S

4^46

Optional

Fig. 27-5 Line Diagram Illustrating Typical Protective Relays Used on a Medium-Voltage Generator. Source: Zenith Controls

Circuit Breakers

A circuit breaker is defined by NEMA Standards as a "device designed to open and close a circuit by non-automatic means and to open the circuit automatically on a pre-determined overcurrent when properly applied within its rating". Circuit breakers are switches that open in response to a prolonged overload or short-circuit current. The contacts are mechanically closed against the action of a heavy spring and held closed by a latch. Circuit breakers can be manually or automatically opened (tripped) by external signals, typically from some type of protective relay.

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Guide to Alternative Fuels

Your Alternative Fuel Solution for Saving Money, Reducing Oil Dependency, and Helping the Planet. Ethanol is an alternative to gasoline. The use of ethanol has been demonstrated to reduce greenhouse emissions slightly as compared to gasoline. Through this ebook, you are going to learn what you will need to know why choosing an alternative fuel may benefit you and your future.

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