Steps of performing short circuit analysis
- Create an online account if you don't already have one, and log onto the page where you can add components one by one to build up a radial electrical distribution system. The components can be a power source, transformers, bus ducts, cables, motors and generators, or "special" components whereby the user can define his own X and R values for a non-standard device
- Build a one line diagram of distribution system
- Pre-assign each basic component within the industrial electrical distribution system a single short circuit MVA factor (SC MVA) based on the impedance it adds to the system, and X/R ratio
- Perform transformation of delta connected components of power distribution system to wye connection before the MVA method implemented in the calculator can be applied
- Develop a hierarchical tree in terms of database records. Loads not contributing to system's short circuit current (lighting, heating) are assigned a SC MVA value of 0. Unloaded transformers should also be terminated with the SC MVA = 0 node - this allows to calculate short circuits on the unloaded transformer secondary.
- Now, as you have all the required data on hand, login and program in your power distribution system. When finished, click Display button to calculate symmetrical 3 phase bolted fault short circuit MVA from the data compiled in steps 1 to 3. Divide total SC MVA values by 1.73 * kVLL to get short circuit values in kA
By performing short circuit MVA analysis for positive, negative and zero sequences, unsymmetrical fault (Phase to ground, Phase to phase) currents can be resolved.