Inspection & Maintenance
4.3 Planning of inspection and maintenance
3WJ Air Circuit breakers
168 Operating Instructions, 12/2022, L1V30828903001-01
4.3 Planning of inspection and maintenance
4.3.1 Inspection interval
Malfunction due to insufficient inspection or maintenance
The circuit breaker may not function properly if inspection intervals are not adhered to or if
maintenance measures are not performed.
It is absolutely necessary to adhere to the prescribed inspection and maintenance intervals
and the instructions on repair and replacement in order to avoid personal injury and
The operator defines the inspection intervals within the following constraints based on the
operating conditions of the circuit breaker:
• At least once a year.
• After each short-circuit trip
• After five overload trips
4.3.2 Scope
Inspection
The inspection comprises:
• Visual inspection for:
– Pollution
– Damage
– Corrosion
• Check of available documentation and of rating/accessory label to ensure that they
correspond to the actual circuit breaker equipment.
• Testing of the mechanical function of the circuit breaker by closing and opening (a
minimum current load of 200 A is recommended in order to remove the corrosion on the
contact surfaces, thereby reducing power losses).
• Mechanical and electrical testing of the rack-in position indicators.
• Testing of auxiliary circuits and of cables to external current sensors for secure fitting of
auxiliary supply connectors and for correct connection.
• Testing of mechanical and electrical function of internal accessories.
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