Structure And Function; Withdrawable Part; Structure On The Breaker Poles; Structure Of The Breaker - ABB VD4 Product Manual

Structure and function

4
4.1 Basic structure of the circuit-breaker on
withdrawable breaker assembly
(Figures 4/1 to 4/3 and 7/1)
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 6 with the spring-loaded
contact systems 7 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 8
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 8.3.
As soon as the withdrawable part has been slid
into the panel and its base frame has engaged in
the test/disconnected position, it is positively con-
nected to the panel. At the same time, it is earthed
by its travel rollers in their rails. The stored-energy
spring 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 dif-
ferent circuit-breaker equipment, coding of the
control wiring
combinations of withdrawable parts and panels.
4.2 Structure of the breaker poles
(Figures 4/2, 4/5 and 4/6)
The poles in column design are mounted on the
bracket-shaped rear part of mechanism enclosure 9.1.
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 21 to the fixed
contact 20.2 in the vacuum interrupter 20, then via
the moving contact 20.3 and flexible connector 23
(or via multi-contact strips, depending on rated
current) to the lower breaker terminal 22.
The switching motions are effected by means of
the insulated link rod 26 with internal contact force
springs 25.
4.3 Structure of the breaker operating mechanism
(Figures 4/4, 4/6 and 4/7)
The operating mechanism is of the stored-energy
spring type. The necessary operating energy is
stored ready for activation by charging the spring
energy storage mechanism.
32
plug prevents impermissible
The stored-energy spring mechanism essentially
consists of drum 33 containing the spiral spring,
the charging system, the latching and operating
mechanism and the linkages which transmit the
force to the breaker poles. In addition, there are
supplementary components such as the charging
motor, releases, auxiliary switches and the controls
and instruments located on the front of the
mechanism enclosure 9.1.
The operating mechanism is fundamentally suitable
for auto-reclosing and, due to the short charging
times, also for multi-shot auto-reclosing.
In the basic version of the circuit-breaker, the
spring energy storage mechanism is charged
manually. The operating mechanism can optionally
be fitted with a charging motor.
There is one rating plate with the main data of the
switch equipment on front plate 9.2, and another at
the lower front right in mechanism enclosure 9.1.
The basic version of the stored-energy spring
mechanism is fitted with the following auxiliary
equipment:
• Shunt release OFF -Y2
• Five-pole auxiliary switch -S4 for
annunciation purposes
• Auxiliary switch -S7 for fault annunciation
• Mechanical ON push-button 11
• Mechanical OFF push-button 12
• Mechanical position indicator 13
• Charging condition indicator 18 for the
spring energy storage mechanism
• Mechanical operating cycle counter 14.
The following additional equipment can be installed:
• Blocking magnet -Y1 with auxiliary switch -S2
• Shunt release ON -Y3
• Second shunt release OFF -Y9
• Indirect overcurrent release -Y7
• Undervoltage release -Y4
• Five-pole auxiliary switches -S3 and -S5
• Charging motor -M0
• Five-pole auxiliary switch -S1 to switch the
charging motor.

4.3.1 Releases, blocking magnet and auxiliary switches

(Figures 2/15, 4/4, 4/7 and 8/1 to 8/3)
• The releases and the blocking magnet are
mounted at the top left on the spring operating
mechanism.
• The allocation of the auxiliary switches can be
seen in the wiring diagram of figure 2/15.