Electric Terms and Definitions ......

---

Power quality

Learn what affects your electricity

As we have moved more into the world of electronics over the past few years, there has been more concern about the quality of our electricity.

Before we had these new electronic devices, a small interruption in power or a surge in the power supply generally went unnoticed. That is no longer true. The smallest blip can cause a computer to lose data.

Now power quality has also improved substantially, but the new microprocessors in computers and other electronic equipment keep getting more and more sensitive.

With more and more SIEA customers acquiring this kind of sensitive electronic equipment, power quality is a concern for all of us.

Most members do not understand the power quality problem and may believe the utility is totally responsible for all the problems they experience. Actually, about 60 percent of these problems are generated within the home or business. Neighboring customers, natural phenomena and normal utility operations cause the other 40 percent of the problems.

The electrical systems we use in basic appliances are based on technology and equipment designed in the early 1900's. This equipment is not as sensitive to electrical interruptions as today's electronic equipment. That is why fluctuations in power supply rarely affect a refrigerator, freezer, washer and dryer. But electronic equipment, operated by microprocessors, is affected by interruptions of less than 1/60th of a second.

These chips are sensitive to interruptions, from natural phenomena (weather, animals, tree limbs, etc.), utility operations, neighbors, as well as from appliances and equipment, within the home or business.

The following definitions describe most of the poor quality conditions that can be experienced.

OUTAGE   - An outage is a complete loss of power caused by a short circuit in the customer's wiring or in the electrical utility system. Short circuits cause circuit breakers to trip open or fuses to blow.

SURGE   - Surges are temporary excess conditions in current, voltage, or both. These may be caused by lightning, power line switching, or customers turning heavy power equipment on or off.

UNDERVOLTAGE   - Undervoltage conditions result from poor wiring, overloaded circuits, or a deficiency in the utility system.

HARMONICS   - Harmonics are distortions in the power signal caused by equipment in the home or business. Alternating current electric power leaving the power plant is a pure 60 Hertz (cycles per second) sine wave. But its shape may be distorted at the point of use by power controllers such as variable speed drives and light dimmers. The result is a jagged voltage sine wave. This transient or continuous "noise" radiates through the wiring and is absorbed by other electrical devices.

VOLTAGE SAGS   - Voltage sags are momentary power dips that last for a few seconds or less. Like surges, sags may happen when large power devices start. For example, the initial start up of a refrigerator compressor may cause the light to dim if the household wiring is inadequate.

OVERVOLTAGE   - Overvoltage is any condition where the electric utility supply voltage exceeds accepted standards.

So there are many cause of poor power quality. Problems come not only from the electric utility, such as SIEA, but other sources. The may originate in your own home, from a neighbor, or from nature.

All of us have to work together to try to cure these problems as they occur. Diagnosing and eliminating the cause may cure some poor power quality problems. Others, such as lightning, are beyond control, so some sort of protection, such as lightning arrestors which are standard equipment on SIEA distribution lines, are required. Surge suppressors, power conditioners, or uninterruptible power sources may also be useful, depending on the electrical devices to be protected.

SIEA encourages consumers to consider some of these protection devices for sensitive equipment, like computers and VCR's. We must keep in mind that while electricity has become increasingly important in our lives and that we tend to take it for granted, there is a rick factor involved in using this commodity.

SIEA has equipment in its distribution system to protect the system and the customers from many power quality problems. Yet, due to some outside causes of these problems, no protection device is 100 percent foolproof.

However, SIEA feels that the more levels of protection that customers have, the better they will be at protecting their electronic equipment.

 

---