Service and maintenance
5.3 Maintenance following tripping of a molded case circuit breaker
3VA molded case circuit breakers with IEC certificate
Manual, 03/2019, A5E03603177010-03
537
Maintenance following tripping of a molded case circuit breaker
If a 3VA molded case circuit breaker trips on overcurrent (overload, short circuit) or residual
current (ground fault or via residual current device), the cause of the trip must be identified
and rectified before the molded case circuit breaker is switched on again.
In the case of 3VA1 molded case circuit breakers with thermal-magnetic trip units, the cause
of tripping can be determined by means of the SAS short circuit alarm switch. With 3VA2
molded case circuit breakers, the cause of tripping can be output via the EFB300 external
function box. With electronic trip units 5-series and 8-series ETUs, the cause of tripping can
be indicated on the LCD and optionally transferred via communication modules.
An inspection as described in chapter Regular maintenance (Page 535) should be carried
out every time the molded case circuit breaker is tripped by the trip unit. In addition, all black
residues on the molded case circuit breaker must be removed as they might contain
conductive particles. The molded case circuit breaker should then be switched on and off
without load at least five times.
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