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3RU11, 3RB10, and 3RB12 overload relays
SIRIUS System Manual
GWA 4NEB 430 0999-02b
4-13
4.2.3 Operation
Short-circuit protection
For short-circuit protection of starter combinations consisting of a contactor
and an overload relay, fuses or 3RV13 circuit breakers are required for
starter combinations.
Use with external cur-
rent transformers
If external current transformers are to be used to operate the 3RB12, the
following things should be taken into consideration. The 3RB12 with the cur-
rent setting range from 1.25 to 6.3 A must be selected.
The secondary current of the 1 A or 5 A current transformer becomes the
primary current of the 3RB12. In the case of 5 A current transformers, the
3RB12 can be set from 1.25 to 5 A (i.e. from 1/4 of to 1 times the trans-
former's rated current). In the case of 1 A current transformers, a signal
> 1.25 A must be generated by looping the line. If the line is looped five
times, a 5 A signal is generated for the 3RB12.
Environmental conditi-
ons
3RU11
The 3RU11 overload relays can be used without restrictions at ambient tem-
peratures of up to 60 °C. This is the result of new bimetals and continuous
temperature compensation (up to 70 °C with derating).
3RB10
A special coating on the PCB and the electronic components ensures reli-
able operation even in corrosive and tropical environmental conditions.
Auxiliary contact ele-
ments
The 3RU11 and 3RB10 overload relays are equipped with a normally closed
contact for switching off the contactor and a normally open contact for the
tripped signal.
The switching contacts have a high switching capacity so that they can
switch contactor coils directly. The overload relays are therefore suitable for
use with a PLC (17 V, 5 mA).
Coil and auxiliary
switch repetition termi-
nal
Frame size S00
In the case of direct mounting onto contactors, the auxiliary switch and coil
repeat terminals (A2) are passed through the 3RU1116 and 3RB1016 over-
load relays. This makes wiring much simpler.
Frame sizes S0 - S3
The contactors of these frame sizes are equipped with 4 coil connections. It
is therefore not necessary to pass through the auxiliary switch and coil ter-
minals (A2) of the contactor.
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