CP Automatic capacitor bank

Transcription

1 CP Automatic capacitor bank STE-CP254_V2_général.doc Page 1

2 CP General presentation CP 254 is a range of MV capacitor banks designed to be used in electrical networks up to 36kV. The capacitor bank is made of unpainted aluminium or galvanised steel frame and panels, which is equipped with PROPIVAR capacitors, SF6 switch, unbalance current transformer and inrush current limiting reactors. The bank is arranged in double star connection and the unbalance current transformer has to be connected to a relay to insure the protection against capacitor internal fault. Several capacitor banks can be controlled by a power factor relay to make an automatic power factor correction system. Standards The CP 254 equipment is designed, manufactured, and tested according to the relevant IEC recommendations. High voltage capacitors IEC & 2, BS 1650, VDE 0560, C22-2 N 190-M1985, High voltage capacitors with internal fuses IEC , NFC , High voltage switch IEC 56 Reactors IEC 289 Current transformer IEC 185 Relays IEC 255 Technical characteristics CP 254 capacitor bank is made of unpainted aluminium or galvanised steel frames and panels. It is designed for the following installation conditions : indoor installation, altitude less than 1000m, average daily ambient temperature of between -25 C and +35 C, and a maximum of 40 C, The protection degree of the enclosure is IP 23. Available options for the enclosure : - Outdoor type enclosure, Electrical characteristics CP 254 capacitor bank ranges are available for voltage up to 36kV, for 50Hz or 60Hz network. STE-CP254_V2_général.doc Page 2

3 According to network rated voltage, the insulation level of equipment is as follows : Rated voltage (Vdim) (V) Insulation level (kv) Power freq. voltage withstand (kvrms) Impulse voltage withstand (kv peak) , The tolerance on the rated power of the capacitor bank is : 0/+10%, Capacitance variation according to temperature is : -3, / C Acceptable overcurrent and overvoltage : CP 254 capacitor banks are designed for : 1,10 x Un overvoltage - 12 hours per day, 1,15 x Un power frequency overvoltage - 30 minutes per day, Permanent overcurrent : 1,3 x In. Design voltage, design power and marking According to IEC recommendations, capacitor units or capacitor banks nameplates shall indicate the maximum power and voltage for which it is designed (Qdim & Vdim). Our capacitor units and capacitor banks have nameplates showing these design power and design voltage (Qdim and Vdim). Operating values can be equal or lower than these values (Qn and Vn). The documents supplied with our medium voltage products (price lists, order forms, catalogues, ) provide reactive power values for the most common network voltages. If the required voltage does not appear in the tables, it is possible to make a calculation using the formulae : Qn = (Vn/Vdim)² x Qdim Composition Each CP 254 capacitor bank includes the following components: Basic components : Unpainted aluminium or galvanised steel cubicle, IP23 for indoor installation, PROPIVAR capacitor units, (6,9 or 12 units, depending on the rated power of the bank) One switch, Three single-phase inrush current limiting reactors, One unbalance current transformer, The following items are available as options : Unbalance current relays (two relays must be used for banks using capacitors with internal fuses, one relay only for banks using capacitor units without internal fuses) Set of two quick discharge coils, Three pole grounding switch, Control and protection box, (if this option is used, it includes the unbalance protection relays) STE-CP254_V2_général.doc Page 3

