By Sean Silvey, product application specialist, Fluke
The electrical power issues that most often affect industrial plants include voltage sags and swells, harmonics, transients, and voltage and current unbalance.
In a balanced three-phase system, the phase voltages should be equal or very close to equal. Unbalance or imbalance is a measurement of the inequality of the phase voltages. Voltage imbalance is the measure of voltage differences between the phases of a three-phase system. It degrades the performance and shortens the life of three-phase motors.
The impact of the transients on motors can be severe. Motor winding insulation can break down, which can then lead to costly early motor failure and unplanned downtime.
Testing for Transient Voltage in Motors
Transient voltages — temporary unwanted spikes or blips of voltage in an electrical circuit — can come from any number of sources either inside or outside of an industrial plant.
Adjacent loads turning on or off, power-factor correction capacitor banks or even distant weather can generate transient voltages on distribution systems. These transients, which vary in amplitude and frequency, can erode or cause insulation breakdown in motor windings.