Appendix D - GSU2 Documents.pdf

GSU #2 Photos:

Photo 1: GSU #2 Tap Changer

Photo 2: GSU #2

Photo 3: GSU #2

Photo 4: GSU #2

OFF-CIRCUIT TAP CHANGER

type PBVK and PBVE ЕА 712e

TECHNICAL DATA Page.1 /17

OFF-CIRCUIT TAP-CHANGER

TECHNICAL DATA Page.2 /17

CONTENTS

1. GENERAL ……………………………………………………………………3

2. SURVEY ………………………………………………………………………7

3. DESIGNATION………………………………………………………………..9

4. CHARACTERISTICS………………………………………………………..12

5. SPECIAL DESIGN…..…………………………… …………………………12

6. INSTALLATION…………….…………………………… …………………16

7. DRIVE………………………….………………………………………………16

8. APPENDIX……………………….……………………………………………17

TECHNICAL DATA Page.3 /17

This catalogue presents the main characteristics and basic technical parameters of Hyundai Heavy Industries Co, Bulgaria (HHI-B) off-circuit tap changers. The presented technical information and data are intended mostly for transformer designers and all other engineers involved in the manufacturing, testing, erection, commissioning and maintenance of transformers equipped with off-circuit tap changers.

The most proper type of off-circuit tap changers can be selected with help of this catalogue. Usually the selected type of off-circuit tap changers and all necessary additional technical information have to be filled in the provided by HHI-B Order Specification Sheet.

The off-circuit tap changers is manufactured and delivered in accordance with the confirmed by the client Order Specification Sheet.

The selection of off-circuit tap changers, the technical data and properties stipulated in the Order Specification Sheet is transformer manufacturer responsibility since the requirements of transformer specification have to be met.

1. GENERAL

The off–circuit tap changers are used to regulate the voltage of power transformers within certain limits. The regulation is to be made only at fully disconnected state of the transformer.

The product works normally in transformer oil.

Off–circuit tap changers represented in this catalogue is mounted to the cover of the transformer.

Off–circuit tap changer has two basic types:

� PBVK – round type � PBVE – elliptic type

These types are designed on the basis of series “ PBV “, which are manufactured by HHI-B and mainly intended to be mounted in the space between the transformer windings columns.

All of the basic connections of the transformers can be implemented with the PBV; they are given in fig.1.

The basic types of PBVK and PBVE, their technical data and applications are given in table view –See fig.2a, fig.2b and page 4.

TECHNICAL DATA Page.4 /17

V

DOUBLE−BRIDGING OFF−CIRCUIT

STAR−DELTA OFF−CIRCUIT TAP CHANGER

Fig.1 OFF−CIRCUIT TAP CHANGER TYPE PBV − BASIC CONNECTIONS

TAP CHANGER

1V

V1

N

N

U

12 2

FOR NEUTRAL APPLICATION

OFF−CIRCUIT TAP CHANGER

2(N)

8 6

TAP CHANGER

N

UW1

N

W N

SINGLE−BRIDGING OFF−CIRCUIT TAP

SERIES−PARALLEL OFF−CIRCUIT

CHANGER

5 5

TECHNICAL DATA Page.5 /17

PBVK01 PBVK02 PBVK03

17.5 24.0 41.5 72.5 123 17.5 24 41.5 72.5 123 170 17.5 24.0 41.5 72.5

For neutral application, Y 832 852 922 1052 1232 918 978 1028 1138 1338 1848 744 764 834 964

Single-bridging, ME 832 892 982 1252 1672 918 978 1068 1338 1758 744 804 894 1164

