Appendix B—Troubleshooting and Diagnostics
Power Xpert C445 Global Motor Management Relay
MN042003EN—January 2019
www.eaton.com
219
Table 84. Load Protection Fault Definitions
Phase Rotation (phase-reversal)
Improper wiring, leading to
phases being connected to the
motor improperly.
A miswired motor. Inadvertent
phase-reversal by the utility.
Phase-reversal can cause unwanted
directional rotation of a motor. In the
event that the load attached to the
motor can only be driven in one
direction, the result could be significant
mechanical failure
and/or injury to an operator.
Configurable phase protection, allowing the user to
define the phase sequencing intended for that
application. If no phase sequence is required, the
user has the ability to disable this feature.
Frequency Variance
When line frequency
is inconsistent.
Malfunctioning alternator speed
regulator, or poor line quality
caused by an overload of a supply
powered by individual sources.
Variations in frequency can cause
increases in losses, decreasing the
efficiency of the motor. In addition, this
can result in interference with
synchronous devices.
Advanced monitoring capabilities allow the user to
monitor frequency in real time. Users can also
optionally set an alarm or trip threshold for
frequency variations from 70–110%.
Definition
Source
Result
Power Xpert Protection
Under Current or Low Power
Average rms current provided to
the motor falls below normal
operating conditions.
Under current is usually associated
with a portion of the user’s load
disappearing. Examples of this
would be a broken belt, a dry-pump
(low suction head) or a dead-headed
centrifugal pump.
If under current goes undetected, a
mechanical failure can and has
occurred. In the case of a pump, running
a pump dry or running a pump in a
dead-headed condition can cause
excessive heating, damaging expensive
seals and breaking down desired fluid
properties.
Power Xpert has two protection settings to detect
this: under current and low power. Low power is a
more consistent way of ensuring detection as power
is linear with motor load, where as current is not.
An unloaded motor may draw 50% of its rated
current, but the power draw will be less than 10%
of rated power due to a low power factor.
High Power
The motor load is drawing more
power than it should at normal
operating conditions.
This is typical of batch processing
applications where several
ingredients flow into a mixer. When
a substance’s consistency changes
and viscosity increases from what is
expected, the motor may use more
power to blend the mixture.
Out-of-tolerance conditions can be
detected using the High Power and
Low Power settings.
If a high-power fault goes undetected,
the result may be a batch of material
that does not meet specification.
Monitors the three-phase real power. If the real
power value is estimated above the set threshold
for the set length of time, a fault is detected and the
overload will trip the starter. Additionally, power
can be monitored in real-time.
Table 83. Motor Protection Fault Definitions, continued
Definition
Source
Result
Power Xpert Protection
