Coordination Study

Fuse and circuit breakers are extensively used in electrical systems to protect electrical equipment such cables, transformers, motors, and other components. A short circuit is frequently the result of a failure within these equipment’s. It would be preferable if the short circuit only affected the part of the system where the breakdown occurred, this could be achieved by properly coordinating breaker or fuses in a manner that the device closest to the fault acts before other upstream devices to clear the fault to minimize the impact. 

Protective devices are selected and modified in a well-coordinated system to reduce the impact of equipment failures within the system. In Coordination study analysis the characteristic curves of fuses and breakers are compared against each other on a log-log plot. Once on the log-log plot these breakers adjustable settings are adjusted to achieve proper coordination like the one shown in the image.

Most electrical power distribution systems are not designed with the coordination of protective devices in mind. Even though a distribution system is designed to have the fewest losses and the smallest initial cost, the protective devices may not be properly coordinated. As a result, equipment failures inside the system can quickly cause the entire plant to shut down. Many times, the loss of a single motor or branch circuit within a building has resulted in the facility’s whole operation being shut down.

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