Facility Maintenance Decisions

Emergency Power: Key Maintenance Practices for Generators





Gasoline or liquid propane (LP) gas generators use a gas-driven engine connected directly to an electric generator. In a typical application, the gas engine starts automatically in an emergency, turning the generator rotor and inducing an electric current in the stator. It continues to produce power as long as the engine runs.

A stationary gas engine uses a starter connected to a battery and electrical system, cooling system, lubrication system, fuel system, and drive train. It also uses a transfer switch that interlocks with the main power system to shift power sources in an emergency.

Each of these subsystems in gas and diesel engines has unique inspection, troubleshooting, and repair needs. The best way to maintain these units is to give attention to each major component.

The transfer of power in an emergency starts when the transfer switch receives a no-power signal, indicating failure in the main power source. The transfer switch disconnects from that source and connects the battery to the starter, starting the engine through the engine’s electrical system.

The drive train connects to the water, oil, and fuel circulating systems and to the emergency generator, which begins producing electricity as soon as the engine begins to rotate.

Inspection and maintenance procedures consist of making sure water, oil, gas, and battery electrolytes are available in the proper quantity and condition. Technicians can easily overlook this step, but because the emergency equipment is idle most of the time, evaporation, leakage or contamination can take their toll.

Technicians tend to lubricate other components, such as bearings requiring grease, infrequently because of low operating time. The danger with these components is overgreasing, which forces open seals and allows moisture into the bearing grease cavities, causing premature corrosion and bearing failure.

Technicians also should actuate and test the transfer-switch mechanism at least monthly, and they should make sure the contacts are bright and smooth. If they are dull or oxidized, technicians can polish them to improve contact so good current flow occurs without arcing at the contacts when they close.

The battery requires the same visual inspection as other batteries — a frequent voltage and specific-gravity check to ensure the battery is fully charged.

The charger is usually an integral part of the emergency system and has automatic on-off controls. When the charge decreases to the preset level, the charger kicks on and brings the battery to full charge, then shuts off.

Even though charging is automatic, technicians should actuate the charging system at least once a month to ensure it works properly and at the right time to keep the battery sufficiently charged.




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  posted on 4/1/2009   Article Use Policy

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