ABB VM1 Installation And Service Instructions Manual page 19

M E D I U M V O LTA G E P R O D U C T S
7.3.3. Interlock in the case where non-ABB
withdrawable trucks are used
The VM1 circuit breakers mounted on non-ABB
withdrawable trucks must be fitted with one or
two additional auxiliary contacts interlocked with
the mechanical interlocks. These contacts must
cut off the input voltage directed to the electric
closing lock.
Similarly to what takes place for the auxiliary
contacts on the ABB withdrawable truck,
additional electrical impulses cannot be received
after the first half-turn of the spindle (2) (fig. 10).
The electrical impulses can only be applied again
after the last half-turn. This guarantees that it is
impossible to close the circuit breaker when the
withdrawable truck is in an intermediate position.
It is therefore necessary to implement a
mechanical interlock to prevent movement of a
1
2
Fig. 11
closed circuit breaker. The slide locking device (1)
(fig. 11) on the circuit breaker (optional accessory
for fixed circuit breakers) can be used for this
purpose: if the VM1 circuit-breaker is closed, the
slide locking device is outside the base plate (2)
(fig. 11).
Figure 11 shows the pawl (3) on the ABB
withdrawable truck. If the circuit breaker is
closed, the pawl (3) cannot be turned
anticlockwise. This prevents movement of the
withdrawable truck and therefore movement of
the circuit breaker.
Note: any additional interlocks must not exert any force on the circuit
breaker drive.
If the interlocking mechanism extends beyond the base of the circuit
breaker housing, suitable measures must be taken to prevent the circuit
breaker from resting on the interlock, for example during transport.
3
19 19