Appendix B—Troubleshooting and Diagnostics
218
Power Xpert C445 Global Motor Management Relay
MN042003EN—January 2019
www.eaton.com
Appendix B—Troubleshooting and Diagnostics
Table 83. Motor Protection Fault Definitions
Definition
Source
Result
Power Xpert Protection
Thermal Overload
Overload is a condition in which
current draw to a motor exceeds
115% of the full load amperage
rating over a period of time for
an inductive motor.
An increase in the load or torque
that is being driven by the motor.
A low voltage supply to the motor
would cause the current to go high
to maintain the power needed.
A poor power factor would cause
above normal current draw.
Increase in current draw. Current leads
to heat and insulation breakdown,
which can cause system failure.
Additionally, an increase in current can
increase power consumption and waste
valuable energy.
Thermal trip behavior is defined by UL, CSA and IEC
standards.
Trip class is settable from 5–40 by 1
Provides power factor monitoring and low voltage
protection features.
Jam
Jam is similar to thermal
overload in that it is a current
draw on the motor above normal
operating conditions.
Mechanical stall, interference, jam
or seizure of the motor or motor
load.
The motor attempts to drive the load,
which has more resistive force due to
the mechanical interference. In order to
drive the load, the motor draws an
abnormal amount of current, which can
lead to insulation breakdown and
system failure.
Provides a configurable Jam setting that is active
during “motor run state” to avoid nuisance trips.
Trip Threshold 50–400% of FLA.
Trip Delay 1–20 seconds.
Ground Fault
A line to ground fault.
A current leakage path to ground.
An undetected ground fault can burn
through multiple insulation windings,
ultimately leading to motor failure.
Power Xpert has ground fault protection capability
with a sensitivity of 3 A or less up through 90 A
applications using the built in three phase CTs and
the residual current method. That is, the
three-phase current signals should sum to zero
unless a Ground Fault (GF) condition is present. In
the case of a GF, Power Xpert can alarm, trip the
starter, or trip an alternative relay that can be used
to shunt trip a breaker or light up a warning light. GF
current can also be monitored in real-time through
the advanced monitoring capabilities. For
applications requiring higher ground fault sensitivity
across all FLA ranges, add the C445XG-MOD
External Ground Fault Module. Refer to
Chapter 10
for more information.
Note:
GF settable thresholds vary with motor FLA.
See
Table 26
Current Based Protections for each
minimum level.
Imbalanced Phases (voltage and current)
Uneven voltage or currents
between phases in a
three-phase system.
When a three-phase load is
powered with a poor quality line,
the voltage per phase may be
imbalanced.
Imbalanced voltage causes large
imbalanced currents and as a result this
can lead to motor stator windings being
overloaded, causing excessive heating,
reduced motor efficiency and reduced
insulation life.
Provides two protection settings that address this
problem. The user can choose to set current
imbalance thresholds or voltage imbalance
thresholds, each of which can trip the starter.
Additionally, both of these may be monitored
through Power Xpert’s advanced monitoring
capabilities, allowing the customer to notice in
real-time when and where a condition is present.
Phase Loss—Current (single-phasing)
One of the three-phase current
is not present.
Multiple causes, loose wire,
improper wiring, grounded phase,
open fuse, and so on.
Single-phasing can lead to unwanted
motor vibrations in addition to the
results of imbalanced phases as listed
above.
Fixed protective setting that takes the starter offline
if a phase drops below 60% of the other two
phases.
