Service and maintenance
11.2 Troubleshooting
3VL molded-case circuit breakers
144 System Manual, 03/2009, 110 0110 - 02 DS 01
Circuit breaker status Causes of faults Corrective action
High humidity The circuit breakers must not be used in environments with high
humidity since this can cause dielectric and insulation problems. In
such environments, appropriate measures need to be taken, such as
placing the circuit breaker in an enclosure.
Corrosion The circuit breakers are not designed to be used in aggressive
environments.
In such environments, the circuit breaker should be installed in a
housing.
Mechanical and
electrical functions:
Function of the internal
accessories
Determine what type of internal accessories are installed. Remove the
circuit breaker cover and determine the type of accessories using the
circuit breaker order number. Then check for correct functioning.
• Undervoltage release:
Ensure the correct voltage is connected to the undervoltage release
since otherwise, the circuit breaker cannot be tripped.
• Shunt release:
Ensure the voltage is not applied to the shunt release since this can
also prevent the circuit breaker from tripping.
• Auxiliary and alarm switches:
The auxiliary and alarm switches do not have any effect on the
functioning of the circuit breaker.
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