Simmons Consultants LLC

Specializing in Electrical Power System Studies


Electrical Engineering Studies

Simmons Consultants provides electrical engineering studies for the commercial and industrial market including short circuit analysis, motor starting, protective device coordination, protective device settings, and more.

We have the latest CAD software and Power Systems modeling software available. We can provide electronic copies of your projects upon request.

Short Circuit Analysis Purpose

The purpose of the short circuit analysis is to calculate the maximum probable fault currents at each bus in the distribution system. These calculations are then utilized to select or confirm the adequacy of the electrical component withstand these levels and safely interrupt these currents when necessary.  Short circuit calculations are made in general accordance with the American National Standards Institute (ANSI) C37~0lO, C37.5, and C37.l and IEEE standard 141, also known as the IEEE Red Book.


Protective Device Coordination Purpose

The purpose of the protective device coordination study is to select protective device settings which adequately protect the electrical system and also provide the optimal selectivity when clearing a fault.  False and nuisance trips should also be avoided.  Ideally, only the device closest to a fault operates to protect the system, so the remaining electrical system remains in operation.  The coordination selections are made in general accordance with the American National Standards Institute (ANSI) C37~0lO, C37.5, and C37.l and IEEE standard 141, also known as the IEEE Red Book


Basis of Arc Flash Methodology

The Arc Flash Study report follows the guidelines and procedures outlined in the NFPA 70E-2004 and IEEE 1584-2002.  Both methods are utilized to calculate the available incident energy.

Arc Flash Studies estimate incident energy exposure from potential arc sources.  To understand the purpose of an Arc Flash Study, it is important to understand the difference between a traditional fault and an arcing fault.  A bolted 3-phase, phase to phase, or phase to ground fault creates high current that flows through the network and the current is contained within the network.  Traditional fault studies are used to select equipment that can withstand and interrupt these short circuit currents.  Arcing faults occur when the current passes through vapor between two conducting materials.  These high-temperature arcs can cause fatal burns even when standing several feet from the arc.  The electrical arcs also shower droplets of molten material in the surrounding area, causing further hazard.  The arcing fault current is smaller than a traditional bolted fault current because the vapor acts as impedance between the conducting materials.  The Arc Flash Study, herein referred to as Arc Flash, follows the NFPA 70E 2004 and IEEE 1584 2002 methods for determining the arc-flash hazard distance and the incident energy that workers may be exposed to when working on or near electrical equipment.  Electrical arc burns account for a large percentage of electrical injuries.  An arc flash study combines short circuit calculations, empirical equations and protective device operating times to estimate incident energy and protective clothing requirements at typical working distances.


Fax or e-mail us your project drawings and materials list so that we can give you a detailed proposal.

We are very competitive and can provide quick turn around with all of the information provided in advance.


Simmons Consultants LLC
West Chester, PA 19380-1899
(610) 344-7667 phone/fax


Copyright 1999-2006, Simmons Consultants LLC

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