4 General layout and single line diagram Enclosures The capacitor banks enclosures are made of unpainted aluminium or galvanised steel frames and panels. The banks are designed to include up to 12 capacitor units in double star connection. There are two types of enclosures : CP254-12C for voltages up to 24kV (BIL 125kV), CP254-12K for voltages up to 36kV (BIL 170kV), In CP254-12K, two capacitor units are connected in series in each branch of each star to reach the required rated voltage for the system. Capacitor units The capacitor units are connected in double star arrangement. Depending on the rated voltage and power of the capacitor units, they will be fiited with internal fuses. (In case the capacitor bank uses capacitor units without internal fuse, the description name includes the letter "S" (CP C-S or CP K-S)) The PROPIVAR capacitor units have the following characteristics: All film technology, Filled with biodegradable dielectric fluid, Single-phase connected, Fitted with two epoxy resin bushings, Fitted with internal discharge resistors (75V / 10min). According to IEC standard requirements, capacitor units include internal discharge resistors so that the residual voltage is less than 75V within 10 minutes after disconnection. Switch The capacitor bank is operated by a SF1 switch from Schneider-Electric range of switchgear. This switch uses SF6 as dielectric gas. It has been type tested for back to back capacitor switching and provides restrike free operation of capacitors. It is designed to make at least 5000 mechanical operations / electrical operations for this particular application. Reactors The reactors used are single-phase, dry type, with air core and natural air cooling. The rated current is equal or higher than 1,43 times the capacitor bank nominal current. The inductance value is calculated so that the peak inrush current value is lower than 100 times the nominal current of the capacitor bank, as per IEC recommendation. Current transformer The double star arrangement and unblance protection device requires the use of a specifc current transformer with a X/5A ratio. The CT used are epoxy resin type. The burden is 15VA. It is a measurement type CT with accuracy class : cl1. Unbalance protection relay Two (*) relays are used for unbalance protection. The first one gives an alarm when the quantity of internal fuses blown is just one below the maximum acceptable quantity. The second one makes the capacitor bank trip when the maximum acceptable quantity of internal fuses blown is reached. This double thresholds device allows preventive maintenance as the operator can organize the maintenance operation as soon as he sees the alarm information appear. (*) For CP254-12C-S and CP254-12K-S, using capacitor units without internal fuses, there is only one relay for immediat tripping after first internal fault. STE-CP254_V2_général.doc Page 4

5 Connections The connection supports are made of porcelain or epoxy resin. Connections are of bare copper bars. Low voltage wiring Low voltage wiring is insulated with black PVC, 1000 V grade, with the following cross-sections: 2,5 sq. mm for currents circuits, 1,5 sq. mm for voltage circuits. Each extremity of wire is marked using the independent marking system. Quick discharge coils (optional) Quick discharge coils allow a very fast discharge time (less than 10 s). Caution : In any case (without or with quick discharge coils), a time delay relay must be used to avoid connection of the capacitor bank within less than 5 minutes after its disconnection, either due to automatic control, protection tripping, voltage outage, Control and protection box (optional) There are five models of control and protection boxes available, for 1 up to 5 capacitor stages. (Capacitor banks automatically controlled by a power factor relay are called "stages"). These control and protection boxes are designed for indoor use only. They include the following devices : One Varlogic power factor controller, The unbalance protection relays, Signaling lamps : Voltage "on" For each stage : Stage "On", Stage "Off", Unbalance alarm, Unbalance tripping Optional : a local manual control switch. This switch has three positions : "Auto" : the stages are controlled by the power factor relay, "Manu" : the stages are manually controlled by a 2 position switch located on the control box, (1 switch per stage) "0" : the stages remain off all the time (no automatic nor manual operation permitted), Auxiliary voltages Here are the voltages which can be used for CP 254 capacitor banks : Control and signaling circuits (switch coils, lamps, auxiliary relays) : ac : 110Vac, 220/230Vac dc : 48Vdc, 110Vdc, 125Vdc, 220Vdc Switch motor : ac : 110Vac, 220/230Vac dc : 48Vdc, 110Vdc, 125Vdc, 220Vdc Power facor controller reference voltage : ac : 110Vac, 220/240Vac, 380/415Vac Operating conditions Internal fault protection : PROPIVAR capacitors have to be protected according to Rectiphase instructions. Unbalance protection settings (current and time delay settings) have to be adjusted according to instructions provided in the contractual documents (drawings, capacitor bank arragement and routine test certificates) Additional protections : To provide a suitable protection level for the equipment, the capacitor bank feeder must include the following additional protection devices : Short-circuit protection : recommended setting values : 3 x In / 0,1s, Overload protection : recommended setting values : 1,4 x In / 10s, Important note : The feeder circuit-breaker shall be suitable for capacitor current switching. STE-CP254_V2_général.doc Page 5

6 Factory tests Each CP 254 capacitor bank manufactured by Rectiphase must pass routine testing before delivery. The factory routine tests are performed according to IEC relevant recommendations and include the following : A) For PROPIVAR capacitor units : capacitance measurement, loss angle measurement (tg δ), sealing test, internal discharge resistor value checking, voltage test between terminals, voltage test between terminals and container, B) For CP254 capacitor banks : phase to phase capacitance measurement, insulation measurement, conformity checking, functional test (off-load operation), Documents The following documents are part of Rectiphase supply : three sets of routine test certificates (french / english) three sets of drawings and diagrams (french / english or french / spanish), one instruction manual (french / english / spanish) STE-CP254_V2_général.doc Page 6