ABB V-Contact VSC Series Installation And Service Instructions Manual page 8

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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
Fig. A
Magnetic circuit in the closed position.
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.
Fig. B
Magnetic circuit with opening coil sup-
plied.
Fig. C
Magnetic circuit in the open position.