Configuration
4.3 Load feeders - protection against short circuit
SIRIUS 3RM1 motor starter
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Manual, 11/2013, A5E0345285095020A/RS-AB/002
4.3
Load feeders - protection against short circuit
4.3.1
Protection against short circuit
The short-circuit strength in combination with fuses is up to 100 kA at 400 V and with SIRIUS
3RV2 motor starter protectors up to 55 kA at 400 V. Type of coordination 1 is maintained
here.
DANGER
Hazardous Voltage at the Motor
Can Cause Death, Serious Injury, or Property Damage.
Health hazard from automatic hot restart.
The safety function must be checked after every tripping of the motor starter protector (also
in the case of overload).
After every short circuit in the case of short-circuit protection according to type of
coordination 1, a 3RM1 motor starter is defective.
Replace a 3RM1 motor starter including the terminals after a short circuit in the case of
short-circuit protection according to type of coordination 1.
With 3RM11/3RM13 Failsafe motor starters, you must check the safety function in addition
to replacing the unit.
With 3RM11/3RM13 Failsafe motor starters, also check the safety function after a short
circuit in the case of short-circuit protection according to type of coordination 2.
4.3.2
Configuration of load feeders
The 3RM1 motor starters can be combined with any short-circuit protection devices. Using
SIRIUS 3RV20 motor starter protectors offers a convenient solution for the configuration of
fuseless load feeders. However, combinations with fuses are also possible, mastering
particularly high short-circuit currents. Type of coordination 2 (see Glossary (Page 165)) can
also be achieved.
4.3.3
Configuration of a load feeder with 3RM1 motor starter in compliance with IEC
Short-circuit protection for load feeders in compliance with IEC can also be realized by motor
starter protectors or fuses. Depending on the design of the protection device, the two types
of coordination 1 or 2 can be achieved. The protection devices listed are the maximum
permissible versions and, as an alternative, protection devices of the same type with a lower
rated current can be used.
