Relays are commonly used in motor applications to measure and monitor operating parameters such as temperature, current and voltages. This is required to save the motor or its connected equipment from fault or abnormal operating conditions.
Voltage monitoring devices provide under voltage protection as well as Over voltage protection. Also, it protects against voltage related issues like Phase loss, phase sequence and phase asymmetry, Neutral open, over frequency and under frequency.
Voltage monitoring devices are designed for single-phase systems as well as for 3 phase systems.
Undervoltage is the condition that occurs when the average voltage of a 3 phase system falls under the intended level. Electromechanical devices, which include 3 phase motors, are designed to operate at specific voltage levels, but if they are working at low voltage levels, these systems will demand higher currents. Undervoltage conditions drastically reduce the life of electromechanical equipment. Whereas over-voltage protection is a power supply related feature which cuts off the supply when voltage exceeds the preset level of voltage. This may be caused due to various reasons like a sudden interruption of heavy loads, lightning impulses, switching impulses etc. This also damages the insulation, which protects the system. Though all the overvoltages do not stress