Low voltage motors (defined as motors under 1000V) need different protection measures than their higher voltage cousins. Proper motor protection and monitoring in conjunction with a good maintenance schedule will extend the life of your motor and driven application significantly; as well as prevent unscheduled downtime and costly repairs due to easy to prevent failures. Below you will find our three tiers of recommendations for low voltage motor protection.
Good
- Electronic Overload Relay
- Includes monitoring of overload, loss of phase, phase unbalance, and ground faults.
- Short Circuit Protection
- Fuses or circuit breakers are permissible.
Better
- Programmable Motor Protector
- Includes programmable monitoring of voltage, amperage, kilowattage, etc. As well as a digital display, digital communications, trip class, recloser protection, and undercurrent monitoring.
- Short Circuit Protection
- Fuses or circuit breakers are permissible.
- Optional: Temperature Monitoring
- A thermostat or resistance temperature detection method is permissible.
Best
- Multifunction Protective Relay
- Includes programmable monitoring of motor waveforms, ground faults, rotor and stator temperature predictive algorithms, harmonic monitoring, resistance temperature detection, zero sequence, differential options, etc.
- Short Circuit Protection
- Fuses or circuit breakers are permissible.
- Resistance Temperature Detection
- Optional: Zero Sequence CT and Vibration and/or Shock Pulse Monitoring
This article is based off our EMC Webinar: Getting the Most out of Your Electric Motor
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Director of Motor Service
Josh has over 20 years of experience in electric motor repair, as well as welding and machining. He is also an expert mechanic. He is in charge of our motor service centers in all 5 EMC locations.