JADEER Learning Manual - Electrical Area 6 PDF

Classification: Internal Use JADEER LEARNING MANUAL ELECTRICAL AREA 6 Classification: Internal Use 0 255 4 227 77 217 247...

Classification: Internal Use JADEER LEARNING MANUAL ELECTRICAL AREA 6 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 CONTROL PAGE DISCIPLINE JOB / AREA # DESCRIPTION ASSIGNMENT Electrical Technician Area 6 Advanced Plant Electrical Maintenance Level-1 DOCUMENT REFERENCE # CONTROLS JAD-LC -A6-YP-EMT-LM MODULE # REVISION # ISSUE DATE: NEXT REVIEW DATE: 2024 2024.01 05 Nov 2024 01 Oct 2027 DEVELOPED BY: REVIEWED BY APPROVED BY: (SUBJECT MATTER EXPERTS): (SUBJECT MATTER EXPERTS): (AREA OWNERS/LEADERS): Marwan Owaidhah (12943) Electrical Ali Fallatah (12610) Electrical Specialist Bandar Al-Mesawi (13107) Electrical Trainer Specialist Ahmed Haresi (33423) Electrical Specialist Page | 2 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 YANPET SUBSTATION DESCRIPTION Page | 3 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 Table of content SN SUBJECT PAGE NUMBER 1 Introduction 6 2 34.50KV – YANPET 1 Substation Information 7 3 34.50KV – YANPET 2 Substation Information 20 4 Knowledge review 53 Page | 4 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 Objectives SN Objectives 1 To understand YANPET 34.5 Substation Construction Page | 5 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 Introduction to Electrical substation A substation is a part of an electrical generation, transmission, and distribution system. Substations transform voltage from high to low, or the reverse, or perform any of several other important functions. Between the generating station and consumer, electric power may flow through several substations at different voltage levels. A substation may include transformers to change voltage levels between high transmission voltages and lower distribution voltages, or at the interconnection of two different transmission voltages. Substations may be owned and operated by an electrical utility or may be owned by a large industrial or commercial customer. Generally, substations are unattended, relying on SCADA for remote supervision and control. The word substation comes from the days before the distribution system became a grid. As central generation stations became larger, smaller generating plants were converted to distribution stations, receiving their energy supply from a larger plant instead of using their own generators. The first substations were connected to only one power station, where the generators were housed, and were subsidiaries of that power station. Page | 6 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 Types Substations can be categorized by their various functions and roles. Step-up substation - These substations raise the voltage from generators (usually at power plants) so electricity can be transmitted efficiently. For more information on why higher voltages are more efficient for the transmission of power, see electrical transmission. Step-down substation - These facilities lower the voltage from transmission lines to what is known as a sub-transmission voltage, which is sometimes used for industrial purposes. Otherwise, the output is then directed to a distribution substation. Distribution substation - These substations further lower the sub-transmission voltage to one that can be used to supply most industrial, commercial, and residential needs, with the aid of a distribution transformer before power is finally delivered to the load. These facilities are sometimes located underground. Visit distribution grid for more information. Insulation - Switches, circuit breakers, transformers and other apparatus may be interconnected by air-insulated bare conductors strung on support structures. The air space required increases with system voltage and with the lightning surge voltage rating. For medium-voltage distribution substations, metal-enclosed switchgear may be used and no live conductors exposed to the environment at all. For higher voltages, gas-insulated switchgear, in a gas insulated substation (GIS) reduces the space required around live buses. Instead of bare conductors, buses and apparatus such as switchgear are built into pressurized tubular containers filled with sulfur hexafluoride (SF6), or an alternative gas. This gas has a higher insulating value than air, allowing the dimensions of the apparatus to be reduced. In addition to air or SF6 gas, apparatus will use other insulation materials such as transformer oil, paper, porcelain, and polymer insulators. Page | 7 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 34.50KV – YANPET 1 Substation Information 34.5KV Bus Ducts The 115/34.5KV transformers PT-6501 A/B are directly connected to the 34.5KV switchgear PS-6502 A/B by DURESCA bus ducts. (See Plates 2.6.1 and 2.5.2). The 34.5KV switchgear lineups PS-6502A and PS-6502B are also connected together with DURESCA bus ducts. This bus duct is unusual and deserves the extra space allocated in this section for a better understanding of its nature. The conductor is made up of a cylindrical tube or of a rod in aluminum alloy Ac 041. The insulation is wound directly on the conductor. It consists of wrapped paper dried in vacuum and impregnated with epoxy resin. The ground layer is embedded in the insulation material and screens electrically the environment of the bars completely from one end of the layer to the other. For the bars to transformers, over the surface of the insulation, on the straight parts of the bars, protection tubes in aluminum alloy Ac 100 shield the active insulation against mechanical injuries. This tube serves also as a protection against electrical contact. Over the bent parts of the bars, there is no metallic protection tube. Outdoor bent parts are protected and sealed with a glass-fiber-epoxy wrap. At both insulating ends is the capacitively controlled terminal part (tracking distance), where conductive condenser layers ensure a uniform axial repartition of the electrical field. The capacitively controlled end parts in the outdoor part are coated with a silicon paint to avoid formation of dew. The end parts of the bars by the transformers are equipped with waved epoxy-overcasting in order to increase the creeping distance. At