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.

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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