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Technical guide VUC

 

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1ZSC000562-AAX en, Rev. 1

Coarse/fine regulation leakage inductance switching

When changing from the end of the fine winding to the end of 
the coarse winding, a high leakage inductance can be set up 
with the two windings in series. The critical moment occurs at 
switching the tap-changers mechanical mid-position, as the 
circulating current passes through not only one loop but also 
the entire coarse and fine tap winding.

The leakage inductance that occurs from one loop, Fig. 44, 
is negligible but can be substantial from the complete coarse 
and fine winding, Fig. 45.

This leakage inductance causes a phase shift between 
switching current and recovery voltage that makes the 
breaking more severe. The tap-changer must be dimensioned 
accordingly. The leakage inductance shall be specified in the 
ordering data sheet.

For certain winding configurations, such as coarse and fine 
windings located axially, this value might be very high. For 
more information, see IEC 60214-2, 2004-10, or consult ABB 
for advice.

Fig. 44. Normal operation.

Fig. 45. Operation with high leakage inductance.

Tie-in resistor and tie-in resistor switch

When the change-over selector operates, the tapped winding 
is disconnected for a short time. The voltage of that winding 
is then determined by the voltage of, and the capacitances 
to, the surrounding windings or tank wall/core. For certain 
winding layouts, voltages and capacitances, the capacitive 
controlled voltage will reach magnitudes that are too high for 
the change-over selector. In these cases potential controlling 
resistors, so called tie-in resistors, should be connected 
according to Fig. 46.

The tie-in resistor is connected between the middle of the 
tapped winding and the connection point on the bottom 
of the diverter switch housing. This means that power is 
continuously dissipated in the resistors that add to the no-
load losses of the transformers. The resistors must also be 
dimensioned for the power dissipation.

The tie-in resistors are normally mounted separately from 
the tap-changer but can be mounted under the tap selector 
provided that tie-in resistor switch is not used. Please contact 
ABB for advice in such cases.

Main 
winding

Main 
winding

Coarse 
winding

Coarse 
winding

Fine 
winding

Fine 
winding

Summary of Contents for VUCG.B

Page 1: ...On load tap changers type VUC Technical guide 1ZSC000562 AAX en Rev 1 ...

Page 2: ...entative ABB makes no warranty or representation and assumes no liability for the accuracy of the information in this document or for the use of such information All information in this document is subject to change without notice This document must not be copied without our written permission and the contents thereof must not be imparted to a third party nor be used for any unauthorized purpose C...

Page 3: ...d the electrical connection are correctly realized by the manufacturer of the transformer e g in compliance with our Installation Instructions and EMC Directive 89 336 EEC regarding the intrinsic characteristics to emission and immunity levels and Low Voltage Directive 73 23 EEC modified by Directive 93 68 EEC concerning the built in motor and apparatus in the control circuits Certificate of Incor...

Page 4: ...of connection 17 Three phase neutral point N 17 Single phase E 17 Three phase delta B 17 Three phase fully insulated delta T 17 Three phase fully insulated auto transformer T 17 Tap changer characteristics and technical data 18 Type designation 18 Type of tap changer 18 Type of regulation 18 Type of connection 18 Impulse withstand voltage to earth 18 Maximum rated through current 18 Tap selector s...

Page 5: ...hanism 31 Design 31 Installation 31 Maintenance 31 Operating shafts 31 Dimensions 33 Dimensions type VUCG 33 Type VUCG E and VUCG N with tap selector type C and cover mounting 34 Type VUCG E and VUCG N with tap selector III and with tie in resistor switch 35 Type VUCG E and VUCG N with tap selector F and with tie in resistor switch 36 Type VUCG R and VUCG B with tap selector F and with tie in resi...

Page 6: ...h Fig 1 Main parts on load tap changers type VUC Design principles is mounted beneath the diverter switch housing consists of the fine tap selector and usually also of a change over selector Power to operate the tap changer is supplied from the motor drive mechanism which is mounted on the outside of the transformer The power is transmitted by means of shafts and bevel gears The VUC diverter switc...

