Phase relays keep track of phase sequence, voltage balance, and phase loss. Using vector analysis and voltage comparison techniques, they are able to detect single-phasing and reverse phase sequence, enabling efficient operation while preventing motor damage. The latest models include modern digital phase relays, providing remote monitoring through RS485 communication as well as trip delay configuration options from 0.1 to 30 seconds. With surge suppression circuitry, these phase relays are protected against voltage transients up to 6 kV while complying with IEC 61000-4-5 electromagnetic compatibility standards. Their applications include but are not limited to ensuring reliable power supply and preventing expensive downtime in HVAC systems, industrial motor control stations, and pump stations.