid the effects due to the tropical weather.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA .Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. . A station mainly used for feeding one process installation. installation and use of electrical apparatus Stand–by Capacity. A station mainly used for feeding several plant stations.96 Página 3 Indice norma Hazardous Area An area which an explosive atmosphere is or may be expected to be present in quantities such as to require special precautions for the construction. Plant Substation. Distribution Substation. A station to which generators and outgoing feeders are connected. Outdoor Substation. Firm Capacity. Capacity provided for the purpose of replacing that capacity which may be withdrawn from service under planned or unplanned circumstances. Spare Capacity. for the conversion or transformation of electrical energy and for connection between two or more circuits. Power Plant Substation. An assembly of equipment at one place. Station or Substation. including any necessary housing. A station which consists of indoor equipment within a field constructed building. Main Substation. Indoor Substation. Difference between firm capacity and the maximum calculated (peak) load. A. Spot Network Substation. it is the Contractor’s responsibility to ensure that Venezuelan Statutory requirements are met if these are more stringent than the references provided. in effect as of the latest edition.96 Página 4 Indice norma Secondary Selective Substation. Station having two busses. In the event of contradictions.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . The codes and specifications listed below. shall constitute minimum requirements: 1. GE–211 HA–201 JA–221 L–STE–017 L–STE–018 L–STE–019 L–STE–020 N–201 N–241 N–301 N–302 N–242 Q–211–PT Q–231 SD–251 IR–E–01 Electric Standby Generator Set–Engine Driven Cathodic Protection Diseño Antisísmico de Instalaciones Industriales Mechanical Coordination Electrical Design Drawings Procedures for Checking Electrical Design Drawings Electrical Estimating Procedure Electrical Work Installation of wires and Cables in Conduit and Cable Tray System Low Voltage Electrical Motors High Voltage Electrical Motors Electrical Work Installation and Testing Field Inspection for Transformers Reception Electrical Wire and Cable Testing Site Data Hazard Area Classification . each supplied by a normally closed incoming line circuit and connected together by a normally open bus–tie circuit breaker. Where international standards or codes of practice are referred to here in. A station supplied from two or more sources which normally divide the substation load in paralleled operation. S. 1.3 Codes and Standards The design and engineering of the electrical installation shall basically comply with the Venezuelan Codes.1 PDVSA – Petróleos de Venezuela. the requirements of this specification shall prevail.3.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. 3.064 1. with Load tap Changing – Safety Requirements Electric Power Systems and Equipment – Voltage Ratings (60 Hertz) Graphic Symbols for Electrical Wiring and Layout Diagrams National Electrical Code (National Fire Codes.00 C57.1 C.1 Y32.10 National Electrical Safety Code Standard Electrical Power System Device Function Numbers Application Guide for AC High – Voltage Cicuit Breakers Rated on an Symmetrical Current Basis. Iluminaciones en Tareas y Areas de Trabajo 603 734 2249 1. C 84.3.010 C.050 to .2 200 548 559 Separación entre Equipos e Instalaciones Engineering Design Guide – Electrical COVENIN – Comité Venezolano de Normas Industriales Venezuelan Código Eléctrico Nacional (similar to NEC / ANSI / NFPA – 70) Recomendaciones para clasificar las áreas destinadas a instalaciones eléctricas en refinerías de petróleo Recomendaciones para clasificar las áreas destinadas a instalaciones en los sistemas de tuberías para transportar petróleo y gas. Recomendaciones para clasificar las áreas destinadas a instalaciones eléctricas en instalaciones de producción petrolera Código Nacional de Seguridad de Instalaciones de Suministro de Energía Eléctrica y de Comunicaciones. vol.3 American Standards: ANSI – American National Standards Institute C2 C37. Transformers – 230 kV and Below 833/958 through 8333/10417 kVA.2 C57.37.20.3) Guide for Substation Fire Protection.12.37.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. Standard for Metal – Clad and Station – Type Cubicle Switchgear Standard General Requirements for Liquid Immersed Distribution.1.20. and 3750/4687 through 60000/80000/100000 kVA. Single–Phase.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA .9 70 979 .12. and Regulating Transformers. (Based on the National Electrical Safety Code ANSI C2). Standard for Metal – Enclosed Low Voltage Power Circuit Breaker Switchgear.2 C37. three–phase without Load tap Changing.96 Página 5 Indice norma IR–M–01 90619. and 750/862 through 60000/80000/100000 kVA. Power. 2 – April 1995 IEEE – Institute of Electrical and Electronics Engineers 519 Std. Revision No.3) AEIC – Associations of Edison Illuminating Commission CS5 1. vol.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . Revision No.3.1 – December 1993.96 Página 6 Indice norma NEMA – National Electrical Manufacturers Association MG–1 Motors and Generators. 841 Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems Standard for Petroleum and Chemical Industry – Severe Duty Totally Enclosed Fan Cooled (TEFC) Squirrel Cage Induction Motors – Up to and including 500 HP ICEA – Insulated Cable Engineers Association P–32–382 P–45–482 Short–Circuit Characteristics of Insulated Cable Short–Circuit Performance of Metallic Shielding & Sheaths API – American Petroleum Institute RP 500 Standard 541 Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Form – Wound Squirrel Cage Induction Motors – 250 Horse Power and Larger NFPA – National Fire Protection Association 70 National Electrical Code (National Fire Codes.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL.4 Specifications for Cross – Linked Polyethylene Insulated Shielded Power Cables Rated s Through 46 kV International Standard IEC – International Electrotechnical Commission 76 158 255 529 549 617 947 Power Tansformers Low Voltage Controlgear Single Input Energizing Quantity Measuring Relays with Dependent Specified Time Degrees of Protection Provided by Enclosures (IP Codes) High – Voltage Fuses for the External Protection of Shunt Power Capacitors Graphics Symbols for Diagrams Low – Voltage Switchgear and Controlgear . such as poly–chlorinated biphenyls (PCBs).7 1.3.3.4 1.3.3.1 Safety. shall be of the same manufacturer. inspections and maintenance. the recommendations of IEC shall govern for equipment manufactured outside of the USA. while ANSI and NEMA shall govern for equipment manufactured in the USA. Periodic energy audits shall be carried out to assure optimum results. The insulating and dielectric materials used in all electrical equipment shall be non–toxic and shall not contain compounds that are persistent and hazardous environmental contaminants. 1. manufactured and tested by the governing standards and regulations of the country of manufacture. including those associated with start–up and shutdown of plant and equipment. kW and equivalent HP shall be indicated. 1. this specification shall prevail. Where requirements contained in this specification are higher than those in the codes or standards referred to above.5 The Electrical equipment and material shall be designed.5 . Equipment incorporating similar or identical components and of similar or identical construction.2 1. The electrical design shall permit periods of continuous operation of at least 4 years. Electrical graphical symbols shall be per IEC–617.3.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL.4.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA .96 Página 7 Indice norma 1.9 1. Energy conservation shall be pursued throughout the design. or ANSI Y32.8 1.3 1.4 1. The SI unit system shall be used throughout the design. For motors.JA–221 . In general.6 1.4.4. Identification by device code letters and by device code numbers shall be per ANSI C37. Standardization of material and equipment shall be aimed.4. Reliability and Energy Conservation The electrical installation shall be designed and guaranteed to ensure personal and operational safety during all operating conditions.2. The equipment and electrical installation shall be tropicalized and suitable for the environment influences and climatic conditions as specified: – – – – – Altitude Humidity Ambient air temperature Atmosphere Sismic conditions: in accordance with PDVSA .4. API RP 500 and COVENIN 548.4. MV and LV switchgears.4. 