the one end of the bar, in the vicinity of the protective tube, but electrically separated from it, is the ground bandage. The latter is galvanically connected with the ground layer. The insulating cylinders are mounted over the connections between the bars and insulate them. The capacitively controlled insulating cylinders are constructed in the same way as the bars. Page | 8 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 The high voltage electrode is made of one metallic tube. Directly upon lies the DURESCA insulation. The ground layer is embedded in the insulation material and shields the environment of the insulating cylinder over its full length. Over the insulation, a metallic protection tube shields the active insulation against mechanical injuries. The ground layer is galvanically connected with the protection tube. The length of the bars varies according to the dilatation due to heat. This variation has to be taken into account for the clamping. The bar is rigidly fixed at one to two points and gliding at the other points, so that it can move axially in the clamps. The number of fixing clamps of each bar is given by the short circuit stresses, the distance between them is determined in order to obtain a free length (distance between supports) not equivalent to that caused by an oscillation frequency of 100 Hz. For these reasons it is important to put the bars and to mount them as per the assembly drawing. The high current connections have to be assembled in such a way to avoid production of excessive heat and to avoid corrosion. It is important that the contact surfaces are clean and that sufficient contact pressure is continuously ensured. The insulating cylinders are slipped over the high current connections. The high voltage electrode of the cylinder which consists of a metallic tube must be connected by a spring with the conductor of the bar. The outer metallic protection tube or the ground bandage must be grounded. The capacitive grounding (or grounding of the ground layer) has to be done once on each single bar. If the ground layer of a bar is not grounded, it is acting only as indefinite potential layer. A voltage would appear between ground layer and protection tube or fastening and cause the formation of a tracking-path between both, that afterwards could lead to a break-down of the complete insulation. The protection tube has to be grounded to fulfill its function as a protection against accidental contacts. This grounding becomes only effective in case of a failure of the main insulation. No dangerous voltage can rise on the protective tube. Each separate tube must be grounded only once in order to avoid inductive currents. Page | 9 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 Inductive currents appear as follows: Conductors carrying alternative current are surrounded with alternating magnetic fields. If conducting loops exist in the neighborhood of these conductors the alternating magnetic fields pass through the loops and induced current flow. When a protection tube is grounded twice, it forms a loop which under circumstances warms up and leads to damage for the insulation. The ground layer of each cylinder has to be grounded. The other metallic parts (fixing clamps, supports, etc.) must be grounded. Loops must not be formed. The grounding of the bus ducts is critically important and must not be changed or modified in any way from that shown on MOSER-GLASER installation drawings. During construction a ground fault occurred on these bus ducts which was attributed to the incorrect ground which had not been installed in accordance with the MOSER-GLASER drawings. The bus ducts must be maintained in strict accordance with the manufacturers instructions. It will be necessary about once a year, according to the amount and kind of dust, for the capacitively controlled terminal parts of the bus ducts to be cleaned. After some years of operation it will, be necessary for insulating cylinders to be dismounted and the condition of the bars checked. The tracking distance of the bus bar and cylinder should be cleaned. The bus ducts should not be touched when they are energized. 34.5KV Switchgear PS-6502 A/B 34.5KV Switchgear Equipment The 34.5KV switchgear PS-6502 A/B is of SIEMENS manufacture, metal enclosed, indoor, fully compartmented, cubicle type, air insulated bus bar chamber, with withdrawable vacuum circuit breakers. The 34.5KV switchgear PS-6502 A/B is arranged in two separated switchgear PS-6502A and PS-6502B. These two switchgears form a parallel line-up at the far end of the main substation, as can be seen from Plate 2.7.1.1 and are coupled together with DURESCA bus ducts. (See Section 2.6). The 34.5KV switchgear instrument circuit breaker is local between the two sections of the switchgear at one end forming a V arrangement. (See Plates 2.7.1.1 and 2.7.1.2). Page | 10 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 Each incoming service, outgoing service and bus tie is provided with a withdrawable circuit breaker mounted on a truck. With the truck in the service position the conductors of the circuit breaker are connected to the bus bars as well as to the outgoing cables, incoming or outgoing bus ducts via the contact arms and the run-in contacts of the truck and the fixed mounted isolating contacts in the cubicle. The truck is locked against withdrawing. The low voltage part of the truck is connected by the low voltage plug connection. With the truck in the test position the conductors of the circuit breaker are separated from the fixed high voltage contacts in the cubicle, providing an isolating distance as allowed by the standards to which the switchgear was manufactured. The truck is locked against being moved. The low voltage part of the truck is connected by the low voltage plug connection. The circuit breaker can be switched for testing and all functions can be checked. The switchgear is provided with a truck which includes a fully rated fault making switch which is for grounding any de-energized circuit breaker circuit. This truck is also provided with three bushings, inside a separate chamber, which allows application of voltage test probe, megger and high voltage cable insulation test equipment (max 100KV for 15 min). The