ABB V-Contact VSC 12, Installation And Service Instructions Manual

6

Fig. A
Magnetic circuit in the closed position.

Fig. B
Magnetic circuit with opening coil sup-
plied.

Fig. C
Magnetic circuit in the open position.

1. Description

The medium voltage V-Contact VSC contactors

are pieces of apparatus suitable for operating

in alternating current and are normally used to

control users requiring a high number of hourly

operations.

The basic contactors consist of:

• moulded polyester resin monobloc contain-

ing the vacuum interrupters

• bistable electromagnet drive

• multi-voltage feeder

• auxiliary contacts

• mechanical status indicator (open/closed).

Apart from what is specified for the fixed

contactors, the withdrawable contactors also

consist of:

• fuseholders preset for DIN or BS fuses (ac-

cording to the customer’s requirements)

• automatic opening device for intervention of

even a single fuse

• truck

• lock which prevents closing during the rack-

ing-in/out operation.

The V-Contact VSC contactor introduces the

drive with permanent magnets - already widely

used, experimented and appreciated in medium

voltage circuit-breakers - into the worldwide

panorama of medium voltage contactors.

The experience acquired by ABB in the field of

medium voltage circuit-breakers fitted with

drives with “MABS” permanent magnets, has

made it possible to develop an optimised ver-

sion of the actuator (Bistable MAC drive) for

medium voltage contactors.

The drive is operated by means of an electronic

feeder which, with just three versions, can cover

all the power supply voltage values required by

the major international Standards.

1.1. “MAC” magnetic drive

Based on the experience gained in the field of

circuit-breakers with magnetic drive, ABB has

implemented this technology in the field of

contactors.

The magnetic drive adapts perfectly to this type

of apparatus thanks to its precise and linear

travel.

This means that a simple and direct axial trans-

mission of the movement to the moving con-

tacts of the vacuum interrupter can be realised,

with both electrical and mechanical benefits.

The drive, which is of bistable type, is fitted with

an opening and a closing coil.

The two coils - individually energised - allow

the drive core to be moved from one of the two

stable positions to the other.

The drive shaft is solid with an iron core which

is immersed and held in position in a field gen-

erated by two permanent magnets (fig. A).

Energising the coil opposite to the magnetic

latching position (fig. A) of the core, the mag-

netic field (fig. B) is generated, which attracts

and moves the core into the opposite position

(fig. C).

Every opening and closing operation creates a

magnetic field concordant with the one gener-

ated by the permanent magnets, with the ad-

vantage, during service, of keeping the inten-

sity of the field itself constant as the number of

operations carried out increases.