2. showing the relevant physical properties of substances handled in every classified area. Where such equipment is not available.5. shall be prepared using document Engineering Design Guide PDVSA 90619.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. flow and volumen handled Fire detection and alarm shall conform to PDVSA “Risk Engineering Manual” and NFPA. and NEC. .ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . HV. the manufacturer’s test report in accordance with PDVSA specifications.7 1. flammable limits in percent by volume. shall be prepared for approval by owner’s engineer. 2. Section 3.3. 1.3 2. e. The former is based on. For all major equipment. 559 and 603. operating pressure.96 Página 8 Indice norma 1. which is required for classified locations. as far as possible. relative vapor density.1). its design shall conform to the standard of a nationally recognized testing organization. motors. Sections 3. transformers. Chap.8 1. 2 (IR–E–01).35. the Department of Trade and Industry (Great Britain). at least.4. range A. 5. electrical equipment shall.1 2. for generators.2 2. In general. Approved equipment. (See PDVSA N–201 .5. Control rooms and switch houses shall be situated in non–hazardous areas.4.1.1.3. A schedule of the installed electrical loads. expressed in kW and kVA. A table shall be included in the area classification drawing.050. as indicated in PDVSA N–201.6 Area classification drawings and electrical equipment selection shall conform to PDVSA–MIR Vol. 60 Hz operation at the voltages mentioned in Appendix A.28 up to 3. The minimum distance between equipment and installations shall be per PDVSA IR–M–01 “Separación entre Equipos e Instalaciones”. the maximum normal running plant load and the peak. or PTB (Germany).1 2.4.g. ignition temperature. batteries and inverter units.10 2 ELECTRICAL SYSTEM DESIGN 2.1 System Voltages Voltage ratings shall conform to ANSI C84.2.1. shall be labeled.9 1. the purchaser shall obtain. such as: flash point.2 Basic Information Single line diagrams and data. be located in non hazardous areas.1 Variations In Supply Voltage Terminal voltage and voltage drop shall be as indicated in PDVSA N–201.1. The electrical equipment shall be designed for 3–phase. listed or certified by a national recognized testing organization such as the Underwriter Laboratory (USA). – Starting or reacceleration of a motor or group motor starting/reacceleration: +10%.4 Equipment having special requirements with respect to variations in voltage level and/or wave form shall be provided with a power supply that is adequately stabilized. result in the instantaneous re–energization of vital and essential services. contactors fed from the UPS. – Voltage drop below 80% for a duration of not more than 0. averaged over 15 minutes. or any other measure to desensitize the critical loads.2 Voltage sags of short duration causing the drop–out of contactors and other sensitive loads.5 1.5 2. – Voltage drop below 80% for a duration of 0.0 1.0 5. usually affect the process continuity. on a voltage restoration.5 2. – Voltage drop to 80% shall not affect plant operations.5 69 – 138 kV > 138 kV 2. such as: automatic reacceleration and/or restarting of motors. The proposed limits are as follows: Harmonic voltage distortion in % < 69 kV Maximum for Individual harmonic Total harmonic 3.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA .5. shall be as follows: – Steady state conditions: –+ 5%. on a voltage restoration.3 2.3.3. assessed according to the applicable load data without exceeding specified voltage limits and equipment ratings. result in a sequential re–energization of selected loads.0 1. . 2.2 seconds shall.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL.2 and 4 seconds shall. 2.3. Deviations and variations in plant voltages from the rated equipment voltage.1 Supply Capacity The firm capacity of the electricity supply and distribution system shall be capable of supplying continuously 120% of the peak load.95. The power factor at the main station (interconnection to power utility) shall be not less than 0. Harmonic voltage–current distortion shall be as per IEEE–519 (Recommended Practices and Requirements for Harmonic Control in Electric Power Systems).4 System Power Factor The overall system power factor shall not be less than 0. A comprehensive study shall be carried out to provide appropriate methods to eliminate these events.9 lagging at rated design throughout the process unit. –20%.96 Página 9 Indice norma 2. 7 2. operating with normally open tie breakers.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . exception for secondary selective substation. The short circuit rating of low voltage switchgears shall be as stated in Engineering Design Guide PDVSA 90619. a. plant substations will be of the double–ended type. . insulation levels.7.1 2.3 2. Transformer rating shall be selected such that the starting of the largest motor will not cause the motor terminal voltage to drop below 80 percent of the normal operating level. b.2 In general.1 Electrical Protection And Control General The electrical system components shall be coordinated in regards to short circuit capability.5. protective relaying. shall be based on the parallel operation of all available supplies.010 (Application Guide for AC High–Voltage Circuit Breakers Rated on a Symmetrical Current Basis).6. Protective relay settings shall be based on a study of the fault conditions for which the protective system has been incorporated.3 2. shall be rated self cooled (OA) 65° C/Fan Cooled (FA) 65 oC. 2. Ratings of equipment are indicated in Engineering Design Guide PDVSA 90619.1. Phase and ground overcurrent protection shall be provided in all MV and LV incoming and outgoing circuits.4 2. Each transformer shall be sized such that its 65° C self cooled rating be equal to 120% of the maximum demand of the served load.053.6. For MV and LV secondary selective substation.5.2 Short Circuit Ratings All equipment shall be capable of withstanding the effects of short circuit current passing through the system in the event of circuit faults. The short circuit ratings of medium voltage (MV) equipment and cables. durability and reliability.6.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL.96 Página 10 Indice norma 2. 2. Transformers. Protective relay system shall be selective and the settings shall be coordinated such that back–up protection is provided to initiate fault clearance in the event of protective system and / or switching device failure. Short circuit calculations shall conform ANSI/IEEE C37.4 2.1. interchangeability. commissioning and start–up shall comply with all the applicable rules of ANSI/NFPA 70 and ANSI C2. such as small motors and general–purpose circuits.6 2.5. An exception to this requirement are those LV branch circuits in which phase overcurrent protection coordinates with upstream ground fault protective devices. transient stability. Electrical power supply during construction. the short circuit ratings shall be calculated with one incoming line breaker open and the bus tie breaker closed.053.6. 7. vibration protection and turbine trips.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. e. Trip circuit supervision will be applied to all high and medium voltage circuit breakers and arranged to provide an alarm on trip circuit interruption. One 86 N. temperature and humidity of cooling air. contact shall be used to repeat the tripping signal to the circuit breaker or contactor. Protective Devices Short circuit protection.O.3. c. voltage controlled overcurrent protection. If generator is connected to the system via an unit transformer. delayed ground fault protection. a. The second contact shall be wired to a lock–out relay (86). automatic voltage regulator. Short time current carrying capability shall be three (3) seconds for HV and MV switchboards. vibration. contact shall be connected in series with the closing coil (permissive). 