ABB VM1, Manual, Page: 6 / 52

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VM1
- INSTRUCTION MANUAL BA 504/05 E
2.2 Structure of the breaker poles
(Figures 9/7, 9/9 and 9/12)
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 9/7 to 9/10, 9/17 and
9/22)
The withdrawable part, which can be moved
manually, 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, an optional
coding of the control wiring plug can prevent
impermissible combinations of withdrawable
parts and panels (see figure 9/15).
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2. Structure