Short Circuit Analysis
“The objectives of electrical system protection and coordination are to prevent injury to personnel, to minimize damage to the system components and to limit the extent and duration of service interruption whenever equipment failure, human error or adverse natural events occur in any portion of the system.” -IEEE/ANSI std. 242-1986.
This study comprises of:
- Calculation of system fault current duties that can be compared with the first cycle momentary or close-and-latch ratings and interrupting ratings of circuit-interrupting devices, such as circuit breakers and fuses.
- Calculation of system fault current duties to compare with short-time or withstanding ratings of system components, such as busway, cables, transformers, reactors, disconnect switches, etc.
- The selecting and rating or settings of short-circuit protective devices, such as solid-state trip units, moulded case breakers, fuses and relays.
- Evaluation of short-circuit current flow and voltage levels in the overall system for short circuit in specific areas.
- Three phase, line-line, line-ground, line-out faults, etc.
- Symmetrical and asymmetrical components of the faults
- Momentary (transient) interrupting (subtransient 3-5 cycles), continuous 30 cycles and voltage sensitivity
- Motor and generator contributions
- One-line or tabular results