Star-delta, Y/D 814 874 900 960 1050 744

Fig 2a OFF-CIRCUIT TAP CHANGER – OVERALL DIMENSIONS

PBVK01 (200−630) A PBVK02 (200−1000) A PBVK03 (200−630) A

0VERALL DIMENSIONS

PBVK

TECHNICAL DATA Page.6 /17

PBVE01 PBVE02

24 41.5 72.5 123 24 41.5 72.5 123 170

For neutral application, Y 852 922 1052 1232 978 1028 1158 1338 1848

Single-bridging, ME 892 982 1252 1672 978 1068 1338 1758

Double-bridging, MD 918 1038 1398 978 1098 1458

Series-parallel, S/P 900 1020 960 1080

Star-delta, Y/D 900 1020 960 1080

Fig.2b OFF-CIRCUIT TAP CHANGER - OVERALL DIMENSIONS

2.SURVEY

PBVE0 1 (200−630 ) A PBVE0 1 (200−1000 ) A

0VERALL D IM ENS IONS

PBVE

TECHNICAL DATA Page.7 /17

2.1 OFF-CIRCUIT TAP CHANGER

Rated current, A 200 400 630 1000

Thermal, short circuit current 3s, kA 4 8 12.6 15

Dynamic ,short circuit current, kA 10 20 31.5 37.5

Rated frequency Hz 50-60

Rated voltage, kV 10 20 35 60 110 150 220

Highest voltage, for equipment kV 17.5 24 41.5 72.5 123 170 245

Rated impulse withstand voltage,1.2/50µs kV 95 125 250 350 550 750 1050

Rated power frequency withstand voltage 50Hz kV

40 50 110 140 230 325 460

2.1.1.Type-PBVK (Withstand voltages for the internal insulation-see Table 1) Table 1

