Inspection and maintenance
5.7 Maintaining the main contacts
3WA1 air circuit breaker
Equipment Manual, 02/2023, 92310000002-06
405
Arc chute article numbers
Breaking capacity N and S
DC non-automatic circuit breaker, breaking capacity E
Breaking capacity S, M and H
DC non-automatic circuit breaker, breaking capacity D
DC non-automatic circuit breaker, breaking capacity E
Breaking capacity E and C
You can purchase the accessories in the Siemens Industry Mall
(http://www.siemens.com/product?3WA9111-0AS*).
5.7 Maintaining the main contacts
5.7.1 Introduction
The main contacts can be replaced as often as required until the circuit breaker has
reached its maximum mechanical service life including maintenance. As soon as the
circuit breaker has reached its maximum mechanical service life with maintenance, it
must be replaced.
The maximum mechanical service life of the circuit breaker depends on the total number
of operating cycles achieved. A distinction is made between electrical and mechanical
operating cycles.
• Electrical operating cycles:
Every switching operation (ON or OFF) of an air circuit breaker with current flow via
the main contacts up to the maximum rated current is considered an electrical
operating cycle. Due to the current flow, wear of the contacts is higher here than in
case of a purely mechanical operating cycle.
• Mechanical operating cycles:
Every switching operation (ON, OFF) of an air circuit breaker, with or without current
flow, is considered a mechanical operating cycle.
The electrical operating cycles are thus a subset of the mechanical operating cycles.
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