Power Quality 101

For one to understand and demystify power quality having electrical distortions such as over voltages, transient voltages and harmonics that are plaguing modern facilities, and the Power Factor, we present these brief descriptions of such disturbances polluting our modern electrical energy grid systems.

The term "transient" has been used to cover a wide spectrum of power disturbances such as surge, spike, RF (radio frequency) and harmonic activity. These disturbances are often known as "dirty power" or "power pollution". Disturbances in voltage (the magnitude of potential) relate specifically to voltage surges and spikes. Noise in electric current relates more to radio frequencies and harmonic activity. All aspects of power disturbances must be addressed to achieve true power quality.

The effect on motors is that (motors are moveable transformers), they are affected by the rise in current and frequency and generate eddy currents. The voltage effect on the motor is that this can punch through the magnetic winding and create a short circuit. The Canadian Electrical Association has calculated reductions in service life at 32.5 percent for single-phase machines, 18 percent for three-phase machines and five percent for transformers and universal machines.

Advances in digital logic technology have produced smaller and more sophisticated computers and electronic equipment. The new generation of micro circuitry is extremely dense. This dramatically increases its susceptibility to harmonics and high speed, high-energy over voltages.

The cumulative effect imposed upon contacts, coils and semi-conductors by numerous disruptive surges, including harmonics, cause efficiency losses on the motors, which in turn will substantially increase power consumption as the motor compensates to meet demand.

As pitting and corrosion occur, there is a rise in the operational temperature of the motor, which increases kilowatt usage and maintenance costs, as well as reduces the life expectancy of the motors and ballasts.