Type off-circuit tap changer

Insulation class kV

Rated current

A

Operating positions

Number of poles

Basic connections

Overall dimensions

PBVK 01-3-06050 Y,ME 17.5 - 123 200-630 5 3 Y,ME 701.01

PBVK 01-2-06050 Y,ME 17.5 - 123 200-630 5 2 Y,ME 701.02

PBVK 01-1-06050 17.5 - 123 200-630 5 1 Y,ME 701.03

PBVK 01-3-12110 Y,ME 17.5 - 123 200-630 11 3 Y,ME 701.04

PBVK 01-2-12110 Y,ME 17.5 - 123 200-630 11 2 Y,ME -

PBVK 01-1-12110 17.5 - 123 200-630 11 1 Y,ME -

PBVK 01-3-Y/D 17.5 - 24 200-630 2 3 Y/D 701.50

PBVK 02-3-06050 Y,ME 17.5 - 123 200-630 5 3 Y,ME 702.01

PBVK 02-2-06050 Y,ME 17.5 - 123 200-630 5 2 Y,ME 702.02

PBVK 02-1-06050 17.5 - 245 200-630 5 1 Y,ME 702.03

PBVK 02-3-16150 Y,ME 17.5 - 123 200-630 15 3 Y,ME 702.04

PBVK 02-2-16150 Y,ME 17.5 - 170 200-630 15 2 Y,ME -

PBVK 02-1-16150 17.5 - 245 200-630 15 1 Y,ME -

PBVK 02-3-Y/D 17.5 – 41.5 200-630 2 3 Y/D 702.50

PBVK 02-3-06050 Y,ME 17.5 - 123 1000 5 3 Y,ME 702.71

PBVK 02-2-06050 Y,ME 17.5 - 170 1000 5 2 Y,ME 702.72

PBVK 02-1-06050 17.5 - 245 1000 5 1 Y,ME 702.73

PBVK 02-3-12110 Y,ME 17.5 - 123 1000 11 3 Y,ME 702.74

PBVK 02-2-12110 Y,ME 17.5 - 170 1000 11 2 Y,ME -

PBVK 02-1-12110 17.5 - 245 1000 11 1 Y,ME -

PBVK 02-3-Y/D 17.5 – 41.5 1000 2 3 Y/D 702.80

PBVK 03-3-06050 Y,ME 17.5 – 72.5 200-630 5 3 Y,ME 703.01

PBVK 03-2-06050 Y,ME 17.5 – 72.5 200-630 5 2 Y,ME 703.02

PBVK 03-1-06050 17.5 – 72.5 200-630 5 1 Y,ME 703.03

PBVK 03-3-12110 Y,ME 17.5 – 72.5 200-630 11 3 Y,ME 703.04

PBVK 03-2-12110 Y,ME 17.5 – 72.5 200-630 11 2 Y,ME -

PBVK 03-1-12110 17.5 – 72.5 200-630 11 1 Y,ME -

PBVK 03-3-Y/D 17.5 200-630 2 3 Y/D 703.50

2.1.2. Type – PBVE (Withstand voltages for the internal insulation-see Table 2) Table 2

TECHNICAL DATA Page.8 /17

Type off-circuit tap changer

Insulation class kV

Rated current

A

Operating positions

Number of poles

Basic connections

Overall dimensions

PBVЕ 01-3-06050 Y,ME 24 - 123 200-630 5 6 Y,ME 705.01

PBVЕ 01-2-06050 Y,ME 24 - 170 200-630 5 4 Y,ME 705.02

PBVЕ 01-1-06050 24 - 245 200-630 5 2 Y,ME 705.03

PBVЕ 01-3-06050 MD 24 - 123 200-630 5 6 MD 705.04

PBVЕ 01-2-06050 MD 24 - 170 200-630 5 4 MD 705.05

PBVЕ 01-1-06050 MD 24 - 245 200-630 5 2 MD 705.06

PBVЕ 01-3-Y/D 24 - 41.5 200-630 2 6 Y/D 705.50

PBVЕ 01-3-S/P 24 - 41.5 200-630 2 6 S/P 705.51

PBVЕ 02-3-06050 Y,ME 24 - 123 200-630 5 6 Y,ME 706.01

PBVЕ 02-2-06050 Y,ME 24 - 170 200-630 5 4 Y,ME 706.02

PBVЕ 02-1-06050 24 - 245 200-630 5 2 Y,ME 706.03

PBVЕ 02-3-06050 MD 24 - 123 200-630 5 6 MD 706.04

PBVЕ 02-2-06050 MD 24 - 170 200-630 5 4 MD 706.05

PBVЕ 02-1-06050 MD 24 - 245 200-630 5 2 MD 706.06

PBVЕ 02-3-Y/D 24 - 41.5 200-630 2 6 Y/D 706.50

PBVЕ 02-3-S/P 24 - 41.5 200-630 2 6 S/P 706.51

PBVЕ 02-3-06050 Y,ME 24 - 123 1000 5 6 Y,ME 706.71

PBVЕ 02-2-06050 Y,ME 24 - 170 1000 5 4 Y,ME 706.72

PBVЕ 02-1-06050 24 - 245 1000 5 2 Y,ME 706.73

PBVЕ 02-3-06050 MD 24 - 123 1000 5 6 MD 706.74

PBVЕ 02-2-06050 MD 24 - 170 1000 5 4 MD 706.75

PBVЕ 02-1-06050 MD 24 - 245 1000 5 2 MD 706.76

PBVЕ 02-3-Y/D 24 - 41.5 1000 2 6 Y/D 706.90

PBVЕ 02-3-S/P 24 - 41.5 1000 2 6 S/P 706.91

2.2 DRIVE

Manual drive type ZR 03 – Drawing ZR – 03/03. It is mounted on the transformer tank wall.

Motor drive type MZ 4.9 – Drawing MZ – 4.9/07. It is mounted on the transformer tank wall.

3. DESIGNATION

TECHNICAL DATA Page.9 /17

3.1 Designation of one given type PBVK and PBVE

The PBVK and PBVE is determined with regard to type of series, number of poles, rated through current, rated voltage to ground and basic connection diagram. A designation example of a determined type of PBVK is given in fig.3.

PBVK01 3 200 41.5 06 05 0 Y

Fig 3

3.2 Designations of the symbols of the basic connection:

06 - number of contacts ( 3, 4, 6, …16 ) 05 - number of operating positions ( 2, 5, …15 ) 0 - number of mid positions

Y - basic connection ( Y, ME, MD, S/P, Y/D, P ( Y, ME, Y/D ) ):

- Y – for neutral point connection

- ME – single bridging

- MD – double bridging

- S/P – series - parallel

- Y/D – star / delta

- P(*) – parallel windings ( Y, ME, Y/D )

Basic circuit diagrams are given in fig.4.

