Protection Guide for Electrical Equipment
Who pays for equipment damage resulting from power failure - the member, the Cooperative, or the insurance company?
- Protect against quick restarts.
Momentary power interruption to a central air conditioner or heat pump can result in damage to the compressor. For $85 to $125, your dealer can install a time delay device that will keep the unit from restarting immediately when the power supply is momentarily interrupted. The device gives the compressor 3 to 5 minutes for its pressures to stabilize before allowing it to restart.
- Protect against low or high voltage.
Several products are available that provide protection. They often provide more than one function. A voltage-sensing relay is available that will shut the motor down when voltage falls below or rises above adjustable set points. Installation of this device and the time delay device mentioned above are good protective measures. A solid-state device can be installed on your equipment that protects against all 3 problems: high voltage, low voltage, and quick restarts. Often a device is installed as standard equipment on some new air conditioners and heat pumps that will only protect against low voltage and quick restarts, but not high voltage. Check with your equipment dealer to see what kind of protection you have or need
- Protect against phase failure, phase reversal, or frequency failure.
Devices are available to protect from loss of three-phase compressors and large motors where one or more phases are dead or where the rotation of the equipment is reversed due to two of the three supply phases being reversed.
Some devices provide protection from unacceptable frequency levels as well. Protective devices in this category are generally more expensive and are found more commonly on large commercial motors and compressors. The over-load heaters provided with motor starting equipment may not protect the motor from single-phasing. If the additional protective devices described here are omitted, load conditions exist where a motor is vulnerable to single-phasing.
- Protection against lightning.
Secondary lightning arresters are commonly installed on large commercial air conditioning systems. For residential systems, placement of a secondary lightning arrester at the weatherhead, meter base, or service entrance panel will provide some lightning protection for air conditioners and other household circuits. See the Lightning Protection section on the following page for additional information.
- Protection for televisions and other electronics.
A device that is designed to protect televisions and VCRs against voltage spikes can be purchased for under $50. It senses the momentary surge of voltage caused by lightning hitting the distribution system near your home. The television plugs into this adapter and then into the wall outlet. Once this device operates to prevent a spike from damaging the television, it must be replaced. It is neither effective against a direct lightning strike nor will it protect against sustained high or low voltage caused by a damaged distribution transformer.
- Protection for appliances
There are solid state protective devices designed for window air conditioners, refrigerators, and freezers. They could be used on other appliances as well, but the cost is prohibitive for small appliances. They serve the same three functions: protection against quick restarts, low voltage, and high voltage. They plug in as an adapter, also. Additional protection for appliances can be obtained through proper grounding and the use of secondary lightning arresters.
- Ground properly
Often the grounding of the home (or other structure) is inadequate to protect against lightning. Grounding conductors should be fastened to ground rods with HEAVY DUTY GROUNDING CLAMPS that are suitable for this purpose. This is often treated with too little care. Additional ground rods can be added to improve the grounding. A very effective ground can be accomplished by fastening the grounding conductor to the well casing if the casing is steel and IF the attachment is done properly. MANY GROUND CONNECTIONS ARE INEFFECTIVE BECAUSE OF POOR ATTACHMENTS.
- Install secondary lightning arresters
Secondary lightning arresters can provide a degree of protection when properly installed. They have received adverse publicity because so many have been improperly grounded. Arresters should be UL approved.
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