Diligent Protector For Ac Applications

Diligent AC relays are available for Over Load (OL) Single Phasing (SP) Phase Reversal (PR) etc. The overload relays are available in 1ph and 3ph types. 1ph-relays are useful on single phase load and can also used as economical solution for 3 ph applications whenever load is balanced. These are classified depending on the response to the overload condition and the classification is as follows

Instantaneous (INS) type. In this relay changes the state as soon as overload occurs.

Time-Delayed (DLY) type. In this the relay changes the state only after elapse of present period from the time overload occurred & stayed.

Jam (JAM) type. In this the control relay does not respond to the overload condition for a preset time from switching on the load but after elapse of this time the relay responds immediately to any overload.

Instantaneous type is primarily made for AC loads other then motor such as: transformer heater etc. However it has been also used along with other logic to control motor.

Time-Delayed overload relay find wide use. The tie delay provided in the relay avoids nuisance tripping in response to transient overloads but switches off the load if overload persists beyond the specified time. Most of the loads in actual practice increase temporarily and the drive is usually designed to handle this type of overloads.

Jam type overload relay is quite unique and has made possible very reliable protection of loads such as Blower Fans Stirrer motors.