3.3 Connecting terminals and operating positions

In each individual case a diagram is issued, which is required for the connection of off-circuit tap changer to the transformer. The diagrams determinate the designations of the connecting terminals and operating positions of the off-circuit tap changer. Not only electrical connections, but also actual locations of the terminals of the off-circuit tap changer (for example see fig.5) are given in the circuit diagram.

Denomination of the operating positions is identical with contact connections. The highest actual number of turns of the transformer winding is connected in the operating position “1”. Different designation is possible but as a special design. The contact designation used in overall dimensions drawings comply with the standards. The designation of the operating position of the drive mechanism is always identical to the position designated for off-circuit tap changer.

Series Number of poles 1, 2, 3, 4, 6

Rated current A

Rated voltage kV

Basic circuit diagram

TECHNICAL DATA Page.10 /17

4 2

16 15 0 ME

12 11 0 MD

06 02 0 Y/D

06 02 0 SP

V

2 1 W1

N

06 05 0 MD

U V

7 12

6 14

Fig.4

1U

N

N

16 15 0 MD

27 29

33 31

151712

W N

14 11

9 10

13 12

3 7

12 11 0 Y

12 11 0 ME

06 05 0 ME

3 3

06 05 0 Y

18 1414

4 5

9 10

8 7

4 5

9 10

16 15 0 Y

16 11 13

13 12

8 7

4 5

TECHNICAL DATA Page.11 /17 b

3 10

111−125−6 11−12 15−6

06050 P(ME)

Fig.5 − EXAMPLES OF CONNECTION DIAGRAM

DESIGNATION OF POSITIONS

CONNECTIONS

ADGUSTMENT POSITION

DIFERENT VOLTAGES

OPERATING POSITIONS

06050 P(ME)conection

PBVE

U ( V,W ) a b a6 b

10−124−6

4−7 10−13

9−143−8

3−7 9−13

10−124−6

4−7 10−13

9−143−8

3−7 9−13 a

06050Y

DIFFERENT VOLTAGES

ADJUSTMENT POSITION

conection

PBVK

DESIGNATION OF POSITIONS

CONNECTIONS

OPERATING POSITIONS

U (V,W)

N

06050ME

OPERATING POSITIONS

CONNECTIONS

ADJUSTMENT POSITION

DIFFERENT VOLTAGES

DESIGNATION OF POSITIONS

06050Y

5−6 1

PBVK

06050MEconnection

U ( V,W )

23−7

4−7

4−6

3−8

5−6

4−6

4−7

3−8

3−7

06050 MD

PBVE

ADGUSTMENT POSITION

conection

CONNECTIONS

DESIGNATION OF POSITIONS

OPERATING POSITIONS

DIFERENT VOLTAGES

U ( V,W ) a b

TECHNICAL DATA Page.12 /17

4. CHARACTERISTICS

4.1 Rated current

The rated through – current is the highest operating current for off-circuit tap changer, guaranteed by the manufacturer. The current carrying paths are designed for the rated through – current.

4.2 Temporary overload

The operating current can be temporary increased (see IEC publ. 354).

4.3 Short – circuit current

The short circuit current for the off-circuit tap changer is bigger than required by IEC 60214 – 1:2003.

The permissible thermal short – circuit current for a test period exceeding 3 sec. can be approximately determined as follows:

I th = I th(3) . (3/T)½ - T(s)

4.4 Contact life

In general, contact life of an off-circuit tap changer considerably exceeds the transformer life.

4.5 Temperature range.

Off-circuit tap changer can be operating within an oil temperature range from: -40°C to +105°C.

4.6 Insulation

The insulation level of off-circuit tap changer is defined by a series of withstanding voltages and successful tests. Off-circuit tap changer is characterized by two types of insulation – insulation to the ground (according to table 1)-and internal insulation of the off-circuit tap changer (as per table 3 and 4).The voltage tests according to above shown tables are applied for each new product with well dried by given method insulation, while the product is immersed in transformer oil with temperature at approx. 20°C.

The insulation to the ground corresponds to all national and international standards.

The internal insulation is determined by minimum withstanding voltages of a successful number of consequent tests, depending on the type of off-circuit tap changer and different positions of the moving contacts. Fig. 6 shows the specific insulation distance of the transformer windings for the basic circuit diagrams of off-circuit tap changer.