2. synchronizing failure.96 Página 11 Indice norma c.3 a. restricted ground fault protection. a 2.7.2. b. loss of lubrication. A protection drawing shall be prepared as indicated in PDVSA N–201. underfrequency protection. b. Switchgear Protection The 115/69 – 34. bearing temperature. at both voltage levels as agreed with the owner.1.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . contacts.O. reverse power protection. one 86 N. Protective relays shall have two N. stator temperature (by embedded thermocouples). d. the generator shall be provided with high impedance grounding equipment and relevant alarms. paragraph 3. over–excitation protection.C.7. differential protection. loss of excitation protection.2 Generator Protection Protection shall be arranged to isolate generator or generator and unit transformer (if provided) from the power system. Unrestricted short circuit current and ground fault protective devices shall be applied at the remote end of the switchboard incoming circuit feeders which shall also serve as protection of switchboard bus bars in the event of bus bar faults and as back–up to switchboard outgoing circuit protection. over temperature.5 kV main substation. overvoltage protection. shall be protected by bus–zone differential protection. and alarms for protection equipment indicated in 2. Alarm equipment Rotor ground fault. Frequency relay (81) and undervoltage relay (27) shall not be wired to the lockout relay (86). negative phase sequence protection. . One contact shall be wired directly to the trip coil circuit. and one (1) second for LV switchboards. be provided with biased differential protection (87T). overpressure switches should be fitted to HV capacitor units and connected to trip the capacitor bank.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . Primary circuit ground fault protection shall be by a residual current relay. Power transformers. The transformer primary and secondary cables shall be included within the protected zone.4. Phase short–circuit protection shall be by means of two–stage overcurrent relays. set to achieve minimum fault clearance time.5 kV and above shall also be provided with differential protection. The secondary circuits of all distribution and generator unit transformers shall have separate ground fault protection by means of an overcurrent relay (51G) which shall be energized by a current transformer placed in the neutral–ground connection of the power transformer secondary winding. 49. 87T. Stage 1 being time delayed and set to detect secondary circuit faults.7.7.4 a. (fault pressure relay) and Buchholz relay (63) for conservator type transformer.7. Sealed transformers shall be provided with an automatic resetting pressure relief device. For large capacitor banks exceeding 1000 kVAr the capacitors shall be conected in double star with unbalance protection monitoring the star point voltages. shall be provided with a sudden pressure relay device. or with differential current protection across the two halves of the capacitor bank.5 . Transformer protection trips (26. f.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. 50. 63. Capacitor failure shall trip the bank and provide an alarm indication. d. The fuses shall comply with IEC 549 and shall be esily accessible for inspection and replacement. c. Capacitor Protection HV capacitor banks shall comprise individually fused capacitor units.96 Página 12 Indice norma 2. b. Transformers shall be provided with a hot oil temperature indicator and combined alarm and trip relays of approved design. Stage 2 being instantaneous (High Set elements) in operation and set to detect primary circuit faults only. All transformers 34. 51G) shall be wired to a lockout relay 86T and shall have their individual alarms. Power Transformer Protection Power transformers (Dy) shall be controlled and protected on the primary side by circuit breakers in conjunction with phase short–circuit and ground fault protective relays. Power transformers having HV or MV on the windings shall be provided with winding hot spot temperature and magnetic oil level with alarm and trip relays.1). Power transformers with 480 V on secondary winding shall be provided with extremely inverse definite minimum time relay in accordance with IEC 255–4 Type C. g. 2. rated 10 MVA and above. e. Sealed transformer of 500 kVA and above. shall further (2. h. If recommended by the Manufacturer. ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . Other methods shall be approved by the owner. circuit breakers or for LV applications by fused switch units.96 Página 13 Indice norma Individual capacitors shall be controlled by contactors. a single switching device and associated relays and/or fuses that control and protect both the motor and the capacitor shall be provided. Motors above 1. In those cases where a capacitor is connected in parallel with an electric motor.7. shall be controlled by circuit breakers with surge suppressors. MV motors shall be protected by a multi–purpose motor protection relay with all the above functions included. . Medium voltage motors shall be controlled by fused vacuum contactors of the latched mechanism type. using microcomputer technology. Asynchronous Cage Induction Motor Protection Induction motors shall be switched direct on line. They shall be rated for at least 1.1 to 5 s) or inverse time undervoltage relay for each motor. The switching devices shall be approved for this duty by the switchgear manufacturer.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. Other methods shall be approved by the owner. and must be able to withstand transient inrush currents up to 100 x In Contactor or switch controlled capacitor banks shall be protected by means of fuses. Each starter shall be provided to operate in conjunction with the undervoltage relay with and adjustable time relay (range of 0. phase fault and earth fault protection relays shall be provided. Medium voltage motors shall be protected as follows: – Undervoltage protection: One instantaneous undervoltage relay in each bus (range about 70/100% of nominal voltage). In the case of cicuit breaker control.6 a. – Instantaneous ground fault protection (suitable for resistance grounded system) – Thermal overload protection – Unbalanced loading – Bearing temperature detection – Locked rotor protection – Stator temperature detection for motors above 1 500 kW (2 000 hp) – Differential protection for motor over 1 500 kW (2 000 hp). – Short circuit protection: Motors controlled by contactors shall be protected by current limiting fuses with antisingle phasing features.5 MW (2 000 hp) at 4 000 V. 2. b. c.5 x In. Motors controlled by circuit breakers shall be protected by overcurrent relays (High Set). ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . three–wire used to supply motor loads (non critical) . Overhead Line Protection Overhead lines of primary distribution feeders shall be controlled and protected by circuit breakers in conjunction with phase shortcircuit and ground fault protective relays. The residual operating current shall be 30 mA for single – phase convenience outlets and 500 mA for 3–phase power outlets. Unless otherwise specified the overcurrent relays will be of Inverse Definite Minimum Time (IDMT) in accordance with IEC 255. three–phase. Low voltage motors (460 V) shall be protected as follows: – Short circuit protection by molded case circuit breakers (MCP type). Cable Feeder Protection MV cable feeders for distribution (not transformer feeders) shall be controlled and protected by circuit breakers in conjunction with phase overcurrent (50/51) and ground fault (50N/51N)) protective relays.8 2. – Core balance ground leakage protection for motors above 30 kW (40 hp).7. heating and fractional horsepower motor loads.5 kV duplicated underground cable feeders. 2. – Electronic Restart Module for essential motors. b.8. and for smaller motors whose phase short–circuit protection doesn’t coordinate with upstream ground fault protective devices. 120/240V single–phase.96 Página 14 Indice norma d.7.7 a. 2. three–phase. three–wire 208Y/120V. control. When distance protection is employed it shall be provided in conjunction with overcurrent and ground fault protection. four–wire 480Y.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL.4 Type A with high set elements incorporated. 