Page 7: ... flanges x4 Top section Shielding ring Current terminal Bottom section Valve for use at processing Bushings connecting from the tap selector Insulating cylinder Diverter switch Oil draining tube Intermediate gear Driving disc for the diverter switch Guide pins Shielding ring Insulating shaft Bevel gear with position indicator Buffer springs Flange for connection to gas operated relay transformer m...

Page 8: ...m interrupters and auxiliary contacts The auxiliary contacts are also able to break the load current in the unlikely event that a vacuum interrupter failure should occur For VUCG in service position the load current is transferred through the auxiliary contacts and the vacuum interrupters All current carrying contacts are made of low resistance material For VUCL in service position the load curren...

Page 9: ...t contact fingers each The fingers make contact at one end with the fixed contact and at the other with the current collector The moving contacts slide on the fixed contacts and the current collector rings giving a wiping action which makes the contacts self cleaning This arrangement promotes good conductivity and negligible contact wear Fig 4 Tap selectors size C size III and size F The tap selec...

Page 10: ...ble in two designs one for cover mounting and one for pre mounting yoke mounting on the transformer s active part The diverter switch housings have high quality seals that guarantee vacuum and overpressure proof performance under all service conditions In case of material ageing after extremely long service the seals can be re tightened from the inside of the housing The bottoms and heads of the c...

Page 11: ...r is available on request Special shaft systems are also available on request Transition resistors The transition resistors are made of wire and located above the diverter switch contacts The resistors are robust and designed to last the lifetime of the mechanism under normal service conditions Special applications load conditions and environments Please contact ABB for advice in the following cas...

Page 12: ...ain vacuum interrupter MVI and hence let the current flow through the transition resistor TR Fig 9 The main contact MC is then rotated Figs 10 and 11 in order to connect to v The main vacuum interrupter then closes leading to an associated circulating current driven by the difference in voltage potential Fig 12 The load current is now via the normal path from v to the neutral point The voltage is ...

Page 13: ... guide VUC 13 MVI MC RVI TR RC x v MVI MC RVI TR RC x v MVI MC RVI TR RC x v MVI MC RVI TR RC x v MVI MC RVI TR RC x v MVI MC RVI TR RC x v MVI MC RVI TR RC x v MVI MC RVI TR RC x v Fig 8 Fig 9 Fig 10 Fig 11 Fig 12 Fig 13 Fig 14 Fig 15 ...

Page 14: ... contact BPC Figs 17 and 18 Next is to open the main vacuum interrupter MVI and hence let the current flow through the Fig 16 Fig 17 Fig 18 Fig 19 transition resistor TR Fig 19 The main contact MC is then rotated Figs 20 and 21 in order to connect to v The main vacuum interrupter then closes leading to an associated circulating current driven by the difference in voltage potential Fig 22 The load ...

Page 15: ... MC RVI TR RC BPC x v MVI MC RVI TR RC BPC x v MVI MC RVI TR RC BPC x v MVI MC RVI TR RC BPC x v MVI MC RVI TR RC BPC x v MVI MC RVI TR RC BPC x v MVI MC RVI TR RC BPC x v MC RVI TR RC BPC x v MVI Fig 20 Fig 21 Fig 22 Fig 24 Fig 23 Fig 25 Fig 27 Fig 26 ...

Page 16: ...s switching type R The change over selector extends the regulating range to twice the voltage of the tapped winding by connecting the main winding to different ends of the regulating winding and thereby reversing the magnetic flux generated by the regulating winding See Fig 29 Change over selector for coarse fine switching type D In type D switching the change over selector extends the regulating ...

Page 17: ...ll three phases The transformers neutral point is in the tap changer Single phase E Only one unit is required Three phase delta B Two units required Driven by a common motor drive One unit common for two phases Three phase fully insulated delta T Three units required Driven by a common motor drive Fig 31 Fig 32 Fig 33 Fig 34 ...

Page 18: ...delta two units single phase and two phase Impulse withstand voltage to earth VUCG 380 kV 650 kV 750 kV 1050 kV VUCL 380 kV 650 kV 750 kV 1050 1175 kV Maximum rated through current See tables for diverter switches and tap selectors respectively The lowest rating of the two determines the overall rating Tap selector size C tap selector for VUCG only III tap selector for VUCG and VUCL F tap selector...