circuit breaker trucks are moved from the locked service or test positions by use of a special lever. This lever must be inserted in a socket in the truck locking shaft but this insertion of the lever can be prevented by fitting a padlock hasp through the hole in the shaft, allowing the truck to be locked in any position. The circuit breaker lever and all keys must be kept in a safe place and only be accessible to authorized personnel. The circuit breaker truck can also be totally withdrawn to allow complete personnel safety for cable and equipment maintenance. In the test position, the interior of the truck compartment is totally inaccessible. In the fully withdrawn position the interior of the truck compartment is accessible but all high voltage parts are inaccessible provided partitions and shutters are not deliberately removed. It is not recommended, however, that personnel should enter the truck compartment unless the switchgear is de-energized and grounded in accordance with safety procedures. The equipment is provided with one plain cubicle front, which should be used to close off access when a truck is withdrawn. Page | 11 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 The switchgear (See Fig. 2.7.1.1) consists of the following: PS-6502A 1- Incoming, circuit breaker circuit breaker, HI from PT--6501A 1- Metering, fused circuit breaker, H2 voltage transformer 1- Bus tie, circuit breaker, circuit breaker, H3 to PS-6502B 9- Outgoing, circuit breaker circuit breakers, H4 to H12 as follows: Circuit Breaker H4 - PT-3001A Circuit Breaker H5 - PT-3001C Circuit Breaker H6 - PT-3002B Circuit Breaker H7 - PT-7401A Circuit Breaker H8 - PT-6001A Circuit Breaker H9 - PT-6502A Circuit Breaker H10 - PT-6503A Circuit Breaker H11 - PT-6401A Circuit Breaker H12 - PT-2001A And 1- Outgoing, circuit breaker Circuit Breaker H13 spare. PS-6502B - 1 - Incoming circuit breaker circuit breaker, H14 from PT-6501B 1 - Metering, fused circuit breaker, H15 voltage transformer 1 - Bus tie, isolation circuit breaker, H16 to PS-6502A 10 - Outgoing, circuit breaker circuit breakers, H17 to H26 as follows: Page | 12 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 Circuit Breaker H17 - PT-3002A Circuit Breaker H18 - PT-3002C Circuit Breaker H19 - PT-3001B Circuit Breaker H20 - PT-7401B Circuit Breaker H21 - PT-6001B Circuit Breaker H22 - PT-6502B Circuit Breaker H23 - PT-6503B Circuit Breaker H24 - PT-6401B Circuit Breaker H25 - PT-2001B Circuit Breaker H26 - PT-6504 Page | 13 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 The 34.5KV switchgear has the following ratings: Busbar Data: Item Description Rating Thermal withstand (3 sec. symm) 1500 MVA Peak withstand (rated nominal current) 88 KA Continuous rating at 50 Deg. C 2000 A (24 hr. average) Circuit breaker data ANSI C37.4 1964 Rated short-circuit current 23 kA (at 38 kV) = 1500 MVA (symm.) Rated short-circuit latching 60 kA (at 38 kV) peak 2500 (1250) A at 40*C, 24 hr. aver. Rated continuous current 2000 A at 50*C, 24 hr. average (Both values relate to installation in 8BD1 cubicles) Rated short time current 25.1 kA (3 sec.) at 34.5 kV The incoming circuit breakers are provided with cooling fans mounted above the cubicles and it is essential that the supply to these fans and the fans themselves are available for operation at all times. The closing and tripping power is provided by an auxiliary 125V DC rectifier battery unit. Breakers are closed and tripped by the energy stared in springs. The springs are charged by electric motors (one per-breaker). Power for these motors, and the associated control system, is derived from Auxiliary supply.' Page | 14 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 For closing power to be available at any breaker: a) One bus must be live and/or the associated, battery must be fully charged. b) Appropriate MCB on DC circuit breaker must be closed. c) MCB -F101 and -F102 in breaker cubicle L.V. compartment must be closed. The motor will charge the closing spring immediately these conditions are fulfilled and the breaker umbilical connection between cubicle and truck is plugged in. When the springs are charged the breaker is held ready for closing. Closing the breaker automatically charges the tripping springs. The breakers fitted have a drive mechanism which stores sufficient energy for a close-open cycle in one spring charge. If closing power is not available the springs can be charged manually but breakers cannot be closed unless Auxiliary supply is available. (The trucks are NOT equipped with a direct acting manual release button.) Tripping power is derived from the same source as closing power. For tripping power to be available at any breaker: a) One bus must be live and/or the associated, battery must be fully charged. b) Appropriate MCB on DC circuit breaker must be closed. c) MCB. -FlO1 in breaker cubicle L.V. compartment closed. Circuit breakers can be deliberately tripped: automatically by protective relays OR a) IN EVENT OF TRIPPING SUPPLY FAILURE, by manual direct acting mechanical trip button on front of CB truck (red). Tripping by this button will cause the "tripped-on-fault" lamp to come on (yellow). Page | 15 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 HEATER POWER (ANTI-CONDENSATION) Derived from Power Supply. Each cubicle is fitted with one heater, 200 W. For heater power to be available: a) Appropriate Power Supply must be energized and appropriate MCB closed. b) Thermostat -B151 in C.B. L.V. compartment must be closed. Page | 16 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 PLATE 2.7.1.4 34.5kV CUBICLE CROSS-SECTION INCOMER Page | 17 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 PLATE 2.7.1.5 34.5kV CUBICLE CROSS-SECTION BUS TIE BREAKER Page | 18 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 PLATE 2.7.1.8 34.5kV CUBICLE CROSS-SECTION OUTGOER Page | 19 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 PLATE 2.7.1.9 SECTION THROUGH VACCUM CIRCUIT BREAKER Page | 20 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 34.5KV Switchgear Protection The 34.5KV switchgear is provided with two levels of protection. The first level of protection, commonly called primary protection, is very fast in operation and only responds to faults within a