2. Differential protection shall be provided on all 34. instrumentation. the latter serving as back–up protection. – Thermal overload protection with antisingle phasing protection. These systems include: a. b.1 System Grounding Solidly Grounded Neutral Systems The solidly grounded neutral shall be used for all the low–voltage systems that supply lighting. Ground faults shall be cleared by the motor circuit breakers through built–in shunt trip devices.8 a. Power and Convenience Outlets Protection Each power and convenience outlet circuit operating at low voltage shall be protected by phase short circuit protective devices and by current–operated ground leakage protective devices.9 2.7. b. c. Two units shall be installed and connected in parallel. High–Resistance Grounded Neutral Systems The high–resistance grounding shall be used on low voltage systems supplying motor services (480V) for critical continuous processes. This system provides the advantages of the ungrounded system and the main advantage of the solidly grounded system. Ungrounded Electrical Systems Ungrounded electrical systems shall not be used for new facilities.9 2.5 kV.16 kV. The UPS system shall be fully redundant. which limits transient overvoltages.8. source shall be taken from the UPS source. Low–Resistance Grounded Neutral Systems Low–resistance grounded neutral systems shall be used for all medium–voltage distribution where large rotating machinery may be directly connected to the system. This generally applies to the levels of 4.2 2. which includes two rectifiers. three–phase.8 kV and 34. 2.c system for process control and safe– guarding systems shall be 1/2 hour for normal process units and 1 hour for utility units at the maximun load. 13. four–wire system is used to supply lighting loads.1 Electric Supply Facilities for Process Control and Safeguarding Systems The battery autonomy capacity of the d.c. The electricity supply for safeguarding systems shall be taken from a dc source of supply. three–phase.2 .8. A detection and alarm system shall be provided to the trace the ground fault thoughout the system. two inverters and one battery bank.96 Página 15 Indice norma d. separate transformers should be used for this service rather than combining the service with the motor loads.9. 2.c. such as petrochemical plants and refineries. 480Y/277V. The electric supply for process control equipment shall be provided from an UPS system.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL.3 2. but in some cases 600 A or 800 A may be selected.4 2. If the safeguarding is an integral part of the process control system the requirements shall be met by the UPS system.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . The resistor is generally sized to limit the ground–fault current to a value of 400 A. The use of solidly grounded neutral systems for motor circuits and other power feeder circuits is generally limited to the 480V voltage level and should be considered when such loads are not part of critical continuous processes.9. four–wire used to supply 277V lighting loads When the 480Y/277V. The a. supply for the d. The appropriate replacement is a high–resistance grounding system.8. 1.1. The switch shall be arranged so that the selected breaker trips after all three breakers are closed.1.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA .3 3. LV switchgear shall be metal enclosed in accordance with ANSI C.1. Sections 3.96 Página 16 Indice norma 3 DESIGN AND SELECTION REQUIREMENTS EQUIPMENT.37.1 FOR Switchgear Switchgear and controlgear shall be in accordance with PDVSA N–201. Protective relaying coordination criteria for secondary selective substations is presented in a summary table in Appendix B.8). 8. Switchgear and each incoming feeder shall be designed to withstand 120 percent of maximum expected load.20. Incoming lines may thus be momentarily paralleled during switching to prevent service interruption.V and L.2 “Standard for Metal–Clad and Station–Type Cubicle Switchgear”.1 3.054 and Technical Specification for M.3.1.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. 9 and Engineering Design Guide PDVSA 90619.7 . 3. supplying essential loads. For substations serving process units which are subject to periodic shutdown (turnaround) for maintenance and repair. shall be secondary selective with automatic transfer. 4160 and lower voltage switchgears.4 3.1. MV switchgear structures shall be metal clad in accordance with ANSI C.053 – 90619.20.37.1 “Standard for Metal–Enclosed Low–Voltage Power Circuit Breaker Switchgear”.V. The trip selector will have only 3 positions: one position for bus tie breaker and one position for each incoming line breaker. MV and LV switchgear shall be provided with a synchronizing check relay (25) when required. Control and protection schematic diagrams shall be designed according to PDVSA Drawings (N–201).5 3.1.4). When two or more secondary–selective substations are interconnected in cascade.6 3. switchgear Switchgear and controlgear installations for process area shall be located indoor in a closed air conditioned building in a non–hazardous areas and near the center of the load. Section 9. Medium voltage up to 36 kV and low voltage plant substation shall be of a double ended secondary selective design. automatic transfer of downstream substation shall be time–delayed to allow for the upstream substation to complete its transfer operation. Section 3.1. CABLES AND INSTALLATIONS 3. (See PDVSA N–201. essential service required during shutdown shall be segregated from service during normal operation.2 3. The turnaround power center shall have an alternative supply from each main bus with manual transfer and interlocking against paralleling the main busses.1. The secondary selective switchgears shall be provided with a trip selector switch for manual switching (PDVSA N–201. Soft start or reduced voltage can be used with owner’s approval. LV/MV contactors and circuit breakers shall be of the withdrawable type. MV circuit breakers. MCCs and switchgear back to back type are accepted with owner’s approval. MV switchgear shall be provided with a frequency relay (81) in each bus section to shed MV non–essential motors in case of generation deficit. Contactors shall be capable of interrupting the locked rotor current of the motor (NEC 430–82) according to NEMA or category AC4 according to IEC 947–1 and 947–4–2. 3.11 3.1.1. Latched switching devices shall be provided with a healthy trip pilot lights to supervise condition of tripping circuit.1. not less than 12 gauge sheet steel (2. The load shedding system shall prevent relay misoperation due to motor residual voltage during automatic bus transfer.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . to indicate open–close operation. LV motor control center shall be combination of MCP circuit breaker and air break or vacuum contactor. LV contactors shall be air break type electro–magnetically operated.14 3. MV contactors shall be latched type.9 3. All breakers and starters shall be provided with pilot lights.1. MV breakers shall be of spring charged motor type. hold–in type.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL.96 Página 17 Indice norma 3.8 The switchgear shall be modular type sheet steel cubicles.1. non reversing. Starters shall be full voltage.1. non sticking gaskets.12 3. all critical motor starter shall be provided with the ERM relay. and MV contactors shall be of the vacuum or SF6 type. Each LV starter shall be provided with a complete wired base for connecting a plug–in Electronic Restart Module type ERM or TDRM for immediate or delayed restarting of motors after mains voltaje sag or interruption.1. Watthour.1. in order to comply with paragraph 2. LV circuit breakers shall be air break type.13 3.5 kV breakers. A running hour counter and operation counter shall be provided for each MV motor starter. voltampere and ammeter with demand interval of 15 minutes shall be provided in stations 500 kVA or larger. 