Operation; Circuit-Breaker Function Magnetic Actuator; Circuit-Breaker Control - ABB VM1 Installation And Service Instructions Manual

7.

Operation

7.1. Circuit-breaker function
Magnetic actuator
The magnetic actuator used in the VM1/A/P circuit-breaker
generates the run required to operate the moving contacts of
the interrupters and integrates all the functions of a traditional
operating mechanism.
The magnetic 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 (13) motion is affected by activating the close
(11) and open (14) coil. In the limit positions the armature
is held in place magnetically by the field of two permanent
magnets (12). Changing of the switched position is performed
by exciting one of the two coils until the latching force of the
permanent magnets are exceeded.
The capacitors which allow circuit-breaker operation, for a
maximum time of two minutes, even in the case of a drop
in the auxiliary voltage, are provided in the control circuit.
In case of emergency, the circuit-breaker can in any case
be opened by means of a special crank handle which acts
directly on the moving armature of the drive (15).
Magnetic latching in end-of-run position.
fig. 12
28
(Refer to figure 10b)
Magnetic latching and action of the magnetic
field of a coil.

7.2. Circuit-breaker control

All the conditions for control of the magnetic actuator
mechanism are defined in a permanently programmed logic
module. These conditions are:
• Auxiliary voltage must be applied to the AC/DC converter.
• The storage capacitor must have sufficient charge for the
next switching operation.
• The moving contacts in the circuit-breaker poles must be in
a defined CLOSE or OPEN limit position.
• The closing coil can only be activated with the circuit-
breaker in the OPEN position.
The opening coil can only be activated with the circuit-breaker
in the CLOSE position.
• Closing is blocked when an opening command is
simultaneously active.
• Activation of the closing coil can be disabled by an external
blocking signal.
• The antipumping system ensures that, when a closing
command is applied and followed by an opening command,
only one CLOSE-OPEN switching operation is performed.
For the next closing operation, the active closing command
has to be cleared and must be issued again.
• Deactivation of the opening or closing coil takes place when
the relevant limit position has been reached.
Swich position: Storage capacitor energy for:
Open Close and open
Close Open
Moving armature in opposing position and
magnetic end-of-run latching.