Page 19: ...ications two or more poles of a tap changer or more than one tap changer can work in parallel However it is important to implement this in a correct way There is a difference between whether it should work in position not during operation only or if it should work during operation During operation Enforced current splitting during operation can be used when the diverter switch has a lower current ...

Page 20: ...iverter switch The rated phase step voltage is a function of the rated through current as shown in the diagrams below Fig 36 Rated phase step voltage for type VUCG Fig 37 Rated phase step voltage for type VUCL VUCL N B E T Step voltage V Rated through current A VUCG in the short version has a 220 mm shorter diverter switch housing see dimension drawings in this document For short versions there mi...

Page 21: ... excellent breaking performance of the vacuum interrupters It shall however be calculated for every case Contact life The contact life for VUC type of tap changers is always 600 000 operations regardless of the rated through current The contact life is stated on the rating plate Standards and testing The on load tap changers made by ABB fulfill the requirements according to IEC 60214 1 2014 05 1 a...

Page 22: ...t is not an IEC value a1 Between any electrically adjacent contacts in the tap selector not connected a2 Between the ends of the fine regulating winding across range For coarse fine switching in minus position this means between the freely oscillating end of the coarse winding and any end of the fine winding b1 Between not connected taps of different phases in the fine selector b2 Between open con...

Page 23: ... 350 140 D 32 35 250 95 350 140 350 140 350 140 100 20 100 20 300 125 350 140 Table 5 VUCG with tap selector III unshielded version All values given as 1 2 50 µs impulse withstand voltage kV power frequency withstand voltage kV Type of regulation No of positions Within one phase Between phases for neutral point a1 a2 c1 f1 f2 e1 b2 b1 d1 L 14 300 125 490 150 100 20 100 20 500 160 L 15 16 300 125 4...

Page 24: ...5 300 125 400 150 100 20 100 20 550 180 D 11 300 125 550 180 600 200 600 200 600 200 100 20 100 20 550 180 600 200 D 12 13 300 125 480 160 600 200 600 200 600 200 100 20 100 20 550 180 600 200 D 14 15 300 125 400 150 600 200 600 200 600 200 100 20 100 20 550 180 600 200 D 16 27 300 125 550 180 600 200 600 200 600 200 100 20 100 20 550 180 600 200 D 28 31 300 125 480 160 600 200 600 200 600 200 100...

Page 25: ...500 160 600 200 D 32 35 300 125 350 140 600 200 600 200 600 200 100 20 100 20 500 160 600 200 Table 9 VUCL with tap selector III shielded version All values given as 1 2 50 µs impulse withstand voltage kV power frequency withstand voltage kV Type of regulation No of positions Within one phase Between phases for neutral point a1 a2 c1 f1 f2 e1 b2 b1 d1 L 14 300 125 550 180 100 20 100 20 550 180 L 1...

Page 26: ...30 III 450 600 700 800 N B E T 9 23 F 450 600 700 800 N B E T 9 23 VUCL III 700 1000 N B E T 12 30 III 1300 E T 16 40 F 700 1000 1300 N B E T 16 40 Table 12 1 In case of VUC E T higher values are possible on request 2 For times longer than 3 s contact ABB for advice VUCL with tap selector F All values given as 1 2 50 µs impulse withstand voltage kV power frequency withstand voltage kV Type of regu...

Page 27: ...t these requirements the VUC models have been designed so that the contact temperature rise over the surrounding oil does not exceed 20 K when loaded with a current of 1 2 times the maximum rated through current of the tap changer The contact life stated on the rating plate is given with the consideration that currents of maximum 1 5 times the rated through current occur in a maximum of 3 of the t...

Page 28: ...4 Normal operation Fig 45 Operation with high leakage inductance Tie in resistor and tie in resistor switch When the change over selector operates the tapped winding is disconnected for a short time The voltage of that winding is then determined by the voltage of and the capacitances to the surrounding windings or tank wall core For certain winding layouts voltages and capacitances the capacitive ...