3. green and red. The bus bar system for MV and LV.10 115 and 69 kV breakers shall be of SF6 type.15 3. and shall be provided with space heater controls.1.75 mm) structural steel frame work.3. combination type. All MV breakers shall be provided with mechanical operation counter. Aditionally. shall be insulated to the most practicable extent and its connection arrangement shall be fault–free. Doors shall be provided with non absorbent. floor mounting and self supporting with a degree of protection as a whole of not less than Nema 12 or IP42 (IEC 529) without using the floor as part of the enclosure. single speed. except in gas insulated switchgear application.16 .2. including 34. The vacuum and SF6 breakers shall have a chopping current less than 5 A.17 A maximum of one MV breaker or contactor shall be supplied in any vertical section.20 The vacuum and SF6 contactors shall have a chopping current less than 0.1.1.96 Página 18 Indice norma 3. One spare (equipped) motor starter shall be provided in each 4160 V bus section. Two in one column shall be approved by the Owner.19 3. The following spare 480 motor starters and spaces shall be included in every motor control center: NEMA Size 1–2 3 and larger Spare 5% 1 unit Space 5% 1 unit 3.75 A.18 3.1. Components of switchgear shall be standardized as much as possible.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA .Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL.1. At least one spare and one space cubicles should be provided in each 480 V power distribution center bus. Control power shall be as follows: MV breakers: 120 V ac for spring charged motor 125 V dc for closing 125 V dc for tripping . LV breakers: (incoming and bus tie breakers). and in general Polyclorinated Biphenyls (PCBS) are not acceptable. two 2. Liquids known under trade names like Askarel.12.2. Power transformers for Plant Stations shall be of the outdoor type.3 Transformer size shall be based on 65° C rating self cooled (OA).2.2 Transformers Power and distribution transformers shall be in accordance with PDVSA N–201. Clophen. MV latched contactors: 120 V ac for closing taken from its own voltage transformer. Oil immersed transformers shall be filled with oil manufactured locally. 3.2. Piralene.96 Página 19 Indice norma A dc supply unit (for closing and tripping).051. LV contactors: 120 V ac for closing from transformer provided separately in each starter.5 . The ability to withstand thermal and dynamic effects of short circuits shall be of 2 s (IEC 76. etc. As MV breakers mentioned above. approved by Covenin.10).2 3. approved by the owner’s engineer.8 times the transformer rated current. oil filled. Five such starts may take place in succession at 5 seconds interval. 3.5) for transformers of Plant Substation and 3 s for Main Stations and Power Plant Station.Unless otherwise specified. consisting of one rectifier unit and one battery unit.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . 125 V dc for tripping taken from the dc units. or equivalent approved by the owner’s engineer. The rectifier shall be fed by 120 V ac taken from the voltage transformer of the section concerned with change–over facilities.12.1 3. 65° C rise (ANSI C57. Main bus and feeder capacities shall be equal to the maximum fan cooled transformer rating. Section 7 and Engineering Design Guide PDVSA 90619. Provisions do not include the supply of the fans and their power supply. and shall be equal or greater than the substation maximum demand multiplied by a factor of 1.2. 3. Transformers rated 750 kVA and above shall have provisions for future addition of automatic cooling fans.4 3.5% above and two 2. shall be installed for each section of the switchgear with change–over facilities.00 and C57. Power transformers shall be capable of withstanding infrequent restarting loads of up to 1.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. with an externally operated off circuit primary tap changer with four full capacity taps. transformers shall be naturally cooled by means of integrally mounted radiators.1.5% below rated primary voltage. Pyranol.20.2. 2.5 MVA.2. the cable box shall be so constructed as to permit the coupling of the bus duct to the box without losing the minimum degree of protection. At Main Station. A grounding bolt of adequate size shall be provided for each cable shield and shall be located inside the box. Low voltage wiring shall be segregated by metal barriers.10 MV and LV boxes. tables 3. a motor mechanism and automatic control devices. For system voltage up to 34. Diverter switch contacts shall be designed to ensure long life operation. Space heaters shall be installed inside the cable–end boxes to prevent condensation.12.8 3. Radiators for transformers.2. Primary and secondary voltage metallic ducts shall be installed directly below the transformer’s cable–end boxes up to the ground level. The boxes shall be weather proof with a minimum degree of protection of IP 55 or NEMA 4.9 3. shall be provided with disconnecting links to isolate the cable from the transformer terminals for testing purposes.11 3. Diverter switch tank shall be pressure proof and provided with an overpressure (or overflow) protection device to disconnect the transformer and release the pressure completely.2. Metal sun shades shall be fitted over all boxes at approximate 50 mm above top cover. shall be fully insulated.2.7 3.12 . Each conservator shall be fitted with one oil–level indicator of direct reading prismatic glass type visible from ground level and one filling orifice with an air tight capture–screwed cap.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . Bushings shall be of an insulation class not less than that of the winding terminal to which they are connected.2.00. where specified. Transformers of the unsealed type shall be provided with a conservator tank mounted above the highest point of the oil circulating system of the equipment. It shall have an inside flexible membrane for oil/air separation. 3.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. transformers shall be provided with a three phase on load tap changer to vary the nominal voltage by plus 10% and minus 10%.96 Página 20 Indice norma 3. When the item description calls for a bus duct.on transformers above 2. 3.4 and 5. Neutral.5 kV. rated above 2 500 kVA. These ducts will give mechanical protection to power cables.6 The basic impulse insulation levels and insulation classes shall be as specified in ANSI C57. shall be detachable and shall be provided with a machined or ground flanged inlet and outlet for bolting to the transformer tank through isolating valves. for each MV winding specified with neutral brought out. The on load tap changing equipment shall consist of a liquid immersed arcing tap switch or tap selector and a diverter switch (arcing switch).2. cable terminations shall be in an integrated air–filled box suitable for mounting on the side wall of the transformer with a removable non magnetic plate and suitable provisions for terminating cable. 3. therefore. when applicable: – Purchaser order number.2.2.3 3. it shall be agreed with the owner’s engineer. considered mandatory. – Indication of provision for future forced cooling equipment – Maximum operating pressure of oil preservation system (positive and negative). shall be fully insulated. For 69 and 115 kV.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . Electric motors shall be high efficiency type.).12. .17 3.13 A durable metal nameplate of corrosion resistant materials shall be affixed to each transformer by the manufacturer.2.96 Página 21 Indice norma 3. The neutral terminal shall have an insulation class equal to the insulation class of the line terminal. Rated voltage for three–phase transformers (nominal): 115 and 69 34.2. All windings.15 Finish paint shall be light gray NFPA 70. nameplate C and the following information.12. – Tank designed for vacuum filling.16 Unless otherwise specified. the angular displacement between the primary and secondary phase voltages with a delta–wye connection shall be as per IEC 76 standard Dyn 11 (secondary voltage lags primary voltage by 30 deg. All neutral points of star windings shall be brought out to a terminal bushing.5 13.480 kV kV kV kV kV Neutral solidly grounded Grounded through low resistance Grounded through low resistance Grounded through low resistance Solidly grounded 3.1 Electric Motors Medium voltage (MV) electric motors shall be in accordance with API Standard 541 “Form Wound Squirrel–Cage Induction Motors –250 hp and larger”.16 0. The minimum information shown on the nameplate shall be that specified in ANSI C57. when the word “should” appear in the API 541 and IEEE Std 841 it must be substituted by “shall” and. 3. table 9. or IEC 76.5 kV.2. Low voltage (LV) motors shall be in accordance with IEEE Std 841 ”IEEE Standard for Petroleum and Chemical Industry –Severe Duty Totally Enclosed Fan Cooled (TEFC) Squirrel Cage Induction Motors Up to and Including 500 hp”. Unless otherwise specified herein. Alternative manufacturer’s standard is acceptable.8 4. as defined in ANSI C57.