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Contact service life of main contacts
The characteristic curves show the contact service life
of contactors when switching resistive and inductive
three-phase loads (AC-1/AC-3) as a function of
breaking current and rated operational voltage. This
requires operating mechanisms that switch at
random, i.e. not synchronized with the phase angle of
the supply system.
The rated operational current I
utilization category AC-4 (breaking of 6 times the
rated operational current) is specified for a contact
service life of at least 200,000 operating cycles.
If a shorter contact service life is sufficient, the rated
operational current I
/AC-4 can be increased.
e
In the case of mixed operation, i.e. if normal switching
operation (breaking of rated operational current in
accordance with utilization category AC-3) is mixed
with occasional inching (breaking of the multiple rated
operational current in accordance with utilization
category AC-4), the service life of the contacts can be
calculated approximately using the following formula:
Legend for formula:
X: Contact service life for mixed operation in
•
operating cycles
A: Contact service life for normal operation (I
•
in operating cycles
B: Contact service life for inching (I
•
I
) in operating cycles
e
C: Proportion of inching operations as a
•
percentage of all operations
SIRIUS - SIRIUS 3RT Contactors/Contactor assemblies
Manual, 09/2017, A5E03656507120A/RS-AE/006
in accordance with
e
= I
)
a
e
= multiple of
a
6.16 Contact service life of auxiliary and main contacts
Size S00
Configuration
167
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