Vacuum – a logical progressionAdvantages of the VUCL on-load tap-changer

1ZSC000562-ABB en

The new generations tap-changer is based on vacuum technique. With this technique the arc occurs in a vacuum interrupter and not in oil as with the traditional method. This greatly reduces the need for maintenance and makes it possible to use environmental-friendly insulation fluids.

Latest addition to our vacuum family is called VUCL and is designed for transformers in the voltage range up to 765 kV. With VUCL we continue our successful construction philosophy that means low complexity with few components. It is common sense that fewer components give a more reliable product.

The benefits of using the vacuum tap-changer are: − Lower life cycle costs, less maintenance needs, and

increased time in operation because of a radical reduction in contact wear.

− Routine inspection takes place in a cleaner environment which reduces downtime.

− Reduced sensitivity to moisture in the insulating oil due to the absence of polluting by-products such as carbon.

− Switching characteristics of the tap-changer do not depend on the status of the insulating oil.

− Reliable due to redundant contact system. − Fully interchangeable with existing installations. − Possible to use alternative insulating fluids.

2 Vacuum – a logical progression | 1ZSC000562-ABB en

Technical dataVUCL is one in a series of tap-changers from ABB based on vacuum technology. Both the conventional UCL and the newly developed VUCL are based on the diverter switch principle. They can be used in transformers of up to approximately 600 MVA which covers the most frequent applications. Both models have identical housings and tap selectors. Only the diverter switch mechanism differs which means that the unit is completely interchangeable, thus no redesign of the transformer is necessary.

Technical data tableFor detailed information, see Technical guide 1ZSC000562-AAX.

Type of switching: L (linear), R (plus/minus), D (coarse/fine)

Number of phases: Three-phase and single-phase

Highest rated lightning impulse withstand voltage to earth and between phases:

1050 kV

Highest rated power frequency withstand voltage to earth and between phases:

460 kV

Highest lightning impulse withstand voltage across regulating winding:

550 kV (This figure decreases with a higher number of positions, see the Technical Guide).

Maximum rated step voltage: 4500 V

Maximum rated through current: 1000 A

Maximum short circuit current strength: 15 kA rms 3 s / 38 kA peak

Maximum number of positions: 22 for L, 35 for R, D

Overhaul intervals: 300 000 operations

Mounting: In-tank

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Tap selectors

Type Connection Max. rated through-current Max impulse test voltage across range

III N, B 1000 A 550 kV 2)

E, T 1000, 1800, 2400 A 550 kV 2)

2) Note that for certain positions, these values are lower. See section “Insulating levels” in the Technical Guide.

Diverter switches

Type Max. rated through-current

VUCG.L, B, E, T 700, 1000, 1300, 2600 1) A

1) Only available in E, T connection and requires a forced current splitting during opera-tions. Contact the supplier for more information.

0

2000

3000

1000

4000

4500

0 1000500

0

200000

300000

100000

400000

500000

600000

0 1000500

Rated phase step voltageThe maximum permitted step voltage is limited by the electrical strength and the switching capacity of the diverter switch. The rated phase step voltage is a function of the rated through current as shown in the diagrams below.

For arc furnace transformers, only up to 75 % of the given step voltages below are allowed. In case the current during electrode short circuits exceeds twice the rated through-current, please contact the supplier for advice.

Leakage inductance at coarse/fine regulationWhen operating from the ends of the fine or the coarse winding, a high leakage inductande might appear causing a phase shift between the switched current and the recovery voltage. The leakage inductance value has to be given when ordering a tap-changer so a proper dimensioning is possible.

The leakage inductance value can be given in our order data sheet or be calculated by us from active part dimensions and number of turns. For more information, see IEC 60214-2 or product information 5492 0031-100.

Contact lifeThe predicted contact life of the fixed and moving contact of the diverter switch, is shown as a function of the rated through-current in the diagram below.

VUCL.N,B,E,T

No

. of o

per

atio

ns

Rated through-current (A)

Ste

p v

olta

ge

(V)

Rated through-current (A)

VUCL.N,B,E,T

1ZS

C00

0562

-AB

B e

n

© C

opyr

ight

201

2 A

BB

. A

ll rig

hts

rese

rved

.

Contact us

ABB AB ComponentsSE-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