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© ABB Group May 27, 2014 | Slide 1

ABB Transformer Components Because reliability is everything Vacuum OLTC

Product presentation CPT tech – Jason Evershed, ABB Transformer Components, May 21st 2014

Overview

Principles of operation and types

Technologies Quality Assurance Advantages on site Conclusion - Advantages




ABB Vacuum On-Load Tap Changer Principles of Operation and Types

Introduction to voltage regulation

The purpose of the tap-changer is to change the turn ratio between windings in a transformer

Regulation range is typically up to ± 20 % of the line voltage in 9 to 35 steps

Operated 10 to 20 times a day in normal grid applications


Introduction to voltage regulation

Tap-changers can be located in the main transformer tank, or on the outside

In-tank types can be used up to the largest transformers and highest voltages

On-tank types can be used for lower voltages


1ZSC000717-AAT

Over 100 years of experience


1900 1930 1960 1990 year

Traditional technology

First ASEA patent on vacuum technology

Diverter switch tap-changers Principle of operation


Diverter switch: Switching device used in conjunction with a tap-selector to carry, make or break currents in circuits which have already been selected

Tap selector: Device designed to carry, but not make or break, current, used in conjunction with a diverter switch to select tap connections Change-over selector: Device designed to carry, but not to make or break, current, used in conjunction with the tap selector switch to enable its contacts and the connection taps to be used more than once when moving from one extreme position to the other

Tap-changer types Four main product families

On-tank and in-tank

BIL level up to 1050 kV

Through current up to 1600 A in star connected applications for resistive and up to 2500 A for reactance type.

Unsurpassed reference list in challenging applications, e.g. HVDC and Ultra High Voltage systems (800 kV AC and DC)


Type UZ Type (V)UC Type (V)UB Type VRLTC

© ABB 5/27/2014 | Slide 9

Tap-changer types Portfolio overview

Vacu

um P

ortfo

lio

Con

vent

iona

l Po

rtfo

lio

Sel

. C

Sel

. III/

F

Sel

. III/

F

Sel

. III/

F

Sel

. IV

/F

Product name UZF UZE UBB UCG short UCG UCG UCL UCD UCC

Max voltage¹ (kV) 145 145 72.5 245 245 245 245 245 245

Max BIL (kV) 650 650 350 1050 1050 1050 1050 1050 1050

Max Current (A)4 600 600 500 600 600 600 900 1000 1600

On-tank In-tank

Sel

ec. C

Sel

ec. I

II/F

Sele

c. II

I/F

VRLTC VUBB3 VUCG short VUCG VUCG VUCL2

72.5 72.5 245 245 245 245

150 380 1050 1050 1050 1050

1500 600 800 800 800 1300

On-tank In-tank

Reactance Resistive

5

¹ For D-connection. Y-connections is restricted by insulation of neutral point to earth

2 1000 A until Sel. F is available during 2013.

2500

Selector switch tap-changers Type VUBB

Rated through current in star and delta connections 600 A

Step voltage up to 1600 V

BIL levels up to 380 kV

Up to 19 tap positions


Diverter switch tap-changers Type VUCG

Rated through current in star connections up to 800 A




Diverter switch tap-changers Type VUCL

Rated through current in star connections up to 1000 A*




* Will be increased to 1300 A with tap-selector F, during 2013

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ABB Vacuum On-Load Tap Changer Technologies

Tap-changers types Two main technologies

Traditional technology, using arc quenching in oil

UZ, UB and UC

Vacuum technology, using arc quenching in separate interrupters

VUC and VUB


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Product philosophy

Longest lifetime by using high class material

Type tested beyond international standards

High reliability by using few parts and low complexity in design

Easiest maintenance by using open designs

Easy upgrading to vacuum technology in existing installation


Diverter switch tap-changers Tap-selectors

Three tap-selector types C, III, IV Long-life design based on self-cleaning, sliding contacts Type tested for 1,500,000 operations. Experience from the

field shows they can do double


Vacuum interrupter technology Vacuum Interrupter

Safety and Reliability

1

2

3

4

5

6

7

Moving contact Metal bellow

Ceramic insulator

Shield Moving contact Fixed contact

Vacuum interrupter technology Maximal reliability - an absolute requirement

Exceptionally tested

Redundancy in the electrical contact system

Rotating mechanical systems minimize wear

Mechanical synchronization of the vacuum bottles


Diverter switch tap-changers Common features

Extensive service experience Tens of thousands units in

service Unsurpassed reference list in

challenging applications (HVDC) Quick and easy maintenance

Unique, open design, No special tools needed Shaft outside diverter switch

housing Maintenance videos is several

languages Reliable

Few parts Simple and robust design Mechanical lifetime exceeds

1,000,000 operations Traditional and vacuum technology

Easy to upgrade in the field


On-load tap-changer fundamentals Quality assurance



Quality assurance Type tests, IEC 60214 and IEEE C57.131

1. Temperature rise of contacts

2. Switching tests Service duty test Breaking capacity test

3. Short-circuit current test

4. Transition impedance test

5. Mechanical tests

6. Dielectric tests


Quality assurance Routine tests, IEC 60214

1. Mechanical test

2. Switching sequence test

3. Auxiliary circuit insulation test

4. Pressure and vacuum test

5. Visual inspection

Vacuum tap-changers are subject to additional testing, these includes

1. Leakage testing of vacuum interrupters

2. High voltage conditioning of vacuum interrupters

3. Mechanical conditioning of the vacuum interrupters




ABB Vacuum On-Load Tap Changer Advantages on site

Vacuum technology Field upgrading

Plug and play solution for all UCG since 1977.

Upgrade from conventional to vacuum technology in less than one day

As easy as a normal overhaul


© ABB Month DD, YYYY | Slide 24

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Diverter switch tap-changers Maintenance

Inspection - made annually with transformer in service

Overhaul - transformer out of service and OLTC drained Time based and

operation based for tradition technology

Only operation based for vacuum technology




ABB Vacuum On-Load Tap Changer Conclusion

Vacuum technology Benefits

Less maintenance and lower life cycle costs

300 000 operations between maintenance

Radical reduction in contact wear

Reduced downtime and cleaner maintenance environment

Reduced sensitivity to moisture in the tap-changer oil

Switching characteristics is independent on status of the insulating oil

Qualified for use with bio-degradable fluids (VUCG)

Significantly improved breaking capacity in demanding applications; more efficient use in HVDC


Questions and Discussions


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