110 (4), ER (Electricity Regulations) 1994; any protective relay and device of an installation will need to be checked, tested and calibrated by a competent person at least once every two years, or at any time as directed by the Energy Commission. Many operators carry out secondary injection annually to ensure relays that protect circuits against overloads or faults operate appropriately. Q1: Do numerical relays require calibration? Numerical relays usually need validation of input signals (CT/PT accuracy) and firmware settings rather than traditional calibration. In most cases, the age and state of the relay, along with the manufacturer's recommendations, will be used to determine if more. If you've got relays in adverse conditions such as elevated humidity, dirt or temperature, then annual checks might be a good idea. This directive is intended to cover all protective relays, relay communication equipment, and disturbance monitoring equipment (collectively referred to as protection systems) associated with all 230kV and above transmission lines and associated facilities, all interconnection lines and facilities.
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