ABB VM1-T Manual page 5

M E D I U M V O LTA G E P R O D U C T S
2.2 Structure of the breaker poles
(Figures 9/6, 9/7 and 9/11)
The poles in column design are mounted on the
bracketshaped rear part of mechanism enclosure 1.
The live parts of the breaker poles are enclosed in
cast resin and protected from impacts and other
external influences.
With the breaker closed, the current path leads from
the upper breaker terminal 25 to the fixed contact
24.2 in the vacuum interrupter 24, then via the
moving contact 24.1 and the flexible connector 21 to
the lower breaker terminal 22.
The switching motions are effected by means of the
insulated link rod 19 with internal contact force
springs 20.
2.3 Basic structure of the circuit
breaker on withdrawable part
(Figures 9/5 to 9/9 and 9/21)
The withdrawable part, which can be moved
manually or by a motor if fitted, consists of a steel
sheet structure on which the circuit breaker with its
ancillary components is mounted.
Insulated contact arms 34 with the spring-loaded
contact systems 34.1 are fitted to the circuit breaker
poles. These create the electrical connection to the
panel when the withdrawable part is inserted into
the service position.
A multi-pole control wiring plug connector 36.1
connects the signalling, protection and control
wiring between the panel and the withdrawable
part.
The withdrawable assembly and the circuit breaker
are connected via a multi-pole control wiring plug
connector 37.
As soon as the withdrawable part 31 has been slid
into the panel and its base frame has engaged in the
test/disconnected position, it is positively
connected to the panel. At the same time, it is
earthed by its travel rollers in their rails. The
magnetic actuator mechanism of the circuit breaker,
including its controls and indicators, is accessible at
the front of the withdrawable part.
Withdrawable parts of the same version are
interchangable. With the same dimensions but
different circuit breaker equipment, coding of the
control wiring plug prevents impermissible
combinations of withdrawable parts and panels (see
figure 9/14).
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