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL.14 3. up to 34.3. as long as it is at least equivalent to the above finish.00. across the line starting.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. At 80% rated voltage and rated frequency applied at the motor terminals. at 80% rated voltage and at any speed between zero and that at which pull–out occurs. Cooling system shall be air to air (CACA). Motors with aluminum frames are unacceptable. LV motors. Under these conditions. Nema II.3. All motors shall have a class F insulation.3.5 3.3. suitable for full voltage.2 MV induction motors. a Div.3. MV rotors shall be copper. once the motor is allowed to coast to rest.3. 0. all enclosure parts shall be cast iron or fabricated carbon steel sheet of 1/8 inch (3 mm) minimum thickness. Stator windings of MV motors shall be preformed and be made of rectangular copper conductors.3. 3. the accelerating torque shall be not less than 10% of the rated full load torque. with a class B temperature rise at the continuous required nameplate rating.3. Air to water cooling is not acceptable. The minimum degree of protection of an industrial motor shall be IP 54. for motors up to 7 000 hp (4 000 V). 2 motor shall be designed for temperature class T3 (200° C). squirrel cage type. which in normal service do not arc or spark or produce ignition due to hot surfaces.9 3. The starting torque characteristics shall be minimum NEMA Design B. weather–protected motors (IPW24) are not acceptable.8 3. 150 kW (200 hp up to 7000 hp) and larger. For LV motors.6 3. Motors for Division I shall be explosion proof.4). all enclosure parts shall be cast iron. For Division 2 they shall be.3 3.0. Site condition is highly corrosive. Motors shall be suitable for starting duties of at least two starts in succession after continuous running.0 service factor. (IEC 529) or TEFC–Guarded (NEMA MG–1) for the motor enclosure and IP 55 for the terminal boxes and bearing housings.3. suitable for extremes of environmental conditions and shall include antifungus tropical protection. shall be 4 000 V.12 .. Motors shall be applied within their rating based on a service factor de 1.10 3. e.3. non–sparking.56 kW to 149 shall be 460 V. For MV motors.11 3.7 3. Motors shall be ruggedized.3. in addition to (3.g pump with open discharge. In those applications requiring a prolonged overload capacity. 60 Hz.4 3. the use of a higher horsepower rating is required to avoid the reduction of insulation and bearing life associated with operation above the 1.3.96 Página 22 Indice norma 3.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . All motors shall have their windings star–connected and shall have identical insulation levels.3. it shall be adequate for starting the driven load under the most severe conditions. The kW break point may vary for reasons of economy with approval by Owner. Unless otherwise specified on the requisition. 4. Directly buried cables shall be identified with lead trips.5 kV feeder shall be directly buried. motors shall be provided with ball and roller bearing with suitable grease nipples and relief devices. Also it will affect the cable current rating unfavorably. phase segregated or phase separated type. wherever possible.480 kV shall preferably be buried directly in the ground.15 MV Motors shall be designed to be controlled by vacuum contactors.13 A terminal box of sturdy construction shall be provided with ample space for connecting the cables as indicated on the requisition order which. Motors of 75 hp and above. Motor branches 4.16 3. Motors of 1 500 kW (2 000 hp) and above shall be provided with surge suppressors. cables shall be provided with a lead sheath. Transition box between cable and motor box is not acceptable. Standardization of motors of the same size and manufacturer shall be pursued. Underground cable ducts shall be avoided in hazardous areas due to increased risks. phase insulated.4.3. about 285 kW – 3 600 rpm.2 3. 2 240 kW . Distribution feeders and branch feeders to motors shall be done. Cables shall be designed.4 3. Minimum relubrication interval to be 4 000 hours for horizontal motors and 2 000 hours for vertical motors.8 and 34.4.1.– 1 800 rpm. using armored cables. due to voltage drop. approximately 20 mm wide.1 Cables And Wires Cables and wires shall conform to PDVSA N–201.96 Página 23 Indice norma 3. large number of duct cables.5 . can be twice that considered normal by manufacturer.4. for inherent protection against fire and mechanical damage. 15 and Engineering Design Guide PDVSA 90619. by underground distribution system.3.16 and 0.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. Terminal boxes made of cast iron are not acceptable.14 3. at each end and then over their entire lenghth at 5 m intervals and at all points where they enter and leave ducts and at changes in direction. The main terminal box shall be of the non–compound filled design. Terminal boxes shall be watertight. Voltage supply shall be 120 V ac. Within the application limits.057. shall be provided with space heaters.3. 3.3. For MV motors all terminal boxes shall be made of steel. short circuit. 13.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA .3.4 3. etc. manufactured and tested according to the additional provisions of AEIC CS5 to the ICEA S–66–524 standard. and appropriate external cover to prevent electrolytic corrosion 3.17 3.4. Section 14. In areas where the possibility of soil contamination is present. 3.3 3. stainless steel. 1/0. Feeders and motor branch enclosed in duct (4. Distribution cables (13. All materials used shall be properly protected against corrosion. A technical and economic analysis shall be carried out for the selection of above ground. Cable trays and conduits shall conform PDVSA N–201.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. deviation for soil thermal resistivity.480 kV) shall be three core up to the size AWG No. Size AWG No.8 and 34.7 3. Section 14.96 Página 24 Indice norma 3. trays or cable ladders all the way up to their terminations.10 3. Shield and armor short–circuit capability shall be calculated with maximum expected phase to ground short–circuit current for a time equal to the backup protective relay setting for solidly grounded neutral systems.057. LV cables shall be PVC. PVC (75° C). The result shall be approved by Pequiven. voltage drop. or high freatic level. Cables at 600 V and below. depending on severity of environmental conditions. fire resistant polyester. Minimum size shall be as indicated in PDVSA 90619. 2/0 and above shall be one core. thermal short circuit capacity. Above ground cables are also allowed if underground cabling leads to impractical or uneconomic solutions because of excessive ground space requirements. shielded type. such as hot–dip galvanized materials.4.11 3.12 3.5 kV) shall be of one core construction.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . MV cables shall be copper cross linked polyethylene (XLPE) or ethylene propylene rubber EPR insulated (90° C) and PVC jacketed.4. Type and size of cable shall be agreed with the owner’s engineer for standardization reasons.4.9 3. and for the rated current and time of the neutral grounding resistor for low resistance grounded systems.8 3. The latter will take into account deviation for ground/ ambient temperature. and in soil with high probability of contamination where the use of cable lead sheath is not possible. and feeders to motors above 600 V.13 . shall not be increased in size because of short circuit duty.4. Cables shall be supported by cable racks. Conductor short–circuit capability shall be calculated with the maximum expected three–phase shortcircuit current circulating for a time equal to the backup protective relay setting. Calculation shall be made according to ICEA P–45–482. all agreed with the owner’s engineer.4.4. All power.6 Above ground cables are allowed in process units having equipment installed on tall structures.4. underground or a combined above ground and underground cable system.16 and 0. according to ICEA P–32–382. 