How do you know if your electrical distribution system components will work when called upon to interrupt an electrical fault or short-circuit? The answer is that you probably don’t know for sure. If unusually high currents exceed the capability of protective devices (fuses, circuit breakers, etc.) in the power system, a short-circuit can cause the devices to explode like a bomb. In order to identify these hazards before they occur is to perform a short circuit/protection coordination study on your electrical system.
Analyzing the Currents
A short-circuit study is an analysis of an electrical system that determines the magnitude of the currents that flow during an electrical fault. Comparing these calculated values against the equipment ratings is the first step to ensuring that the electrical system is safely protected. Once the expected short-circuit currents are known, a protection coordination study is performed to determine the optimum characteristics, ratings and settings of the power system protective devices
An electrical power system is designed so that if a short-circuit occurs, a protective device (such as a fuse or circuit breaker) will operate to “open the circuit” and prevent the continued flow of electrical energy to the faulted area. To minimize interruption of electrical service to other areas of the power system, the system is also designed so that the protective device closest to the short-circuit operates first to “clear the fault.”