particular zone. The second level of protection, commonly called secondary protection, is slower in operation and responds in a coordinated sequence for faults down stream from the protection device and provides back-up protection to the primary protection. The primary protection consists of bus zone protection for all bus bars and devices. From Fig. 2.7.2.1 it will be noticed that for any fault within a zone both circuit breakers that could feed power into the fault are tripped. The zone numbers used in Fig. 2.7.2.1 are peculiar to this operating manual only. The secondary protection, shown in Fig. 2.7.2.2, consists of inverse definite minimum time overcurrent and ground fault protection. As the primary protection only responds to faults within the protected zone, protection coordination is not involved. The secondary protection overcurrent relays are set to coordinate with upstream and downstream protection devices such that in the event of a fault the nearest upstream protection device will operate first, to clear the fault from the power system, and thereby retain the maximum amount of equipment in service. Complete details of relay: types, characteristics and settings are given in the Relay Coordination and Catalogs, Book-3 of the Power System Study. It is critical for reliable operation that relays and relay settings and characteristics are checked on a regular basis. Page | 21 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 SEE ONE LINE DRAWING 65-EP-104 MAIN SUBSTATION PSU-6501 PT-6501A PT-6501B R R 87B 87B TRIP TRIP ZONE 1 ZONE 2 PS-6502A 34.5 kV SWGR PS-6502B NO TYPICAL FEEDERS TYPICAL FEEDERS 87B BUS ZONE PROTECTION FIGURE 2.7.2.1 34.5KV SWITCHGEAR PRIMARY Page | 22 SIMPLIFIED PROTECTION ONE LINE Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 34.5KV SWITCHGEAR OPERATION The 34.5KV switchgear PS-6502 A/B is provided with an automatic secondary selective transfer system. For operation and a general description of automatic secondary selective systems see the section 2.16 secondary selective systems hereof. THE AUTOMATIC SECONDARY SELECTIVE TRANSFER SYSTEM AT THE 34.5KV SWITCHGEAR PS-6502 A/B IS A SPECIAL CASE AND SHOULD UNDER NORMAL OPERATING CIRCUMSTANCES BE LOCKED OUT TO RENDER THE SYSTEM INOPERATIVE. Under certain circumstance which are discussed later the secondary selective transfer system may be enabled. Whenever a transformer is switched onto the electrical system there is a high inrush current which lasts for some time. The time of inrush current decay is a function of the electrical system time constant at that time and its initial magnitude is a function of the point in the voltage wave at the instant of switching. Also, any other transformer which is already connected to the system before a new transformer is switched onto the system may also exhibit sympathetic inrush as if it was itself being switched onto the system. The magnitude and decay time of this sympathetic inrush current is a function of electrical system characteristics at the time of switching. As can be understood from the above the total transformer inrush current on the distribution system is a variable of unknown magnitude and time duration. Calculations have been made for a worst case condition, when the total transformer inrush current is at a maximum, from which it is known that should this worst case condition occur on an auto transfer at the 34.5KV switchgear then total electrical power would be lost through low voltage and overcurrent. The probability of this worst case condition occurring is very remote but under normal operating conditions the risk is not justified. Page | 23 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 Under normal operating conditions and on the loss of one incoming 115KV supply or one 115/34.5KV transformer, - power will be available to all sections of the complex through the operation of the auto transfers schemes at the 4.16KV switchgear. After such an event the feeder breakers (on the 34.5KV switchgear) should be opened and manually closed, and individual 34.5/4.16KV transformers energized and manual transfers back to normal performed at the 4.16KV switchgear. This re-establishment of the system, apart from the lost 115KV supply or 115/34.5KV.transformer which may still not be available, should be accomplished as soon as reasonably possible after the loss of supply to one section of the 34.5KV switchgear. This will ensure that the maximum of equipment is back in service and thereby increase the reliability of the system. This will naturally not apply if the loss of the 34.5KV power supply on one section of the 34.5KV switchgear is through a fault on that section. THE AUTOMATIC SECONDARY SELECTIVE TRANSFER SYSTEM AT THE 34.5KV SWITCHGEAR PS-6502 A/B SHOULD ONLY BE ENABLED WHEN ONLY ONE 4.16KV SUPPLY IS AVAILABLE TO ANY CRITICAL 4.16KV SWITCHGEAR. As-mentioned above there is the possibility that an auto transfer at the 34.5KV switchgear, if the worst case condition was to occur, could shut down the whole power system. Also, if a critical 4.16KV switchgear for some reason has been supplied from one transformer, then the lost of this transformer would cause the loss-of the unit supplied from this switchgear and hence the whole complex. Under the condition of a critical unit being supplied by a single transformer then the 34.5KV auto transfer system should be enabled as the risk is now justified because the loss of the transformer would shut the complex down in any case. Page | 24 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 SEE ONE LINE DRAWING 65-EP-104 MAIN SUBSTATION PSU-6501 PT-6501A PT-6501B 27X 27X 27-1 27-2 -1 -2 51 50 51 50 R R 86 86 BLOCKS BLOCKS TRANSFER TRANSFER AT 34.5 kV SWGR PS-6502A 24 PS-6502B NO TYPICAL FEEDERS TYPICAL FEEDERS 51 OVERCURRENT PROTECTION 51G GROUND FAULT OVERCURRENT PROTECTION 27 UNDERVOLTAGE RELAY AT AUTO TRANSFER CIRCUITRY FIGURE 2.7.3.1 34.5KV AUTOTRANSFER SIMPLIFIED ONE LINE DIAGRAM Page | 25 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 34.50KV – YANPET 2 Substation Information 34.5kV switchgear 34.5kV Switchgear Equipment # 2PS-6503 The 34.5kV switchgear 2PS-6503 is manufactured by Merlin Gerin, metal enclosed, indoor, fully compartmented, cubicle type, air insulated bus chamber, with drawout