3. lighting and grounding cables shall have copper conductors. reinforced fiberglass. For the sizing of cables. grouping of cables in ducts or trenches and the shield losses.1.A soil average temperature and thermal resistivity survey shall be conducted prior to perform the ampacity calculations.4. current rating and derating factors shall be taken into consideration. as protection against electrolytic corrosion.5. High pressure discharge lamps (sodium vapor type fixtures) may be used where flood lighting and street lighting be required. 3–phase. watchmen’s offices.4. Wire smaller than No.4.5.4 3. or where otherwise necessary. Ground net conductors shall be bare copper. grounding at one point may be considered with the owner’s engineer approval.17 3.5.4. Low pressure sodium discharge lamps shall not be used. 3. All lighting voltage for process plants shall be 208 V. in general. For the control of lamp groups in individual rooms of a process building.21). Section 13.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. Lighting transformers and lighting panels shall be located inside of a switch house.14 When installing shielded cable. first–aid rooms.8 3.5. Section 13. fire fighting station. For safe and effective operation. For short lengths.7 Lighting Lighting system shall conform to PDVSA N–201.2 3. Fixed emergency lighting shall be installed in control rooms. Conductors No.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA .6 3. An auto–on–off selector switch shall be located at the controller location to permit manual control of the lighting (PDVSA N–201. Instrument and telecommunication cables shall be laid in trenches or trays separated from those used for MV and/or LV cables. Lighting for outdoor operating areas and streets shall be automatic controlled by photocell.5. the main entrances and in all other buildings and areas when required for safety reasons. energy efficient fluorescent luminaries in white color shall.6 3.96 Página 25 Indice norma 3. the shielding shall be grounded at each end of the cable and at each splice.5.1 3.5. be used for plant lighting. .5.3 3. Grounding cables between equipment and ground net shall be PVC covered (green color). 12 AWG shall not be used in both lighting and power systems. Lighting levels shall be as per COVENIN 2 249 “Iluminancias en Tareas y Areas de Trabajo”.1 Power and Convenience Outlets For maintenance purposes an adequate number of 3–phase power outlets for movable equipment and single phase convenience outlets for the supply of portable tools and hand lamps shall be provided at suitable locations.5. local lighting switches shall be provided.5.5 3. For standardization reasons the same type of fittings shall be used in all plant areas. 14 AWG and larger shall be stranded.5 3. as they constitute a fire hazardous in the event of breakage. switch rooms. metallic shielding must be solidly grounded.15 3.9 3.4.16 3. 3.10 3.6. As far as practical. 3 mm2) for above ground conductors.8 3.6 mm2) for underground conductors and 6 AWG (13.96 Página 26 Indice norma 3. Switching counters and running–hour meters shall be provided on MV motor switchgear panels. enabling assessment of energy consumption for each individual processing unit. Electricity consumption metering. The following accuracy class 0. For the grounding of electrical system. Main ring conductors and branch conductors to metallic enclosures of HV/MV/LV electrical equipment shall have a minimum size of 2/0 AWG (67 mm2).7. Hand torches shall be provided for all locations where operating personnel will be present. each installation shall have one common ground grid connected to at least two groups of ground electrodes.5 3.7.3 3.8.8. 2 AWG (33.7. to prevent electrolytic corrosion of plant equipment.2 Grounding Grounding system shall conform to PDVSA N–201. (208 and/or 120 V in agreement with the owner’s engineer).5 metering instruments shall be provided per incoming circuit: active energy meter (kWh).8. voltmeter and active power meter. Excluding workshops. green PVC covered.4 3.6. 3.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . shall be incorporated. The ground grid shall extend throughout the installation in the form of main ring with insulated conductors.1 3. equipment and structures.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. Summators shall be provided to totalize kWh and kVAd for all circuits.3 3.4 . The ground grid for substation and generating station shall be bare stranded medium hard drawn copper. 3.2 Convenience outlets shall have a standard supply voltage equal to the voltage selected for normal lighting. The equipment shall consist of fixed charging units with sockets and plug–in–type hand torches suitable for classified area. Section 17.3 3.6. MV motors shall be provided with local and remote ammeter. Minimum size for branch grounding conductors to be No. apparent power maximum demand meter (kVAd). 3.1 3.7 3. each LV motor circuit of 23 kW (30 hp) and above shall be provided with an ammeter close to the motor (local).2 Metering Equipment Incoming circuits shall be provided with ammeter.7. A current transducer shall be provided at the MCC to convert the motors CT secondary current from 5 A to a 4 – 20 mA signal dc. This signal shall be connected to the ammeter close to the motor.8.7. 3.11 3.8. Section 21.9. The under floor shall be used for accommodation of incoming and outgoing cables.6.10 3.3 3. with steel doors of dust tight construction and dust tight cable passages. See PDVSA N–201. The connections between electrodes heads and conductors shall be so executed that easy inspection and testing of the ground resistance of individual electrodes be possible.8. transformers and auxiliary facilities.5. annealed copper cable with an overall PVC insulation color coded green. instruments and communications).8. Electrical switchgear installations shall be located indoor in an elevated masonery building.6 The electrical resistance between main ground grid and the general mass of earth shall not exceed 2 ohm. Pipelines and other underground metallic objects shall not be used for grounding purposes. The grounding cable shall be stranded. The single ground electrode cluster is connected to the plant ground loop. The resistance of electrodes and mass of earth shall not exceed 7 ohm.8. Trays shall be provided in this area.9. par.8. Substation building shall be air conditioned. Outdoor switchgear is acceptable with the approval of the owner (PDVSA N–201.4 3.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL.96 Página 27 Indice norma 3.7 3. This shall be accomplished by using ground busses connected to a single ground electrode cluster. For lightning and static electricity purpose. Each one shall comprise: a) One fan coil unit suitable for 100 % recirculation and free 3. The sub–station/switch houses shall be located in a safe area and designed as a completely closed civil engineering structure.2 Substations Substations buildings shall conform to PDVSA N–201. Computer and instrument system grounds shall have a simple path to ground.20. The air conditioning installation shall consist of two or more individual split system air conditioning installation.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA .9.19 and 17. to correspond to the occurrence of one air change per hour maximum.5.1 3.8 3.9 3.10).8.9. ground electrodes shall be located near the structure to be protected. Grounding of electronic system (computer.5 . Substation shall contain electrical equipment only for the safe and secure distribution of electricity such as switchgear.5 3. 17. Busses shall be isolated from the equipment ground or grid. Section 3.8. In general a separate grounding system is required and no other equipment shall be connected to it.9.9 3. A suitable drainage facility with a fire trap shall be provided. Internal temperature range to be between 29° C and 32° C.2.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. shall be extended to cover the transformer area without affecting the transformer mobility. 3.9. the substation shall be designed. constructed and protected following the recommendations listed in ANSI/IEEE standard 979 ”IEEE Guide for Substation Fire Protection”.9. by at least two panels at each end without change to the building.11 3. Transformers shall be installed outdoor in an area adjacent to the building. shall be included in the design. Provisions shall be made to avoid condensation.9. From the annunciator panel.9. major and minor common alarms shall be given to a manned control room. .6 During normal operation the maximum indoor temperature shall not rise above 35° C dry bulb.1 General A risk analysis shall be performed in the early stages of design and fully revised during the detailed engineering. Sufficient space for future extension of switchgear. Cable entry holes to the enclosure of electrical equipment shall be suitably sealed.8 3.10 3. b) One weather proof R12 or R22 hermetically sealed–type air–cooled condensing unit suitable for outdoor location. 