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Power Quality Investigations

Power Quality

Is, roughly defined, the ability of an electrical system to support loads without the introduction of variations in the source that negatively affect the loads or power system.

If a system was capable of providing a perfectly regulated, continuous, sinusoidal voltage to an electrical load under all conditions, the power quality of that system might be considered perfect. However, in the real world, this is not the case. Voltages vary over the course of the day. Faults on the system result in momentary deep reductions in voltage. The switching of capacitor banks and some types of faults can result in harmful overvoltages. Poor wiring practices within a facility may compromise the grounding integrity. All of these can result in mis-operation, damage, or nuisance operation of equipment.

The investigation of a power quality problem must go beyond the ability to connect a meter and compile reams of data into a report with little analysis or understanding of the root problem. ELECT, P.C.’s experienced staff will investigate your power quality problem with an understanding of the factors that are and are not relevant, and how changes in the system or remedial equipment will affect the problem. ELECT, P.C.’s diagnostic process will minimizing metering and on-site disruptions, and arrive at a concise recommendation for the most practical and economic solution.

Transient Analysis

As a result of lightning strikes, system faults, switching events, and other anomalies, power systems are often subjected to voltages far greater than the system’s nominal, steady state voltages. While these overvoltages typically last for a only very brief period, usually far less than a millisecond, they can result in equipment misoperation and expensive equipment damage or accelerated aging. For this reason, transient surge suppressors and lightning arrestors are almost always located at critical locations in a power system, and where sensitive equipment is located. These devices, when properly applied, are very effective in limiting the maximum voltage on a system and protecting equipment.

However, if a system is not properly protected, protective devices have failed, or transient events are not severe enough to be clamped, a well-designed system can still experience problems. Because transients are often unpredictable, the metering and diagnosis of the exact problem is often very difficult.

ELECT, P.C. can identify and measure power system transients and model these using software, if necessary, in order to diagnose or solve transient-related power systems problems.

Harmonic Analysis Studies

The proliferation of electronic and other “nonlinear” loads has resulted in the introduction of harmonic currents and voltages into typical power systems. While often harmless, these higher frequency components can sometimes create problems with equipment capacity, power factor correction capacitors, and occasionally, equipment mis-operation. ELECT, P.C. can characterize a system with respect to the sources and effects of power system harmonics and recommend remedial measures if required.

Motor Starting Studies

Motor Starting StudiesStarting large motors can cause severe disturbances to electrical power systems due to the large current drawn by motors when starting. ELECT, P.C. performs motor starting studies to determine the ability of an electric power system, either the utility or local generation, to start a given motor without collapsing the system voltage or resulting in unacceptable starting torque. IEEE Standard 399 recommends motor starting studies be performed if a given motor horsepower exceeds 30% of the base transformer kVA rating of the supplying transformer or if the horsepower exceeds 10-15% of a generator intended to run the motor. These studies can identify the cause of observed problems or determine the performance of a proposed design or solution.