Free online assessment for arc hazards

A new free online tool calculates arc incident energy, flash protection boundary and risk category when work is to be performed on or near energised equipment.

A new free online calculator based on the IEEE1584 guide for performing arc-flash hazard calculations was developed as an easy to use yet comprehensive tool for calculating arc incident energy, flash protection boundary and risk category required by the NEC when work is to be performed on or near the energised equipment.

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, 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 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.

It 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.

The IEEE1584 empirically derived model was chosen for purpose of analysing arc flash faults due to the model ability to accurately account for variety of setup parameters, namely, open and box equipment configurations, grounding of all types and ungrounded, gap between conductors of 3 to 152mm, 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 IEEE1584 based arc flash calculations are provided.

Besides input data validation, the calculator comes accompanied with novel online short-circuit calculator which allows to quickly obtain accurate potential short circuit current at each bus in a radial electric power distribution system.

The IEEE1584 guide complements and generalises existing procedures suitable for one manufacturer protective devices only or limited to 600V systems and most typical set parameters only.

The calculator can be accessed via the ArcAd website.

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