Computer programs are required to calculate a realistic level of short-circuit currents. Short circuit current 240v/0.01536 15625 amp Now consider 20 feet of wire has resistance of about 0.005 (from an online wire impedance calc) To add them together one, one uses this Total impedance sqrt (0.0052 + 0.015362) 0.016153 In the excel file 20 feet has bolted short circuit current of 11,595 amp. Conservatively, it can be as high as 20–30 times the normal full-load current of the system.įor example, if a power system is designed to carry a full-load current of 2000 A, then the short-circuit capacity could be in the neighborhood of 20 * 2000 (40,000) A, or even 30 * 2000 (60,000) A. The calculation of the short-circuit capacity of a power system is very involved and complex. To avoid damage from excessive heat and the magnetic force created by a short circuit, all electrical circuits, and equipment connected to the system must have an interrupting rating or interrupting capacity, equal to or greater than the calculated short-circuit capacity of the system. Furthermore, there will most likely be the fire of combustible components within or in the vicinity. This situation is called a short circuit.ĭepending on the remaining resistance or impedance of the circuit, the short-circuit current could be up to 30 times as high as the normal current.Īt this abnormally high level, most equipment and wiring will be ruined by the excessive amount of heat generated. Transformer and Short Circuit Calculator.Electrical calculations (MS Excel SPREADSHEETS) Calculate the correction factor of the system factor. It is determined by the voltage and impedance of the supply system. 68, Use Shortcircuit calculations Spreadsheet following Brief Instructions.
If the resistance or impedance of the load is bypassed or shorted, then, according to Ohm’s law, an abnormally high current will flow through the circuit. Download: Available Fault Current Calculator Excel Spreadsheet The Available Fault Current, prospective short-circuit current (PSCC), or short-circuit making current is the highest electric current which can exist in a particular electrical system under short-circuit conditions.