Page 29: ... resistor switch is available only for tap selector III and F Diverter switch Tie in resistor switch Tie in resistor Tap selector Main winding Regulating winding with change over selector Fig 46 Tie in resistor example Fig 47 Example of winding layout and information When ordering give the winding layout and information according to the example in Fig 47 and Table 13 and ABB will calculate whether...

Page 30: ...627 500 730 Table 16 Weights for type VUCG On load tap changer type designation Required oil in kg Selector III Selector F BIL Current Without oil Total Without oil Total VUCL N 380 700 1300 260 495 755 625 885 650 700 1300 300 505 805 642 942 1050 700 1300 340 525 865 662 1002 VUCL T 380 700 1300 780 1266 2046 1425 2205 650 700 1300 900 1296 2196 1605 2505 1050 700 1300 1020 1356 2376 1665 2685 V...

Page 31: ...oad and environment it is recommendable to perform one maintenance cleaning and inspection during the transformer life The figure of 15 years stated on the rating plate is provided as a guideline For more details see the appropriate Maintenance guide Pressure During drying the tap changers diverter switch housing should have no pressure difference to the transformer This is obtained by opening the...

Page 32: ...2 Technical guide VUC 1ZSC000562 AAX en Rev 1 Fig A L1 VUCG N E VUCL N E Fig B L1 Fig C L3 L1 VUCG B VUCL B Fig D L1 L3 Fig E L4 L3 L1 VUCG T VUCL T Fig F L1 L3 L4 Fig 49 Designation of operating shafts ...

Page 33: ...s For on load tap changer type Max rated through current A H2 size C mm H2 size III mm H2 size F mm VUCG N 450 600 959 1160 1491 450 800 1160 1491 VUCG E VUCG T 5 450 600 519 552 791 601 800 739 552 791 VUCG B 6 450 600 Single phase 519 Two phase 739 Single phase 552 Two phase 856 Single phase 791 Two phase 1141 VUCG B 6 601 800 Single phase 552 Two phase 856 Single phase 791 Two phase 1141 Table ...

Page 34: ...mensions type VUCG E and VUCG N with tap selector type C and cover mounting C L Tap selector C L Diverter switch Section A A Plus Minus and Coarse Fine switching Section A A Linear switching Type VUCG E and VUCG N with tap selector type C and cover mounting ...

Page 35: ...ie in resistor switch Fig 51 Dimensions type VUCG E and VUCG N with tap selector III and with tie in resistor switch Model for mounting on transformer s active part Model for cover mounting C L Diverter switch C L Tap selector Section A A Linear switching Section A A Plus Minus and Coarse Fine switching ...

Page 36: ...36 Technical guide VUC 1ZSC000562 AAX en Rev 1 Fig 52 Dimensions type VUCG E with tap selector F and with tie in resistor switch Type VUCG E with tap selector F and with tie in resistor switch ...

Page 37: ...chnical guide VUC 37 Fig 53 Dimensions type VUCG B with tap selector F and with tie in resistor switch Design for premounting on the active part of the transformer Type VUCG B with tap selector F and with tie in resistor switch ...

Page 38: ...sings For tap changer type Max rated through current A H2 size III mm H2 size F mm VUCL N 700 1000 1300 1160 1491 VUCL E T 5 700 1000 552 791 1300 856 791 VUCL B 6 700 1000 1300 Single phase unit H22 552 Single phase unit H22 791 Two phase unit H21 856 Two phase unit H21 1141 Table 22 Tap selectors 1 Shielding rings are used only for insulation levels 650 275 kV and higher 2 Space required for lif...

Page 39: ...Fig 54 Dimensions type VUCL E and VUCL N with tap selector III and with tie in resistor switch Section A A Plus Minus and Coarse Fine switching Section A A Linear switching Type VUCL E and VUCL N with tap selector III and with tie in resistor switch ...

Page 40: ...00562 AAX en Rev 1 Fig 55 Dimensions type VUCL B with tap selector III and with tie in resistor switch Design for premounting on the active part of the transformer Type VUCL B with tap selector III and with tie in resistor switch ...

