Siemens SIMOCODE pro - Monitoring Functions; Ground Fault Monitoring; Description of Functions of Ground-Fault Monitoring

Parameters
4.3 Monitoring functions
SIMOCODE pro - Parameterize
122 Operating Manual, 04/2017, A5E40507630002A/RS-AA/001
4.3
Monitoring functions
4.3.1
Ground fault monitoring
4.3.1.1
Description of functions of ground-fault monitoring
Residual current monitoring relays are used in industry to:
● Protect systems from damage caused by residual currents
● Prevent production losses caused by unplanned downtime
● Perform maintenance to meet all demands.
In particular, ground-fault monitoring is used in conjunction with 3UL23 residual current
transformers to monitor systems where environmental conditions increase the chance of
fault currents.
Internal ground-fault monitoring
SIMOCODE pro acquires and monitors all three phase currents. By evaluating the
summation current of the three current values, the motor feeder can be monitored for a
possible residual current or ground fault.
Internal ground-fault monitoring via current measuring modules or current / voltage
measuring modules is only possible for motors with a 3-phase connection in power systems
that are either grounded solidly or with low impedance.
NOTICE
Star-delta connection
Spurious tripping can occur if you use internal ground-fault monitoring for star-delta circuits.
During delta operation, the summation current is non-zero due to harmonics.