Relay Protection - How does Cold Load Pickup (CLP) function work

Why do we need Cold Load Pickup protection function

When a typical load has been without supply for a period of time (hours) it loses its diversity. When power is restored the load is higher than usual because all the heater, refrigerator or air conditioner thermostats have turned on. The longer the period without supply the greater the loss of diversity and the higher the load current when supply is restored.

Cold Load Pickup feature

The purpose of the Cold Load Pickup feature is to allow for this loss of diversity automatically and hold the load without tripping. It works by timing the loss of supply to the load and then raising the threshold current accordingly.