Monitoring Functions
9.1 Earth Fault
SIMOCODE PRO V PN FDI
44
Programming and Operating Manual, 05/2020, A5E44499659002A/RS-AA/001
9.1.2
Internal earth-fault monitoring when using a current measuring module or a 2nd
generation current / voltage measuring module
Internal earth-fault monitoring via current measuring modules or current / voltage measuring
modules is only possible for motors with a 3-phase connection in networks that are either
grounded directly or with low impedance. You can activate internal ground-fault monitoring
by parameterization.
It covers two different operating conditions:
●
Normal stationary use case up to 2x rated motor current I
s
:
–
Residual currents greater than the value of the set trip / warning levels are detected.
–
Ground-fault monitoring fulfills the accuracy requirements of IEC 60947-1 Class II-B.
●
Temporary starting or overload operation greater than 2x rated motor current I
s
:
–
Responsiveness in the overload range of > 2x rated motor current is reduced to
reduce false tripping.
–
Residual currents of > 1/2 * I_trip level/I_s * I_max (of the effective motor current) are
detected.
NOTICE
False tripping in the case of internal ground-fault monitoring
False tripping can occur if you use internal earth-fault monitoring for star-delta circuits.
During delta operation, the residual current is non-zero due to harmonics.
Trip level activity, warning level
Unless deactivated, this function is always active, independent of whether the motor is
running or not (operating state "ON").
Here you can specify in which motor operating states the trip level / warning level will be
active:
●
Always (on): Trip level / warning level is always active, regardless of whether the motor is
running or at a standstill
●
If motor is running, except TPF (run): Trip level / warning level is only active when the
motor is running
●
If motor is running, except with TPF, with startup override (run+): Trip level / warning level
is only active when the motor is running and starting has been completed
