Basic Structure Of The Circuit-Breaker On Withdrawable Part; Function; Function Of The Circuit-Breaker Operating Mechanism; Magnetic Actuator - ABB VM1 Instruction Manual

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 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 sys-
tems 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 con-
nected 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/discon-
nected 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, includ-
ing its controls and indicators, is accessible at the front of the
withdrawable part.
Withdrawable parts of the same version are interchang-
able. 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).
3

Function

3.1 Function of the circuit-breaker operating
mechanism
3.1.1

Magnetic actuator

(Figure 9/12)
The actuator is the heart of the circuit-breaker operating
mechanism. It combines the following integrated functions:
- latching in the limit positions,
- release,
- switching.
The actuator is a bistable permanent magnet system in which
the armature motion is effected by activating the ON or OFF
coil. In the limit positions, the armature is held in place mag-
netically by the field of two permanent magnets. Release of a
switching operation is effected by exciting one of the two coils
until the latching force of the permanent magnets is exceeded
temporarily.
3.1.2

Opening and closing procedure

(Figures 9/11 to 9/12)
The opening and closing processes can be remote controlled
by applying a voltage to input -MC (ON) and -MO1 (OFF) (see
8 VM1 Vacuum circuit-breaker | Instruction manual 504/05
also sections 10.1.1a and 6.2). The breaker can be operated
locally by pressing push-buttons 3 and 4.
In the closing process, the armature motion acts direct via lever
shaft 18 on the moving contact 24.1 until the contacts meet.
In the further motion sequence, the pretensioned spring arrange-
ment 20 is tensioned to 100 % and the necessary contact force
thus applied. The available overtravel is greater than the maximum
contact burn-off throughout the life of the vacuum interrupter.
3.1.3 Reclosing sequence
The operating mechanism is fundamentally prepared for
reclosing, and with the short recharging time of the storage
capacitor (max. 5 s) it is also suitable for multi-shot reclosing.
3.1.4

Circuit-breaker controller

The control module is available as a standard version and as
a full version.

3.1.4.1 Function of the standard version

All the conditions for control of the opening and closing com-
mands to the magnetic actuator are defined in a microprocessor:
- Supply voltage must be applied to the AC/DC converter.
- The storage capacitor must be sufficiently charged for the
next switching operation:
Switch position
OFF
ON
- The closing coil can only be activated when the breaker is
OFF.
- Closing is disabled when an opening command is simulta-
neously active.
- Deactivation of the opening or closing coil takes place when
the relevant limit position has been reached.
If the ON limit position is not reached within 70 ms during
a closing operation, an opening operation is immediately initi-
ated so as to ensure a defined switch position in all cases.
- The anti-pumping system ensures that only one ON-OFF
operation is performed when a closing command is active
and followed by an opening command. The active closing
command must be cancelled and reset for the next closing
operation.
- Activation of the closing coil (-RL1) can be blocked by an
external blocking signal.
- Input -RL1 "closing lock-out" (closed circuit shunt release)
must be energized for the circuit-breaker to be closed.
- In the as-delivered condition of devices for stationary-
mounted installation (without wiring), this input is therefore
provided with a voltage of 80 V by an internal circuit as
soon as the storage capacitor is charged.
- If this closed circuit shunt release -RL1 is used to monitor
an external voltage, the voltage to be monitored is to be
applied to this input.
Storage capacitor-energy for
ON and OFF
OFF