To ensure adequate drive protection, the circuit breaker provided by the customer must fulfill
the following requirements:
● The total opening time of the circuit breaker – from the command to actually opening – must
● The drive monitors the TRIP coils (shunt releases) for wire breakage and failure of the
● The circuit breaker must be equipped with an undervoltage tripping function. The
● Avoid additional delay times when controlling the circuit breaker. All commands from the
● A feedback signal must be available for each of the circuit breaker states CLOSED and
● An additional, independently operating overcurrent protection for the circuit breaker must
● The circuit breaker is activated and enabled by the drive closed-loop controller. Under no
According to the EU machinery directive, machine manufacturers / plant operators must
conduct a risk assessment of their machine. Plant operators must conduct a risk assessment
of their plant. In particular, pay attention to Annex 1 "General Principles" of the EU machinery
SINAMICS SM120 6SL38715
Operating Instructions 07/2015
not be more than 80 ms. It is not permissible that the opening time, specified in the technical
documentation of the circuit breaker manufacturer, exceeds 80 ms. The drive monitors the
total opening time.
control voltage in the switchgear installation.
undervoltage trip unit (low-voltage coil) is controlled via the tripping circuit in which the
"undervoltage trip unit" of the drive must also be integrated. The auxiliary voltage from the
switchgear (this is a reliable supply) is used as the supply.
drive to the circuit breaker must act directly without intervention of coupling relays.
OPEN. The feedback signals must not be delayed. Do not use any coupling relays.
be provided on the plant side (transformer and cable protection).
circumstances should you close the circuit breaker by external mechanical or electrical
means. A mechanical interlock of the manual ON command at the circuit breaker prevents
destruction of the drive as a result of an uncoordinated switch-on operation.
2.7 Residual risks