SF6 gas filled circuit breakers. Each incoming service, outgoing service, and bus tie is provided with a drawout circuit breaker mounted on a truck. Each circuit breaker has two positions in the housing, test/disengage and engaged (service) position. The circuit breaker truck is moved from the test position or engaged (service) position by the use the locking lever. This lever is integral with the truck. With the locking lever in position “3”, the circuit breaker can be inserted in to the panel until it comes up against the stop. Connect the low voltage plug connection. Move the lever to position “1” to block the circuit breaker in position. The circuit breaker is now in the disengage or test position and it is possible to proceed with no-load operation tests. To move from the test position to engaged position, move the locking lever to position “2”, pressing the “O” button at the same time and push the circuit breaker right in. Move the lever to position “1” to block it in the engaged position. With the truck in the disengaged/test position, the circuit breaker stabs are separated from the fixed high voltage contacts in the cubicle, providing an isolating distance as allowed by the switchgear manufacture. When the locking lever is in position “1”, the truck is blocked against being inserted into the cubicle. The low voltage part of the truck is connected by the low voltage connection socket. The circuit breaker can be switched for functional testing. Page | 26 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 When the truck in the engaged position (service), the circuit breaker stabs are connected to the main bus as well as the outgoing cables. The truck is locked against removal while in the closed position. The low voltage part of the truck is connected by the low voltage connection socket. The circuit breaker truck can be totally withdrawn from the cubicle to allow complete personnel safety for cable and equipment maintenance. Each circuit breaker panel is provided with an earthing switch to earth (ground) the cable heads, enabling work to be carried out on the panel in complete safety. The earthing switch can only be closed if the circuit breaker is in the disengaged position or out of the panel. It is recommended by the manufacturer that any circuit breaker be disconnected and stored in the disengaged/test position whenever it is to be left in the open position with no planned switching. The switchgear is provided with one plain cubicle front, which should be used to close off access to cubicles, when the circuit breaker truck is withdrawn from the panel. In the test position the interior of the removable element compartment is totally inaccessible. In the fully withdrawn position the interior of the truck compartment is accessible but all high voltage parts are inaccessible provided partitions and shutters are not deliberately removed. It is recommended however that personnel should not enter the truck compartment unless the switchgear is de-energized and grounded in accordance with safety procedures. The switchgear is provided with a ground/test device truck, which includes a fully rated fault-making switch, which is for grounding any de- energized circuit breakers and to test cables. This truck is provided with three bushings, which allow application of voltage test probe, meggar, and high voltage insulation test equipment for testing cables. The 34.5kv switchgear 2PS-6503 (see figure 2.7.1.1) consists of the following: Three (3) - Circuit breakers (2 Mains, 1 Tie) rated at 2500 amperes continuous and 40KA rated short time withstand current. Twenty One (21) - Circuit breakers (Feeders) rated 1250 amperes continuous and 40KA rated short time withstand current. Page | 27 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 The individual components for each cubicle feeder are as follows: Main incoming breakers 52-1 & 52-2 Sepam 2000 T06 relay Sepam 2000 D02 relay PQM, power metering unit. Tie breaker 52-24 Two (2) Sepam 1000 S01 relay Two (2) Sepam 100LD relay Sepam 2000 R01 relay Basler BE1-25 Feeder breakers Sepam 2000 T01 relay PQM, power metering unit. Page | 28 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 The 34.5kV switchgear has the following ratings: Main Bus Data: Maximum operating voltage 36kV Thermal withstand 2500MVA Peak withstand current 100KA Continuous current 2500A Impulse withstand voltage 170kV Circuit Breaker Data: Rated short circuit current 40KA at 36kV Rated short circuit current latching 100KA at 36kV Rated continuous current 2500A at 40oC Main & Tie 1250A at 40oC Feeder brkr Impulse withstand voltage 170kV Insulation withstand voltage 70kV Page | 29 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 Picture 2.7.1.1 34.5kV Switchgear Page | 30 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 TRANSFORMER RATINGS SEE ONE LINE DRAWING 265-DP-014 SHT 2 FOR 28 SPACE 26 TO 2PET-6504; 2PSU-6501B FIG 2.3.2.1 ESSENTIALS BUS MAIN SUB 22 SPARE 20 TO 2PT-6511B; 2PSU-6501B MAIN SUB FIG 2.3.3.1 18 TO 2PSW-6503B; 2PSU-6503 FIG 2.3.5.1 EAST OFFSITES 16 TO PSW-6502B; 2PSU-6502 2PS-6503B FIG 2.3.4.1 WEST OFFSITES SPARE 14 115 kV SWGR 2PS-6501B 6 TO 2PSW-4101B; 2PSU-4101 FIG 2.3.10.1 2PT-6503B POLYPROPYLENE REACTION UNIT 12 TO 2PSW-3001B; 2PSU-3001 FIG 2.3.9.1 POLYETHYLENE REACTION UNIT 10 TO 2PT-3601B; 2PSU-3601 FIG 2.3.8.1 POLYMER FINISHING UNIT 2 4 FROM ROYAL COMMISSION 8 TO 2PSW-3601B; 2PSU-3601 FIG 2.3.8.2 MYAS POWER PLANT POLYMER FINISHING UNIT 2 6 TO 2PSW-2001B; 2PSU-2001 FIG 2.3.7.1 R ETHY-GLYCOL UNIT 4 TO 2PSW-1001B; 2PSU-1001 FIG 2.3.6.1 ETHYLENE UNIT NC NC 24 24 2PT-6503A 3 TO 2PSW-1001A; 2PSU-1001 FIG 2.3.6.1 ETHYLENE UNIT 34.5KV 1 5 TO 2PSW-2001A; 2PSU-2001 FIG 2.3.7.1 ETHY-GLYCOL UNIT 7 TO 2PSW-3601A; 2PSU-3601 FIG 2.3.8.2 3 1 POLYMER FINISHING UNIT 9 TO 2PT-3601A; 2PSU-3601 FIG 2.3.8.1 POLYMER FINISHING UNIT 11 R 2PS-6501A TO 2PSW-3001A; 2PSU-3001 FIG 2.3.9.1 2PS-6503A POLYETHYLENE REACTION UNIT SPARE 13 5 TO 2PSW-4101A; 2PSU-4101 FIG 2.3.10.1 POLYPROPYLENE REACTION UNIT 15 TO PSW-6502A; 2PSU-6502 115KV SWGR BLDG FIG 2.3.4.1 WEST OFFSITES 2PSU-6501A 17 34.5KV SWGR BLDG TO 2PSW-6503A; 2PSU-6503 FIG 2.3.5.1 EAST OFFSITES 2PSU-6501B 19 TO 2PT-6511A; 2PSU-6501B MAIN SUB FIG 2.3.3.1 21 SPARE 23 SPACE Figure 2.7.1.1 34.5kv Switchgear