VM1-T
- VACUUM CIRCUIT BREAKER
6
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3. Function
3.1 Function of the circuit breaker
operating mechanism
3.1.1 Magnetic actuator
(Figure 9/11)
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 magnetically 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 9/10 to 9/11)
The opening and closing processes can be remote
controlled by applying a voltage to input -MC (ON)
and -MO1 (OFF) (see 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 arrangement 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. 3 s)
it is also suitable for multi-shot reclosing.
3.1.4 Circuit breaker controller
All the conditions for control of the opening and
closing commands to the magnetic actuator are
defined in a fixedprogrammed logic module:
•
Supply voltage must be applied to the AC/DC
converter.
•
The storage capacitors must be sufficiently
charged for the next switching operation:
Switch position:
Storage capacitor energy for:
OFF
ON and OFF
ON
OFF
•
The moving contacts in the circuit breaker poles
must be in a defined ON or OFF limit position.
•
The closing coil can only be activated when the
breaker is OFF.
•
The opening coil can only be activated when the
breaker is ON.
•
Closing is disabled when an opening command is
simultaneously active.
•
Activation of the closing coil can be disabled by an
external blocking signal.
•
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.
•
Deactivation of the opening or closing coil takes
place when the relevant limit position has been
reached.
•
Input -MU “opening command” (undervoltage
release) and input -RL1 “closing lock-out”
(undervoltage release) must be energized for the
circuit breaker to be closed.
•
In the as-delivered condition of devices for
stationarymounted installation (without wiring),
these inputs are therefore provided with a voltage
of 80 V by an internal circuit as soon as the storage
capacitor is charged.
•
If these undervoltage releases are used to monitor
a voltage, the voltage to be monitored is to be
applied to these inputs.
•
If the voltage at undervoltage release -RL1 fails,
closing is blocked.
•
If the voltage at undervoltage release -MU fails,
the breaker opens.
•
Undervoltage release -MU (Figures 10/7 and 10/8).
Summary of Contents for VM1-T
Page 43: ...MEDIUM VOLTAGE PRODUCTS 43 ...