Page 41: ...al guide VUC 41 Fig 56 Dimensions type VUCL E and VUCL N with tap selector F and with tie in resistor switch Section A A Plus Minus and Coarse Fine switching Type VUCL E and VUCL N with tap selector F and with tie in resistor switch ...

Page 42: ...C000562 AAX en Rev 1 Fig 57 Dimensions type VUCL B with tap selector F and with tie in resistor switch Design for premounting on the active part of the transformer Type VUCL B with tap selector F and with tie in resistor switch ...

Page 43: ...1ZSC000562 AAX en Rev 1 Technical guide VUC 43 49 1274 1197 37 45 79 383 626 475 202 75 213 408 1050 640 171 216 624 390 77 Fig 58 Dimensions motor drive mechanisms BUL2 BUE2 Motor drive mechanisms ...

Page 44: ...ken until the first maintenance stop without filling up with new oil 3 It is recommended to install the oil sampling valve with piping accessible from ground level so that oil samples can be taken without disconnecting the transformer 4 X corresponds to a height giving a max recommended pressure difference between the tap changer diverter switch housing and the transformer tank of 50 kPa 5 H corre...

Page 45: ...es Single phase diagrams The tap changer can also be connected in such a way that position 1 gives a minimum effective number of turns in the transformer winding with the tap changer in position 1 Even positions when having change over selector is made by blocking one position in the motor drive Appendix 1 Single phase diagrams for VUCG C Linear Plus Minus Coarse Fine 4 steps Number of loops 4 Num...

Page 46: ...ams for VUCG C Linear Plus Minus Coarse Fine 7 steps Number of loops 7 Number of tap positions 8 8 steps Number of loops 8 4 4 4 Number of tap positions 9 9 9 9 steps Number of loops 9 Number of tap positions 10 10 steps Number of loops 10 5 5 5 Number of tap positions 11 11 11 ...

Page 47: ...or VUCG C Linear Plus Minus Coarse Fine 11 steps Number of loops 11 Number of tap positions 12 12 steps Number of loops 12 6 6 6 Number of tap positions 13 13 13 13 steps Number of loops 13 Number of tap positions 14 14 steps Number of loops 14 7 7 7 Number of tap positions 15 15 15 ...

Page 48: ... for VUCG C Linear Plus Minus Coarse Fine 15 steps Number of loops 15 Number of tap positions 16 16 steps Number of loops 16 8 8 8 Number of tap positions 17 17 17 17 steps Number of loops 17 Number of tap positions 18 18 steps Number of loops 10 9 10 Number of tap positions 19 19 ...

Page 49: ...G C Linear Plus Minus Coarse Fine 20 steps Number of loops 10 10 10 Number of tap positions 21 21 22 steps Number of loops 12 11 12 Number of tap positions 23 23 24 steps Number of loops 12 12 12 Number of tap positions 25 25 26 steps Number of loops 14 13 14 Number of tap positions 27 27 ...

Page 50: ...G C Linear Plus Minus Coarse Fine 28 steps Number of loops 14 14 14 Number of tap positions 29 29 30 steps Number of loops 16 15 16 Number of tap positions 31 31 32 steps Number of loops 16 16 16 Number of tap positions 33 33 34 steps Number of loops 18 17 18 Number of tap positions 35 35 ...

Page 51: ...diagrams for VUCG III and VUCL III Linear Plus Minus Coarse Fine 4 steps Number of loops 4 Number of tap positions 5 5 steps Number of loops 5 Number of tap positions 6 6 steps Number of loops 6 Number of tap positions 7 7 steps Number of loops 7 Number of tap positions 8 ...

Page 52: ...UCG III and VUCL III Linear Plus Minus Coarse Fine 8 steps Number of loops 8 4 4 4 Number of tap positions 9 9 9 9 steps Number of loops 9 Number of tap positions 10 10 steps Number of loops 10 5 5 5 Number of tap positions 11 11 11 11 steps Number of loops 11 Number of tap positions 12 ...