Simplified One Line Diagram Page | 31 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 2.7.2 34.5kV Switchgear Protection The 34.5kV switchgear 2PS-6503 is provided with two levels of protection. The first level of protection commonly called primary protection is very fast in operation and only responds to faults, which occur within a particular zone. The second level of protection commonly called secondary protection, is slower in operation and responds in a coordinated sequence for faults occurring down stream from the protection device and provides back-up protection to the primary protection. The 34.5kV switchgear is operated with the tie breaker normally closed. With the tie breaker normally closed, a fault on either Bus A or B will result in fault current flowing through both incoming main breakers for as long as the tie breaker is closed. The SEPAM relays used in the 34.5kV switchgear are highly accurate, fast acting, electronic relays. The protective relaying philosophy for the 34.5kV switchgear consists of instantaneous fault sensing as the primary protection with a backup time over current fault sensing and circuit breaker trip. Downstream fault conditions will be cleared by their respective feeder breaker. In the event that the relay for the feeder breaker fails to trip, the relay failure protection scheme will provide a trip signal to any failed down stream protective relays 100 milliseconds after the first breaker protective relay trip signal has been given. Fault conditions not cleared by a feeder breaker will then be cleared by isolation of the 34.5kV bus where the fault condition exists. The first step in fault clearing will be to open the 34.5kV bus tie (breaker 2PS-6503-52-24). If the fault condition remains 100 milliseconds after the breaker fail signal to all downstream breakers has been given, then the relay failure protection scheme trips the tie breaker approximately 150 milliseconds after the feeder breaker fault clearing time. This action will separate the two 34.5kV buses and isolate the fault to only one bus. The main breaker sensing the fault condition will clear the fault. The main breaker clearing operation will occur 250 milliseconds after the tie breaker has been tripped. Page | 32 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 Incoming 34.5KV Power from 115KV Breakers (52-1, 52-2 & 52-24) Primary protection for 34.5KV incoming power from 115kV system is provided by SEPAM 2000-D02 and SEPAM 2000-T06 relays. These relays act to trip the 115KV transformer feeder breaker and the main incoming 34.5KV breaker when a fault occurs. The SEPAM 2000-D02 relay provides transformer phase and ground differential (87T and 87G) protection of the 115KV/34.5KV transformer 2PT-6503, 115KV feeder cable, and 34.5KV bus duct. The SEPAM 2000-T06 relay provides directional time overcurrent protection (67 and 67N) to detect 115KV system fault during operation with the 34.5KV tie breaker closed. Additional transformer and feeder protection is provided by SEPAM 2000-T63 which include instantaneous and time overcurrent (50/51 and 50N/51N) protection. This SEPAM is located in the 115KV switchgear. Main Bus Protection The 34.5KV protection scheme for the main power bus is split into two zones, corresponding to A & B buses. In the event that a single 34.5KV breaker is unable to isolate a fault, all 34.5KV breakers connected to that zone/bus will be tripped. This protection scheme is provided by SEPAM 100LD, SEPAM 1000-S01, and SEPAM 2000-T06, to provide complete redundancy for all portions of the 34.5KV power system. The SEPAM 100LD relays provide differential protection (87B) for the 34.5KV bus, and will trip all breakers connected to that bus, in the event of a bus fault. The SEPAM 1000-S01 relay provide overcurrent protection (51 and 51N) in a partial bus differential scheme for the 34.5KV bus. In the event of a bus overcurrent condition the relay will trip the associated incoming main and tie breakers. Page | 33 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 The SEPAM 2000-T06 relay provide the following protections: Instantaneous and time overcurrent functions (50 and 50N) to provide direct tripping of the main incoming breakers in the event that a downstream device dose not clear a fault. Backup instantaneous functions (50BU and 50BU) to provide backup tripping to the 34.5KV feeder breakers connected to the respective bus in the event of a feeder breaker relay failure. Ground fault protection (51G-1 and 51G-2) which provide backup protection for feeder relay failure and main bus ground fault protection. Permissive closing of the 34.5KV main and tie breakers is provided by the Basler relay (25), which verifies the synchronization of the incoming supplies. Feeder Breakers (52-3 through 52-28) The protection for the 34.5KV feeder breakers is provided by SEPAM 2000-T01 relay which provide instantaneous and time overcurrenct protections (50, 51, 50G and 51G) for feeder cables to the power utilization transformers at the units PSUs. Figures 2.7.2.1 and 2.7.2.2 show the 34.5kV primary and secondary protection respectively. The zone numbers used in both figures are unique to this operating manual. Complete details of relay operation, types, characteristics and settings are provided in the Relay Coordination Study number, CS-P-265004. It is critical for reliable operation that the relays, settings and characteristics are checked on a regular basis. For more power metering accuracy, each 34.5kV feeder breaker is equipped with a GE Multilin PQM unit. Refer to drawing # 265-DP-025 sh.001 to sh.005. Page | 34 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 SEE ONE LINE DRAWING 265-DP-025 MAIN SUBSTATION 2PSU-6503 2PT-6503A 2PT-6503B 87B 87B ZONE 1 1 TRIP TRIP 2 ZONE 2 24 34.5 kV SWGR 2PS-6503A 2PS-6503B NC TYPICAL FEEDERS TYPICAL FEEDERS 87B BUS ZONE PROTECTION Figure 2.7.2.1 34.5kv Switchgear Primary Protection One Line Diagram Page | 35 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 SEE ONE LINE DRAWING 265-DP-025 MAIN SUBSTATION 2PSU-6503 2PT-6503A 2PT-6503B 51 51N 51N 51 51G 51G 51G 51G 2 2 R R 50 67 67 50 67 50 50 67 N N N N 1 TRIP TRIP 2 TRIP ZONE 2 24 34.5 kV SWGR 2PS-6503B 2PS-6503A NC 50 51 50 51 TYPICAL FEEDERS TYPICAL FEEDERS 67 DIRECTIONAL