Description; Basic Structure Of The Withdrawable Circuit-Breaker; Circuit-Breaker Structure Of The Circuit-Breaker - ABB VM1 Installation And Service Instructions Manual

6.

Description

6.1. Basic structure of the withdrawable
circuit-breaker (Fig.10a)
The withdrawable truck (9), consists of a steel sheet structure
with wheels (3), on which the circuit-breaker with the relative
auxiliary components, the isolating contacts (10) for electrical
connection with the switchgear and the multi-pole secondary
connector (1) for connection of the circuit-breaker auxiliary
circuits are installed.
After having been racked into the switchgear and hooked up,
the withdrawable circuit-breaker can take up the following
positions: racked-out, isolated for test (with connector
inserted) and racked-in. The racked-in circuit-breaker is
automatically earthed by means of the truck wheels.
The magnetic actuator of the circuit-breaker and the
relative controls and indicators, are accessible from the
front. Withdrawable circuit-breakers of the same type and
characteristics are interchangeable.
However, the code of the connector prevents incorrect
combinations between the circuit-breaker and switchgear.
1
8
6
7
5
1. Secondary plug connector
1.1. Breaker frame
1.2. Front Plate
1.3. Slot for handling, both sides
2. "Ready" indicator
3. CLOSE push- button
4. OPEN push-button
fig. 10a
18
6.2. Circuit-breaker structure of the
circuit-breaker (Fig.10b)
The encapsulated poles are installed on the rear flat section of
the circuit-breaker frame (1.1. Fig. 10a). The live parts of the
circuit-breaker poles are enclosed in cast resin and protected
from impacts and other external influences.
With the circuit-breaker closed the current path for each pole
leads from the upper circuit-breaker terminal (1) to the fixed
contact (2a) in the vacuum interrupter (2), then via the moving
contact (2b) and the flexible connector (5) to the lower circuit-
breaker terminal (4).
The change of contact state is delivered by means of the
insulated link rod (7) with internal contact force springs (6).
5. Mechanical operating cycle counter
6. Mechanical CLOSE/OPEN indicator
7. Rating plate
8. Socket for emergency manual operation
9. Truck
10. Primary isolating contacts
11. Wheels
1.1
1.3
1.2
10
2
3
4
11
9