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M E D I U M V O LTA G E P R O D U C T S
5.3. Interlocks/protection against
malfunction
A series of interlocks is provided to prevent
incorrect operations and/or malfunctions. The
interlocks are the following:
• the withdrawable truck can only be moved from the
test/isolated position to the service position (and
vice versa) if the circuit breaker is open (this means
that first of all the circuitbreaker must be opened).
• the circuit breaker can be closed if the withdrawable
truck is exactly in the defined test position or in the
service position (electric interlock).
• the circuit breaker can be opened manually in the
service or test position when it is not powered, but
it cannot be closed.
• the switchgear is provided with devices which only
allow connection and disconnection of the plug
connector (Secondary disconnects Fig. 4) (Fig. 7) in
the test/ isolation position.
Any detailed information regarding additional
interlocks, e.g. in connection with the earthing
switch operating mechanism, is given in the specific
order documentation.
Fig. 7a
Interlocks
The VM1/A/P circuit breaker contains a number of
interlocks. A description of each interlock follows as
encountered during racking of the circuit breaker
into the compartment.
DANGER
Modification to interlocks can result in
hazardous conditions to personnel and
equipment. Do not override, by pass or
adjust interlocks.
Modification to interlocks may result in serious
bodily injury or death.
Interference blocking: A mechanical plug
interference blocking in the circuit breaker
compartment prevents under rated circuit breakers
from being inserted into higher rated
compartments. The code plate rating includes
continuous current, interrupting current, close and
latch capability, and maximum voltage.
1
2
2
Fig. 7b
1
3
17 17
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