OVERCURRENT PROTECTION 51 OVERCURRENT PROTECTION 51G GROUND FAULT OVERCURRENT PROTECTION Figure 2.7.2.2 34.5kv Switchgear Secondary Protection One Line Diagram Page | 36 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 34.5kV Switchgear Operation The closing and tripping power is provided by 125V DC rectifier/battery unit. Breakers are closed and tripped by the stored energy springs. These springs are charged by electric motors. Power for these motors and the control system is derived from the 125V DC supply. For closing power to be available at any breaker: a) One bus must be live and/or the associated battery must be fully charged. b) Appropriate breakers on the DC panel must be closed. c) Switch Q5 and Q6 in breaker cubicle low voltage compartment must be closed. The motor will charge the closing spring immediately whenever these conditions are satisfied and the low voltage connection socket between the cubicle and truck is plugged in. When the springs are charged, the breaker is held ready for closing. Closing the breaker automatically charges the tripping springs. The breakers have a drive mechanism which stores sufficient energy for a close-trip cycle in one spring charge. If closing power is not available, the springs can be manually charged, however, the breakers cannot be closed unless the control power supply is available. Tripping power is derived from the same 125V DC power source as closing power; however, tripping power is supplied from a separate circuit breaker in the DC panel. For tripping power to be available at any breaker: a) One bus must be live and/or the associated battery must be fully charged. b) Appropriate breaker on 125V DC panel must be closed. c) Switches Q3 and Q4 in breaker cubicle low voltage compartment must be closed. Page | 37 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 Circuit breakers can be tripped: a) Automatically by protective relays b) Manually by control switches at operators console c) IN THE EVENT OF TRIPPING POWER FAILURE, by manual direct acting mechanical trip button on the front of the truck. Each cubicle is equipped with an anti-condensation space heater powered from normal 120V AC source. For heater power to be available: a) Appropriate 120V AC power supply must be energized. b) Switch Q7 in breaker cubicle low voltage compartment must be closed. c) Thermostat B in breaker low voltage compartment must be closed. Page | 38 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 34.5kV SF6 Disconnect Switches The 34.5kV Load break disconnect switches are manufactured by Powell ESCO. Each switch is metal enclosed, outdoor, air insulated bus chamber, fixed position and SF6 gas filled (see picture 2.7.4.1) The 34.5kV disconnect switches are arranged in a single outdoor line up without an incoming load break switch. Each outgoing service is provided with a fixed SF6 gas filled switch (See figure 2.7.4.1) and a pressure switch with alarm set at 5 PSIG (34.5 kPa). At no time should the fill pressure exceed 13 PSIG (90kPa). Each disconnect switch has three positions, ground, open, and closed. The operating mechanism moves from GND-open-closed to close the switch and closed-open-GND to open the switch. The switch is provided with an anti-pass through device to prevent incorrect operation. The 34.5kV Disconnect Switch has the following ratings: Maximum operating voltage 38kV Impulse withstand voltage 125kV Continuous current 600A Load Break current 600A Rated short circuit current 40KA at 38kV Rated short circuit current latching 40KA at 38kV Page | 39 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 Picture 2.7.4.1 35 kV SF6 Switches Page | 40 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 SEE ONE LINE DRAWING 265-DP-014 SHT 1 1 34.5KV 24 SWITCHGEAR 2PS-6503 NC 2PSW- 34.5KV SF6 SWITCH 40KA ASYMMETRICAL 2PSW-3 2PSW-2 2PSW-1 600A 600A 600A SPARE TYPICAL FEEDERS TYPICAL FEEDERS POW ELL-ESCO CLASS 820 LOADBREAK GAS SW ITCH 600A CONTINUOUS, 40KA ASYMMETRICAL MAKE & LATCH Figure 2.7.4.1 34.5kv Disconnect Switches Simplified One Line Diagram Page | 41 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 Medium Voltage Transformers Medium Voltage Transformer Equipment The 34.5/13.8kV and 34.5/4.16kV transformers are of ABB manufacture. The transformers are connected to the 34.5 kV switchgear PS-6503 A/B via the 34.5kV SF6 disconnect switches by means of underground cables and to the 4.16kV and 13.8kV switchgear by means of metal enclosed bus ducts. Transformers have base rating from 5 MVA to 36 MVA and fan-cooled rating from 6.25 MVA to 53.6 MVA respectively. Normally each transformer in double ended switchgear will be supporting approximately one half of the total load connected to the switchgear depending on the downstream switching and the power users in operation. On single line operation of double ended switchgear, each transformer has the fan cooled capacity to support the total plant load connected to the switchgear. The cooling fans are automatically controlled and operation is initiated by temperature sensing devices within the transformers. The fan cooled rating of the transformers has not been utilized for the expansion project load requirements and is intended for future expansion. It is essential that cooling fans are available for operation at all times to enable each transformer to be immediately ready to supply the load when one of two transformers in double ended switchgear is lost. The transformer windings are housed in oil filled steel tanks with projecting cooling fins and conservator tanks. Page | 42 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 The transformers have separate primary and secondary windings connected in 'Delta' on the primary side and in 'Wye' on the secondary side. The center point of secondary winding 'Wye' connection are taken out and grounded through grounding resistors which are provided to limit the fault energy in any ground fault in the 4.16kV and 13.8kV system. The grounding resistors are mounted on top of the transformer tank. Each transformer is provided with off circuit tap changers operated by a switch handle, which is located in the transformer terminal box. These tap changers have four tap setting position of +/-2 1/2%, in addition to the center tap position, to