Page 53: ...III and VUCL III Linear Plus Minus Coarse Fine 12 steps Number of loops 12 6 6 6 Number of tap positions 13 13 13 13 steps Number of loops 13 Number of tap positions 14 14 steps Number of loops 14 7 7 7 Number of tap positions 15 15 15 15 steps Number of loops 15 Number of tap positions 16 ...

Page 54: ...II and VUCL III Linear Plus Minus Coarse Fine 16 steps Number of loops 16 8 8 8 Number of tap positions 17 17 17 17 steps Number of loops 17 Number of tap positions 18 18 steps Number of loops 18 10 9 10 Number of tap positions 19 19 19 19 steps Number of loops 19 Number of tap positions 20 ...

Page 55: ...and VUCL III Linear Plus Minus Coarse Fine 20 steps Number of loops 20 10 10 10 Number of tap positions 21 21 21 21 steps Number of loops 21 Number of tap positions 22 22 steps Number of loops 12 11 12 Number of tap positions 23 23 24 steps Number of loops 12 12 12 Number of tap positions 25 25 ...

Page 56: ...d VUCL III Linear Plus Minus Coarse Fine 26 steps Number of loops 14 13 14 Number of tap positions 27 27 28 steps Number of loops 14 14 14 Number of tap positions 29 29 30 steps Number of loops 16 15 16 Number of tap positions 31 31 32 steps Number of loops 16 16 16 Number of tap positions 33 33 ...

Page 57: ...1ZSC000562 AAX en Rev 1 Technical guide VUC 57 Appendix 2 Single phase diagrams for VUCG III and VUCL III Linear Plus Minus Coarse Fine 34 steps Number of loops 18 17 18 Number of tap positions 35 35 ...

Page 58: ...e diagrams for VUCG F and VUCL F Linear Plus Minus Coarse Fine 4 steps Number of loops 4 Number of tap positions 5 5 steps Number of loops 5 Number of tap positions 6 6 steps Number of loops 6 Number of tap positions 7 7 steps Number of loops 7 Number of tap positions 8 ...

Page 59: ... VUCG F and VUCL F Linear Plus Minus Coarse Fine 8 steps Number of loops 8 4 4 4 Number of tap positions 9 9 9 9 steps Number of loops 9 Number of tap positions 10 10 steps Number of loops 10 5 5 5 Number of tap positions 11 11 11 11 steps Number of loops 11 Number of tap positions 12 ...

Page 60: ...G F and VUCL F Linear Plus Minus Coarse Fine 12 steps Number of loops 12 6 6 6 Number of tap positions 13 13 13 13 steps Number of loops 13 Number of tap positions 14 14 steps Number of loops 14 7 7 7 Number of tap positions 15 15 15 15 steps Number of loops 15 Number of tap positions 16 ...

Page 61: ...F and VUCL F Linear Plus Minus Coarse Fine 16 steps Number of loops 16 8 8 8 Number of tap positions 17 17 17 17 steps Number of loops 17 Number of tap positions 18 18 steps Number of loops 10 9 10 Number of tap positions 19 19 20 steps Number of loops 10 10 10 Number of tap positions 21 21 ...

Page 62: ...d VUCL F Linear Plus Minus Coarse Fine 22 steps Number of loops 12 11 12 Number of tap positions 23 23 24 steps Number of loops 12 12 12 Number of tap positions 25 25 26 steps Number of loops 14 13 14 Number of tap positions 27 27 28 steps Number of loops 14 14 14 Number of tap positions 29 29 ...

Page 63: ...gle phase diagrams for VUCG F and VUCL F Linear Plus Minus Coarse Fine 30 steps Number of loops 16 15 16 Number of tap positions 31 31 32 steps Number of loops 16 16 16 Number of tap positions 33 33 34 steps Number of loops 18 17 18 Number of tap positions 35 35 ...

Page 64: ...Copyright 2015 ABB All rights reserved 1ZSC000562 AAX en Rev 1 2015 04 15 ABB AB Components SE 771 80 Ludvika Sweden Phone 46 240 78 20 00 Fax 46 240 121 57 E Mail sales se abb com www abb com electricalcomponents ...

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