ABNORMAL VOLTAGE SUPPLY CAN DAMAGE EQUIPMENT
by Lance Adkins
Recently, Farmers' Electric Cooperative's consumers served from the Ranchvale Substation, west of Clovis, experienced an unusual outage situation. While this particular situation is rare, it is possible for a similar condition to occur at any electric utility, and knowing how to respond can save considerable wear-and-tear on your electrically powered equipment.
On Friday, June 15 at approximately 6:45 pm our answering service began receiving reports of low-voltage, or "brownout" conditions. Due to the wide area of customers affected, service crews went directly to the substation. Upon inspection they discovered one of three substation fuses (69,000 volt) was blown. They also observed the smoking remains of a Bull Snake hanging from a lightning arrestor on top of the substations' main power transformer. Servicemen opened both distribution circuit breakers to interrupt service to all customers served from the station, removed the snake and inspected the transformer for damage, re-fused the transformer, and energized the distribution circuit breakers restoring service to all consumers.
Many of the customers served from the station experienced an outage of approximately eighteen minutes, between the time the circuit breakers were opened and re-closed following removal of the snake and re-fusing of the station. However, there were a number of individual customers, including all customers receiving three-phase service who experienced low voltage conditions from the time the snake shorted across the lightning arrestor, and crews arrived, spotted the trouble, and opened the distribution circuit breakers.
A few customers have called to report damaged equipment, and ask if the Cooperative maintained insurance to cover their equipment loss. In addition, they wanted to learn how to prevent equipment damage if a similar situation happens again.
While all utilities carry insurance to cover certain situations, most will not cover consumers for losses when the utility is not directly responsible. As an example, if the loss were due to utility personnel incorrectly connecting lines, insurance carriers would likely consider claims for reimbursement, generally at a depreciated rate depending on the age of the damaged equipment. As a snake with a poor sense of direction caused this incident, the Cooperative's insurance carrier would not cover any equipment losses.
One key to preventing damage to your equipment is to limit the amount of time equipment is exposed to an abnormal variation in voltage. There are basically three conditions that will adversely affect electrically powered equipment; low voltage (brownout), high voltage, and repeated blinking. Any of these conditions can be localized, affecting only the service to your home, or more widespread, affecting service to customers on a particular line or substation. In any situation, if you experience irregularities with your electric service, report the situation to your utility immediately, and limit your equipment's exposure by unplugging electronic equipment and appliances or by turning home circuit breakers off. Items you might not think about, but are vulnerable, are refrigerated air-conditioning and your home's water well.
Low voltage is particularly hard on motor driven equipment, causing motors to run hot. Generally, motors have overload or over-current protection that automatically resets once the motor has cooled, or a particular device may have a manual reset button. If your home was experiencing a low-voltage condition, you would notice dim lights throughout your home.
If lights are dim in part of your home, and very bright in another part of your home, the cause is likely to be a broken neutral connection. Again, it is very important that you report this condition to utility personnel immediately and take steps to reduce your equipment's exposure to the condition by unplugging them. A faulty neutral connection will allow the voltage to "swing" from 0 to as much as 240 volts, and is particularly hard on sensitive electronic equipment, and appliances rated for 115 volts. Also, surge suppression devices you may have on computers are likely to fail under this condition, as they are not designed for sustained high voltage conditions. I have seen surge suppression devices melt under these conditions and could cause a fire hazard.
Blinking lights can occur in both good weather and bad. Generally, blinking lights are caused when something comes in contact with a power-line and falls away. Trees blowing in the wind, lightning strike, birds, and my least favorite, lines bumping together in high wind or with ice on them. Occasional blinks are expected, and several blinks over the course of a thunderstorm are generally nothing to worry about. Report repetitive blinking conditions to your utility, as this could indicate a more serious problem needing immediate attention.
It's difficult to try and discuss the many possibilities that could cause a problem with your electric service. Again, the key to preventing damage to your equipment is to report the condition to your utility immediately, and take action to limit the time equipment is exposed to the abnormal condition. Generally, if utility employees are able to determine that the problem is within your homes' electric wiring, they will ask that you contact a qualified, licensed electrician to perform repairs on your electrical wiring. Utility employees are trained in the construction and maintenance of the equipment necessary to deliver power to your meter, but, are not trained or licensed by the State of New Mexico to perform work beyond the utility service attachment.
Anytime you experience trouble with your electric service, please do not hesitate to call your utility. Utility servicemen are on call 24 hours each day, 365 days each year to serve you.
Lance Adkins is the General Manager of Farmers' Electric Cooperative in Clovis, New Mexico, providing electrical service to approximately 10,500 meters in New Mexico.
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