enable the voltage to be adjusted. The voltage spread is optimized from no load to full load on the 4.16kV & 13.8kV and from no load to full load on the 4.16kV & 13.8kV switchgear. The optimum voltage spread is that the voltage at no load and the voltage at full load are within the voltage tolerances of the load equipment and materials. As the off load tap changer operating handles are located in the transformer terminal chambers it is necessary, in order to change the settings, to de-energize the transformers and tag out and lock out both primary and secondary circuit breakers before opening the terminal chambers. Medium Voltage Transformer Protection The 34.5/4.16kV and 34.5/13.8kV transformers are provided with two levels of protection. The first level of protection, commonly called primary protection, is very fast in operation and only responds to faults within a particular zone. The second level of protection commonly called secondary protection, is slower in operation and responds in a coordinated sequence for faults down stream from the protection device and provides back-up protection to the primary protection. Page | 43 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 The terms primary and secondary used in the above context are not to be confused with the same terms used to denote transformer windings i.e. primary winding, secondary winding, etc. The primary protection is provided by using Multilin Relay SR745, consists of differential protection (87T) as shown in Fig. 2.8.2.1 from which it will be noticed that for a fault within a zone both circuit breakers that could feed power into a fault are tripped. The zone numbers used in Fig. 2.8.2.1 are peculiar to this operating manual only. The secondary protection shown in Fig. 2.8.2.2 is provided by using Multilin Relay SR750, consists of instantaneous and inverse definite minimum time (50/51) and instantaneous, inverse over current, and transformer differential ground fault relays (50G, 51G, 87TG) which all trip their associated circuit breaker. In addition to the primary protection the transformers are provided with sudden pressure protection (63) of the transformer tanks. On the occurrence of an internal fault within the tank, which causes the production of gas, the pressure within the tank is relieved by a Qualitrol pressure relief device and a Buchholtz relay trips both circuit breakers that could feed power into the fault. Also in addition to these primary protection devices the transformers are provided with thermal protection (49) devices. These devices, which on the occurrence of an overload causing a temperature rise above the set point, will cause an alarm condition to enable operators to take the necessary action. As the primary protection only responds to faults within the protected zone, protection coordination is not involved. The secondary protection over current relays are set to coordinate with upstream and downstream protection devices such that in the event of a fault the nearest upstream protection device will operate first, to clear the fault from the power system, and thereby retain the maximum amount of equipment in service. Page | 44 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 The secondary ground fault relays are set to coordinated with upstream protection devices only as down stream ground faults do not appear in this part of the circuit as ground faults. Complete details of relay types, characteristics and settings are given in the Relay Coordination study for each unit. It is critical for reliable operation that the relays, settings and characteristics are checked on a regular basis. Page | 45 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 FOR 4.16KV AND 13.8KV ONE LINE DIAGRAMS SEE LIST BELOW 1 2 24 2PS-6503A 34.5 kV SWGR 2PS-6503B NC TRIP TRIP 34.5KV DISCONNECT 34.5KV DISCONNECT SW ITCHES SW ITCHES TYPICAL TRANSFORMERS 87T 86 ZONE 1 34.5KV/13.8KV ZONE 2 86 87T 34.5KV/4.16KV TRIP 1 TRIP 2 24 MV SWGR NO TYPCIAL 4.16KV & 13.8KV SWITCHGEAR 87T TRANSFORMER DIFFERENTIAL PROTECTION SEE 4.16KV & 13.8KV ONE LINE DRAWINGS 210-DP-002 ETHLYENE SUB 2PSU-1001 236-DP-027 POLYMER FINISHING SUB 2PSU-3601 220-DP-005 ETHLYENE GLYCOL SUB 2PSU-2001 236-DP-025 POLYMER FINISHING SUB 2PSU-3601 220-DP-006 ETHLYENE GLYCOL SUB 2PSU-2001 241-DP-004 POLYPROP REAC SUB 2PSU-4101 230-DP-005 POLYETH REAC SUB 2PSU-3001 265-DP-041 EAST OFFSITES SUB 2PSU-6503 230-DP-008 POLYETH REAC SUB 2PSU-3001 265-DP-031 WEST OFFSITES SUB 2PSU-6502 Figure 2.8.2.1 34.5kv/4.16kv & 13.8kv Transformer Primary Protection One Line Diagram Page | 46 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 FOR 4.16KV AND 13.8KV ONE LINE DIAGRAMS SEE LIST BELOW 1 2 24 2PS-6503A 34.5 kV SWGR 2PS-6503B TRIP NC TRIP 50 50 51 51 50G 50G 51G 51G 34.5KV DISCONNECT SW ITCHES 50P 51P 51P 50P 49 63 ZONE 1 ZONE 2 63 49 TYPICAL TRANSFORMERS ALARM 86 51G 51G 86 34.5KV/13.8KV ALARM 34.5KV/4.16KV 87 R R 87 TG TG 51S 51S TRIP 1 2 TRIP 24 MV SWGR NO TYPCIAL 4.16KV & 13.8KV SWITCHGEAR 50 50 INSTANTANEOUS OVERCURRENT 63 51 OVERCURRENT PROTECTION PRESSURE PROTECTION 50G GROUND FAULT PROTECTION 51 INVERSE TIME OVERCURRENT 49 THERMAL PROTECTION 51G 87 DIFFERENTIAL GROUND PROTECTION TG SEE 4.16KV & 13.8KV ONE LINE DRAWINGS 210-DP-002 ETHLYENE SUB 2PSU-1001 236-DP-027 POLYMER FINISHING SUB 2PSU-3601 220-DP-005 ETHLYENE GLYCOL SUB 2PSU-2001 236-DP-025 POLYMER FINISHING SUB 2PSU-3601 220-DP-006 ETHLYENE GLYCOL SUB 2PSU-2001 241-DP-004 POLYPROP REAC SUB 2PSU-4101 230-DP-005 POLYETH REAC SUB 2PSU-3001 265-DP-041 EAST OFFSITES SUB 2PSU-6503 230-DP-008 POLYETH REAC SUB 2PSU-3001 265-DP-031 WEST OFFSITES SUB 2PSU-6502 Figure 2.8.2.2 34.5kv/4.16kv & 13.8kv Transformer Secondary Protection One Line Diagram Page | 47 Classification: Internal Use 0 255 4 227 77 217 247 159 205 30 82 77 217 247 223 0 66 5 77 217 247 34.5kV/480V Transformers 34.5kV/480V Transformer Equipment The 34.5kV/0.48kV transformers are of ABB manufacture. The transformers are connected to their supply 34.5kV switchgear by means of cables and to the 480 volt switchgear by-means of metal enclosed bus ducts. The transformers have base ratings from 1.0 MVA to 2.0 MVA. All transformers are provided with cooling fans, which increase their base ratings by about 25%. See section 2.20 for system lim