BENSHAW RediStart MX3 Series, User Manual

Page: 104 / 238

96
6 - PARAMETER DESCRIPTION
Residual Ground Fault Trip Level PFN 07
LCD Display
Range Off, 5 – 100 % FLA (Default Off)
Description The Residual Ground Fault Trip Level parameter sets a ground fault current trip or indicate level that can be
used to protect the system from a ground fault condition. The starter monitors the instantaneous sum of the
three line currents to detect the ground fault current.
Ground Fault Trip: The MX
3
will trip with a ground fault indication if:
- No other fault currently exists.
- Ground fault current is equal to or greater than the GF Trip Level for a time
period greater than the GF Trip Delay (PFN09).
Once the starter recognizes a ground fault condition, it shuts down the motor and declares a Fault 38 (Ground
Fault).
If a programmable relay (I/O 10-15) is set to "GROUND FAULT", the starter energizes the relay when the
condition exists.
A typical value for the ground fault current setting is 10% to 20% of the full load amps of the motor.
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NOTE: This type of protection is meant to provide machine ground fault protection only. It is not meant to
provide human ground fault protection.
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NOTE: The MX
3
residual ground fault protection function is meant to detect ground faults on solidly
grounded systems. Use on a high impedance or floating ground power system may impair the usefulness of
the MX
3
residual ground fault detection feature.
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NOTE: Due to uneven CT saturation effects and motor and power system variations, there may be small
values of residual ground fault currents measured by the MX
3
during normal operation.
See Also Ground Fault Trip Time (PFN09) on page 98.
Auto Reset parameter (PFN23) on page 102.
Controlled Fault Stop Enable parameter (PFN25) on page 103.
Relay Output Configuration parameters (I/O 10 - 15) on page 112.
PFN: Resid GF Lvl
07
Off
Alarm
Condition
Fault
Trip
% FLA
Ground Fault
Trip Time
PFN 09
Residual Gnd Fault
Level
PFN 07
Time