Chapter 10—C445 Ground Fault Monitoring and Protection
210
Power Xpert C445 Global Motor Management Relay
MN042003EN—January 2019
www.eaton.com
The first time a GFM module is connected into a C445
system;
●
The C445 system will automatically configure the ground
current protection for
Fault Indication Only
and configure
output relay Q3 for “
Ground Current Fault
”.
●
The C445B… base module will auto-detect when a GFM
module is present in a C445 system and enable the
zero-sequence CT over the residual ground fault method
(default). The residual ground fault method cannot be
selected if the C445 system has recognized the GFM.
●
The auto configuration will occur only when the GFM is
connected into the C445 system for the very first time.
●
The auto configuration will not reoccur when a GFM has
already been detected, but a new or different GFM is
installed into the C445 system.
●
The auto configuration of output relay Q3 will only occur if
the current setting is the default.
The C445 system with a GFM installed will fault trip within
50ms + debounce setting value in the event that the CT is
exposed to a current in excess of 2X GFM range maximum
value.
The C445 system may be configured as a standalone system
whereas only ground fault monitoring and indication is
enabled. In such a configuration, a C445B… base module is
coupled to a GFM connected to the appropriate sized CT to
transmit monitoring information via a network. A C445M…
measurement module and/or a C445UM user interface
module may be added to provide local indication, control, and
protection.
The GFM also monitors the health of the CT and provides CT
status information to the C445B… base module. Status
information includes;
●
CT ok
●
CT secondary open
●
CT secondary shorted
●
CT calibration missing
The CT status information can be configured for No Action,
Fault Trip, or Fault Warning actions to the C445 System.
Note:
Output Q3 on the Base Control Module will
automatically be set to “21 Trip Reason - Ground
Current Fault” when a Ground Fault Module is
connected. This is the default. This can be changed
using the
in
Control software, the User Interface, or
the Web Pages. This parameter can be found under
the Operation Mode category, Advanced Settings.
Pulse Detection Protection
A pulse detection algorithm in the C445 works in conjunction
with Low Voltage High Resistance Ground Fault Pulsing
Systems. The pulse detection feature monitors the
calculated residual ground current and signals when a pulse
train is detected in the reading.
The C445B…base module monitors the residual ground
current reading and will signal a pulse is active when it
detects 4 similar pulses at least 80% of the programmed
pulse amplitude.
The C445 will respond to pulse rates between 3 to 100
pulses per minute.
The pulse detection feature may be configured to produce a
Fault trip, Fault No Trip, or Warning (default) reaction to a
detected pulse waveform.
Pulse Detection amplitude is user settable between 0.03A –
10.00A.
The C445 Pulse Detection feature aids in troubleshooting the
system by providing additional pulse information in addition
to upstream pulse detection equipment. If pulse detection
equipment upstream indicates that a pulse signal is present,
but the S445 system does not, then the ground fault lies
between the C445 measurement module and the upstream
equipment. If both the upstream equipment and the S445
System indicates a pulse signal is detected, then the ground
fault lies between the C445M… measurement module and
the load (motor).
