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Why Does My Clock Radio Lose Time & Blink?

"April showers bring May flowers..." is a line from a poem that most of us learned in grade school. It brings back memories of pleasant spring mornings with occasional afternoon showers. But for all the freshness and beauty of spring, we must also contend with one of nature's most dramatic events - the fury of a thunderstorm.

The severe lightning that accompanies a springtime thunderstorm can sometimes wreak havoc on an electrical distribution system. With voltages exceeding several million volts and temperatures approaching 27,000 degrees Fahrenheit, lightning can destroy anything that lies in the electrical path that is forged between ground and sky.

Even though electrical facilities are insulated to withstand high magnitudes of voltage, they are sometimes no match for the awesome power unleashed by a lightning strike. The extreme heat generated by these high-level charges can explode trees by vaporizing their sap and can melt sand into shards of glass.

Each spring, we receive calls from concerned consumers saying that every time a thundershower occurs, their lights blink on and off and they have to reset all of their electronic clocks.

The answer to the problem of "tattletale" clocks is simple: buy one with a battery backup. These clocks do not require resetting when the lights blink, and also maintain accurate time during an extended outage.

The solution to the blinking lights is a little more complicated, and by the same token, much more interesting. Let's take a look.

CVEC installs various protective devices on its electrical system to take care of temporary or "transient" system disturbances. One of these devices is a lightning arrester. Every transformer is equipped with one. Also, they are placed at certain locations along the line and at every place where the line dead-ends. Lightning arresters are connected between the high-voltage conductor and the ground wire. By their physical makeup, they act as a high-voltage resistor, not allowing voltage or current to pass through during their at-rest, or static, state.

However, when lightning arresters sense a higher-than-normal voltage on the line, caused by lightning for example, they turn on and allow the voltage to flow through them to ground. Therefore, they work as a shunt, allowing the high voltage to go around the piece of equipment being protected. Usually, the arrester will turn itself off after the high voltage has passed through and returns to its normal characteristic of a resistor. Sometimes, however, the stresses generated by a lightning strike will be so great that the arrester will literally explode.

In either case, our second means of protection comes into play. During times of system disturbance when high magnitudes of voltage and current are present, line reclosers are used to de-energize the distribution circuit. If lightning causes the disturbance, then the recloser opens up long enough to allow the arrester to get the lightning off of the line. It immediately "recloses" to restore power. At this point, you notice the lights blinking. If a permanent fault, such as a tree on the line, causes the disturbance, then the recloser will turn itself on and off several times, trying to rid itself of the problem. If the fault remains after multiple blinks, then the recloser will turn itself off until the fault is removed. This step requires that a CVEC crew correct the problem, then re-energize the line.

Other types of protective devices safeguard our electric lines. However, lightning arresters and line reclosers do most of the work during an electrical storm.

We know that blinking lights can sometimes become a nuisance. But rest assured that our equipment is working hard to maintain continuous and reliable electrical service. Without the use of such protective devices, blinking lights could become extended outages.

Central Virginia Electric Cooperative
Corporate Headquarters: 800 Cooperative Way Arrington, VA 22922-3300	phone: (434) 263-8336 toll-free: (800) 367-2832 fax: (434) 263-8339	Mailing Address: P.O. Box 247 Lovingston, VA 22949