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6.16.3
3RT10 power contactors and 3RT12 vacuum contactors (sizes S6 to S12)
6.16.3.1
Mechanical endurance
The mechanical service life of contactors is a crucial criterion for their cost-effective use. This
is expressed as the number of operating cycles achieved without loading the current path.
While you cannot demand an excessively long service life from breakers that have to work
with relatively high contact loads, such as disconnectors and circuit breakers, without
impairing their cost effectiveness, contactors are available as specific switching devices for
extremely high numbers of switching operations and switching frequencies.
Mechanical service life of the 3RT1 contactors:
● Basic units, sizes S6 to S12: 10 million operating cycles
6.16.3.2
Electrical endurance
Electrical service life of main contacts
The service life of the contact pieces is as follows:
● In the case of rated operational current I
(breaking of 6 times the rated operating current): 200,000 operating cycles
● In the case of mixed operation, i.e. if normal switching operation (breaking of rated
operating current in accordance with utilization category AC-3) is mixed with occasional
inching (breaking of the multiple rated operating current in accordance with utilization
category AC-4): Operating cycles can be calculated approximately with the following
formula:
Characters in the equation:
● X: contact endurance for mixed operation in operating cycles
● A: Contact service life for normal operation (Ia = I
● B: Contact service life for inching (I
● C: Inching operations as a percentage of total switching operations
SIRIUS - SIRIUS 3RT Contactors/Contactor assemblies
Manual, 09/2017, A5E03656507120A/RS-AE/006
6.16 Contact service life of auxiliary and main contacts
in accordance with utilization category AC-4
e
) in operating cycles
e
= multiple of I
) in operating cycles
a
e
Configuration
175
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