undervoltage relay

It is:

• to protect your Motors from Heavy Current draw-ins.
• to protect UPS's from on.off.on.off.--chattering
• to avoid causing fire at some unknown location in the system -where sparking/arcing is going on- resulting in low volage.

Idea is -Stop and Inspect-maybe one reclosure will clear the fault-maybe will persist-and a prolonged outage will be needed

The undervoltage relay is used to trip the ACB when the power fails. If under voltage relay is not used then the breaker will still remain ON and power supply will resume to downstream feeder as soon as power supply resume from incoming breaker. If you want the power should resume with out operation of the ACB then undervoltage relay can be eliminated. Undervoltage relays are used when the system is designed to remain off after resumption of power and to be switched on only by switch board attendant( operator). This system is designed only when the switch room is manned.

In protective systems and relays under voltage relays are used to cut off relays / breakers when incoming supply voltage is absent / less than preset value. This is required since voltage less than pre set value can damage the equipments.