4. In the case of breakdown or maintenance to one of the air conditioned units.9.2 4. the maximum indoor temperature shall not rise above 40° C dry bulb.7 3. The roof of the building. Each substation with HV/MV switchgear shall be provided with an annunciator panel centralizing the individual alarm and trip functions of the station equipment. The station floor shall be designed to withstand the impact stress caused by the opening of the circuit breakers under short circuit conditions. care shall be taken in the design to avoid distortion of the switchgear structure and that the equipment be completely aligned to facilitate the insertion and withdrawal of drawout equipment.9 3.9.12 4 SUBSTATION FIRE PROTECTION 4. In general. 3. Each transformer of 2 000 kVA and above shall be installed above an empty oil collecting pit with slopping bottom sized to contain the oil volume of the transformer.96 Página 28 Indice norma air delivery. For installations requiring steel channels embedded in concrete floors for switchgear support and alignment. where possible. Fire or blast walls between transformers are required for transformer of 2 000 kVA and above.1 Mandatory Requirements Removable covers for trenches shall be metal or fire retardant material.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA .9. 2.4 4.2. Transformers containing less than 8 000 liters of insulating oil shall be located not less than the following distances from building: 75 kVA or less 3m 76 kVA to 333 kVA 6m more than 333 kVA 9m Transformers can be installed close to the building if a fire–resistive wall is provided.5 m horizontally from potential fire hazards. 4. Doors shall open outward and be equipped with panic hardware and exit signs.2. Portable fire extinguishers shall be located adjacent to the doors. .2.11 Transformers shall be separated by a fire barrier having a minimum of one–hour fire–resistance rating.6 4.5 4. Oil–filled power transformers containing 8 000 liters or more of insulating oil shall be located at a minimum of 6 meters from any building.7 4.2.2.2. Smaller separation is acceptable if a fixed fire protection system is provided. The fire barrier shall extend at least 300 mm in the vertical direction and 600 mm in the horizontal direction beyond the line of sight between all points on adjacent transformers.3 4. Smoke detectors shall be installed to activate local and remote alarm. Critical wiring routed between 3 and 7.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA .5 m horizontally from potential fire hazards shall be protected by thermal insulation from fire.10 4.2. Building shall be constructed of fire–resistive non combustible materials.8 4. Critical wiring shall not be routed closer than 7.2. 4.2 Cables shall be provided with external jackets of fire–retardant material.2.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL.96 Página 29 Indice norma 4. Oil filled equipment shall not be installed inside the building. Cable openings shall be sealed to prevent the transfer of smoke and fire from one area to another.9 The building shall have a minimum of two exits located at opposite ends. 6 ECONOMICAL EVALUATION OF LOSSES The transformers and motors shall be evaluated on the basis of guaranteed total losses.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . shall be installed in non–hazardous areas. An eye–wash station shall be provided. Evaluation results shall be submitted to Pequiven for approval. 7 DOCUMENTS AND DRAWINGS All necessary drawings required for the installation and interconnection of equipment.2.14 5 POWER SUPPLY UNITS Power supply units.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. A flow switch shall be provided on each fan to give an alarm when the ventilation system is off. Transformer losses will be evaluated at the following values: US$/kW No–load loss at 100% of rated voltage Load loss at self–cooled rating Stage one cooling equipment power 3500 2900 1800 Motor losses will be evaluated at the following values: US$/kW Loss at 100% of rated voltage Cooling and lubrication equipment power 3500 1800 In the bid evaluation procedure. 4. batteries. controllers. rectifiers. Walls and floor shall be covered by an acid–resisting material.12 Battery rooms shall have a ventilation system.2. The entrance door to a battery room shall have a warning sign “PELIGRO–GAS HIDROGENO–PROHIBIDO FUMAR”. and the resulting figures will be added to the bid price to give a total evaluated price for bid comparison. each loss evaluation figure listed above shall be multiplied by its respective guaranteed loss value in kW.2.96 Página 30 Indice norma 4. such as main generator. Light switch and convenience outlets shall be located outside the battery room. cables and wires shall form part of the design. auxiliary power requirements of cooling equipment and installation cost. emergency generators.13 4. Such information shall be updated when alterations to the design are made and shall include additional information that is required during erection or may be required for future . switchgear and controlgears. ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA .96 Página 31 Indice norma maintenance. mechanical and instrumentation work. As built drawings shall be available within one month of acceptance of the construction. . trouble shooting and operation. covering all parts of the electrical installation and related civil engineering.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. Motor control Breakers and latched contactors (Trip circuits) Sodium.96 Página 32 Indice norma APPENDIX A NOMINAL VOLTAGE Main Station Power Plant Station Distribution Station Plant Station Motors above 7000 hp Motors. 3 phase 120 V ac .74 hp) & below (Non–process motors) The kilowatt break point may vary for reasons of economy with approval by the owner’s engineer.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. 150 kW (200 hp) to 7000 hp 4000 hp Motors. blended and fluorescent lighting Instrumentation Special consideration Special consideration SERVICE VOLTAGE 480 208/120 460 208/120 120 V ac single phase 125 V dc 208 V ac.56 kW (0.75 hp) to 149 kW (199 hp) Motors.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . 0. 0.55 kW (0. 50N–2 Pickup: Time: 27R–1. > Maximum expected current during normal operation. > 10 % of upstream phase overcurrent relay pickup for LV systems. 27I–2 51–1.96 Página 33 Indice norma APPENDIX B SECONDARY SELECTIVE SUBSTATIONS WITH AUTOMATIC TRANSFER SETTING AND COORDINATION OF PROTECTIVE DEVICES FUNCTION 27–1. 3s 1s Time: 51N–1. To be coordinated with relay 51 (See Arnold Kelly.(<lowest expected sustained voltage). Instantaneous. and also >Maximum expected neutral current during normal operation. To be coordinated with relay 51N–1 and 51N–2 relays. According to 51N–1 and 51N–2 relays setting (back–up).5 – 2 A). IEEE/IGA. April 1965. 27–2 Dropout: Time: Pickup: 50–1. Short Inverse.ENGINEERING SPECIFICATION PDVSA N–252 REVISION FECHA PDVSA . Instantaneous. To be coordinated with downstream ground fault relays. Inverse. 96–2 97–1. 90 % of rated voltage. To be coordinated with downstream phase OC relays. 70 a 80 % of rated voltage.8 – 1. < 25 % of rated voltage. 51N–2 Pickup: Time: 51G–1. 97–2 Pickup: Time: Time: Time: . 27R–2 27I–1. 50–2 Pickup: Time: 50N–1.Menú Principal GENERAL SPECIFICATIONS FOR ELECTRICAL ENGINEERING DESIGN Indice manual Indice volumen 0 JUL. > Both buses normal current + largest motor starting current (MV) > 125% of XFMR rated OA capacity for long time curve (LV) Aprox. 4 times XFMR rated OA capacity for short time setting (LV) Inverse. and 10 to 20 % of maximum ground fault current for MV systems.5–18 A) Instantaneous. and also >Motor contribution to a fault on the incoming circuit (12. for procedure). Inverse.5 s. Instantaneous. Time at 0 V = 0. 51G–2 96–1. < Arcing ground fault current (0. Short time: To be coordinated with downstream instantaneous relays. 51–2 Pickup: Time: Pickup: Time: Pickup: SETTING CRITERIA 70 to 80 % of rated voltage.
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