For the proper choice of the off-circuit tap changer, voltages shown in table 3 &4 must be considered with the voltages, which appear during impulse withstand voltage test of the transformer. The most unfavorable working position of the off-circuit tap changer must be taken into consideration.

5. SPECIAL DESIGN

On the basis of drawings for the 3 series of the off-circuit tap changer given in applications versions even more versions can be manufactured with special order.

They can be as follows:

• number of poles

• number of operating positions

• bigger of 1000A rated current ( with parallel transformer windings )

• for the installation in transformer with “Bell” type tank

• others

TECHNICAL DATA Page.13 /17 b a b b b a a

Fig.6 − SPECIFIC DIELECTRIC STRESS b o b b b b b a a o

W b

U V

WU V

b

U a ao b

WV

a a o

N WU V U V W

TECHNICAL DATA Page.16 /17

6. INSTALLATION

Off-circuit tap changer is developed mainly for mounting on “Deep” type transformer tank. For “Bell” type transformer tank PBVK and PBVE with “Special design” is provided. The off-circuit tap changer must be installed according to operating instruction applied to each product. The drying and vacuum regimes correspond to those applied to the transformer.

7. DRIVE

Off-circuit tap changer can be coupled with the following type of drives:

7.1 Manual drive wheel on the drive – fulfilled at special order. (see C-04)

7.2 Manual drive type ZR 03 – it is mounted on the transformer tank wall – standard version ZR-

03/10; ZR-03/03.

7.3 Motor drive mechanism type MZ 4.1 – it is mounted on the transformer tank wall – fulfilled at special order – MZ-4.9/07

7.4 Driving shaft, cardan coupler and bevel gear N 505,175.2, 442.2, 157,202.

7.5 Arrangement of the horizontal shafts – N 396

7.6 Vertical shaft – N394, 395.

7.7 Vertical driving shafts with intermediate support–ZR-03/07; 577.

1. Disassemble horizontal protective pipe:

2. Disconnect horizontal shaft:

3. Rotate the Hand Drive Unit.

3.1. If Hand drive unit is rotating (changing taps), problem is in Worm Gear Box of the

NLTC.

Important: After rotating Hand Drive Unit to a certain tap, go back to Tap No 3 immediately before continuing all other activities!

3.2. Check Worm Gear Box as per rotating the shaft directly with wrench size 20 and lever with approximate length L~0.5m.

3.3. Try to perform ½ revolutions in both directions and let us know the result

3.4. Open the cover of Worm Gear Box (7 bolts M8) make some pictures and send it to us.

Important: After rotating Worm Gear Box to a certain tap, go back to Tap No 3 (normal position) immediately before continuing all other activities!

Normal position: arrow and two bolts in one line, tap position number fully visible on tap position indicator.

4. Be sure that Hand Drive Unit and Worm Gear Box are on Tap No 3 and connect horizontal shaft and protective pipe in opposite to p.1&2 sequence.

Please request the client to make as much pictures as possible.

Please let me know if you require some assistance during inspection or further information about this issue.

Attached should be pictures taken on 10/21/19 when we further tore down the tap changer to the worm gear box. Our conclusion is that the worm gear box or something else internal to the tap changer is bound not allowing for any movement from the output shaft of the worm gear box.

Tap changer on Unit 2 GSU (TL 1786 SN 20092436TLD007-001) stuck on position 3. Hyundai previously sent us the attached procedure to investigate if the problem is in the hand drive unit, bevel drive, worm gear drive, or the tap changer inside the tank. We disconnected the coupling as shown in the procedure and everything had freedom of movement from the hand drive unit up to and including the bevel gear drive. So the problem appears to be confined to either the worm gear drive or the tap changer inside the tank. We did notice condensation on the underside of the worm gear sight glass, and what appeared to possibly be rust. Pictures are attached. Please advise as to next steps. I advised our maintenance personnel to avoid exercising the tap changers on all GSU transformers, due to concerns that they could get stuck in another position. At this time all transformers are in position 3 and the possibility that we would ever need to change tap positions is remote.