Sept. 25, 2008
-- The IEEE 1584 empirically derived model was chosen for the analyzing arc flash faults since the model is capable to accurately account for variety of setup parameters: open and box equipment configurations, grounding of all types and ungrounded, gap between conductors of 3 to 152 mm, bolted fault currents in the range of 700A to 106kA, system voltages in the range of 208V to 15kV, and working distances. Reference data listing most typical configurations and detailed procedure for IEEE 1584 based arc flash calculations has been included in the calculator.
The calculator takes equipment configuration, gap between electrodes, grounding type, short circuit fault current value and system voltage on input, and determines arcing fault current at potential point of fault. Next, the incident energy, flash protection boundary and level of personnel protective equipment are determined based on equipment configuration, arc duration and working distance.
For protective devices operating in the steep portion of their time-current curves, a small change in current causes a big change in operating time. Incident energy is linear with time, so arc current variation may have a big effect on incident energy. The IEEE 1584 solution is to make two arc current and energy calculations:
one using the calculated expected arc current and one using a reduced arc current that is 15% lower.
The calculator makes possible both calculations for each case considered. The IEEE 1584 procedure requires that an operating time be determined for both the expected arc current and the reduced arc current. Incident energy is calculated for both sets of arc currents and operating times and the larger incident energy is taken as the model result. This solution was developed by comparing the results of arc current calculations using the best available arc current equation with actual measured arc current in the test database. The calculator predicts arcing fault current for a given configuration and bolted fault short circuit current. It also predicts bolted fault current required to cause 15% reduction of the predicted arcing current for the given configuration.
Please visit ARCAD online at www.arcadvisor.com or contact us at firstname.lastname@example.org for more information.
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ARCAD helps facilities create safer working environments for individuals who service electrical systems by providing novel on-line and PC based software tools for short circuit and arc flash hazard analysis.