Siemens SIMOTICS S-1FK2, Operating Instructions Manual

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then you must use additional residual current protective devices RCD (RCCB or MRCD),
type B.
● RCCB: Residual current circuit breaker
● MRCD: An MRCD comprises an RCM (differential current monitoring device), a measuring
current transducer and a circuit breaker with additional undervoltage release, listed in the
Technical data.
To prevent an RCD from unnecessarily tripping as a result of operational leakage currents,
the following preconditions must be fulfilled:
● The neutral point of the line supply is grounded.
● Use an RCCB type B with a response limit current of 300 mA. Connect the RCCB in series
with the overcurrent protective devices.
● Use a separate RCD for each converter.
● The motor cables are shorter than 50 m (164 ft) and shielded.
WARNING
Risk of electric shock and fire from a network with an excessively high impedance
Excessively low short-circuit currents can lead to the protective devices not tripping or tripping
too late, and so causing electric shock or a fire.
● In the case of a conductor-conductor or conductor-ground short-circuit, ensure that the
short-circuit current at the point where the inverter is connected to the line supply at least
meets the minimum requirements for the response of the protective device used.
● You must use an additional residual-current device (RCD) if a conductor-ground short
circuit does not reach the short-circuit current required for the protective device to respond.
The required short-circuit current can be too low, especially for TT systems.
WARNING
Risk of electric shock and fire from a network with an impedance that is too low.
Excessively high short-circuit currents can lead to the protective devices not being able to
interrupt these short-circuit currents and being destroyed, and so causing electric shock or a
fire.
● Ensure that the uninfluenced short-circuit current at the line terminal of the inverter does
not exceed the breaking capacity (SCCR or Icc) of the protective device used.
Installing
5.4 Connecting the converter and the motor
SINAMICS S210 servo drive system
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Operating Instructions, 12/2017, A5E41702836B AA