The usual focus in this column is what those squiggly waveforms are called and what causes them. Sometimes the focus is even what gets rid of them. In a recent meeting, a customer said, “I don’t care what they are or what caused them; I just want to know the equipment in my facility cares about them.” That’s really the bottom line for the customer: “If it doesn’t cause a problem with equipment in my facility, what do I care?”
According to one of the classic definitions, power quality is “a variation in the voltage, current or frequency that results in a misoperation of equipment.” So, even the definition concurs.
Using the infamous Table 4.2 from IEEE Std 1159 Recommended Practice on Monitoring Electric Power Quality (the most accepted source of what is used to name those power quality phenomena), let’s try to answer that customer’s question in general terms. We have to stay with generalities, since equipment susceptibility is specific to the actual manufacturer, make, model, age, maintenance history, environmental conditions, etc.
Also note that, in general, the equipment affected in the shorter duration power quality phenomena also would be affected in the longer duration phenomena of the same type, so it isn’t repeated in the subsequent rows.
In most categories of power quality phenomena, the longer the duration, the more likely the problem goes from a misoperation to equipment damage and sometimes complete failure. But even the shorter durations can begin to take a toll on the life expectancy of the equipment. Repetitive transients can chip away at a semiconductor layer or the insulating layer in an electrolytic capacitor with no outside evidence of pending doom until it finally fails catastrophically. The key is to understand what might be affected, what problems you are having in your facility and with which particular equipment, and what the quality of the electrical supply is at each of these affected pieces of equipment.
Of course, in today’s litigious society, we conclude with the disclaimer that results may very. This is not meant to indicate any particular type of equipment, equipment manufacturer or electric supplier is better, worse or at fault.
BINGHAM, a contributing editor for power quality, can be reached at 732.287.3680.