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Why Do You Need A Short Circuit & Coordination Study?

To avoid this!

A Short Circuit and Coordination Study (SC&C) is one of the most important steps you may ever take to protect either yours or your client's personnel and electrical distribution system. When an electrical fault exceeds a protective device interrupting rating, consequences can be devastating including injury, damaged electrical equipment, and costly downtime.

In a Short Circuit Study, faults are assumed at different points on the line side of various devices that will be interrupting the power system. This determines if a device can interrupt current available at the time of a fault. Often, the source side of the interrupting device is an electrical bus in a piece of switchgear. Forces are created when current flows through bus bars and varies depdendent on phase location. During a fault, current magnitude is radically greater than normal current flow, and the force between the bus bars is increased by the square of current increase (16x the normal force if the fault current is 4x normal). Short Circuit Studies yield information necessary to determine if breakers & fuses are capable of interrupting faults and determining whether or not switchgear bus sections are adequately supported to withstand forces generated by fault currents.

A Coordination Study looks at protective devices from a slightly different angle to

determine how to set protective devices in order to minimize the outage area. Selectivity is determined so a fault is interrupted only within its affected circuit, thereby, minimizing power disruption.

Each electrical system will have unique characteristics. As a facility grows or shrinks, the power needs and equipment are added or removed. Utilities also change out their transformers, re-route lines, and adjust their delivery of their power to you. Those changes alter an electrical system’s overall impedance, which in turn affects the protection requirements needed. There are two ways of knowing that your protective system needs adjustment: via the recommendations of a thorough study, or when your protective devices fail to interrupt a fault, resulting in a catastrophic explosion. Don’t wait for the latter to occur, get a study done today for peace of mind tomorrow.

We also recommend both a Load Study (system adequacy & proper protective device sizing/setting) and an Arc-Flash Hazard Study (analyzes arc-flash hazards to establish safe distances around electrical equipment and appropriate Personal Protection Equipment). Arc-flash data labels are attached to equipment enabling a facility manager to comply with NFPA/IEEE guidelines enforced by OSHA inspectors.

Our Professional Engineers can help with the above Engineering Studies and other Engineering Services!

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