Monitoring relays are an inexpensive solution for monitoring important electrical and physical system parameters. EMD monitoring relays can be used to monitor overvoltage, undervoltage, overcurrent, undercurrent, phase failure, phase sequence, phase asymmetry, power factor, active power, motor winding temperature, and fill levels. The current relay detects and monitors sinusoidal alternating currents in the frequency range from 45 to 65 Hz.