Appendix B—Troubleshooting and Diagnostics218 Power Xpert C445 Global Motor Management Relay MN042003EN—January 2019 www.eaton.comAppendix B—Troubleshooting and DiagnosticsTable 83. Motor Protection Fault DefinitionsDefinition Source Result Power Xpert ProtectionThermal OverloadOverload is a condition in whichcurrent draw to a motor exceeds115% of the full load amperagerating over a period of time foran inductive motor.An increase in the load or torquethat is being driven by the motor.A low voltage supply to the motorwould cause the current to go highto maintain the power needed.A poor power factor would causeabove normal current draw.Increase in current draw. Current leadsto heat and insulation breakdown,which can cause system failure.Additionally, an increase in current canincrease power consumption and wastevaluable energy.Thermal trip behavior is defined by UL, CSA and IECstandards.Trip class is settable from 5–40 by 1Provides power factor monitoring and low voltageprotection features.JamJam is similar to thermaloverload in that it is a currentdraw on the motor above normaloperating conditions.Mechanical stall, interference, jamor seizure of the motor or motorload.The motor attempts to drive the load,which has more resistive force due tothe mechanical interference. In order todrive the load, the motor draws anabnormal amount of current, which canlead to insulation breakdown andsystem failure.Provides a configurable Jam setting that is activeduring “motor run state” to avoid nuisance trips.Trip Threshold 50–400% of FLA.Trip Delay 1–20 seconds.Ground FaultA line to ground fault. A current leakage path to ground. An undetected ground fault can burnthrough multiple insulation windings,ultimately leading to motor failure.Power Xpert has ground fault protection capabilitywith a sensitivity of 3 A or less up through 90 Aapplications using the built in three phase CTs andthe residual current method. That is, thethree-phase current signals should sum to zerounless a Ground Fault (GF) condition is present. Inthe case of a GF, Power Xpert can alarm, trip thestarter, or trip an alternative relay that can be usedto shunt trip a breaker or light up a warning light. GFcurrent can also be monitored in real-time throughthe advanced monitoring capabilities. Forapplications requiring higher ground fault sensitivityacross all FLA ranges, add the C445XG-MODExternal Ground Fault Module. Refer to Chapter 10for more information.Note: GF settable thresholds vary with motor FLA.See Table 26 Current Based Protections for eachminimum level.Imbalanced Phases (voltage and current)Uneven voltage or currentsbetween phases in athree-phase system.When a three-phase load ispowered with a poor quality line,the voltage per phase may beimbalanced.Imbalanced voltage causes largeimbalanced currents and as a result thiscan lead to motor stator windings beingoverloaded, causing excessive heating,reduced motor efficiency and reducedinsulation life.Provides two protection settings that address thisproblem. The user can choose to set currentimbalance thresholds or voltage imbalancethresholds, each of which can trip the starter.Additionally, both of these may be monitoredthrough Power Xpert’s advanced monitoringcapabilities, allowing the customer to notice inreal-time when and where a condition is present.Phase Loss—Current (single-phasing)One of the three-phase currentis not present.Multiple causes, loose wire,improper wiring, grounded phase,open fuse, and so on.Single-phasing can lead to unwantedmotor vibrations in addition to theresults of imbalanced phases as listedabove.Fixed protective setting that takes the starter offlineif a phase drops below 60% of the other twophases.
