These are used to house a combination of 19” modular chassis, protection relays, switches, auxiliary relays, terminals, wiring and trunking. Protective relays and devices have been developed over 100 years ago to provide “lastline”of defense for the electrical systems. They are intended to quickly identify a fault and isolate it so the balance of the system continue to run under normal conditions. Definite time delay means that the protection operate time dose not change or depend on the. presentation of protection and control relaying. Fundamental concepts and terminology will be taught using the electromechanical overcurrent relay as a foundation. The specification relates to the Onshore Compensation Compound (OCC) and Offshore Substation Platform (OSP).
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