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Isolated generator Installation
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ISOLATED GENERATOR INSTALLATION
An isolated generator is defined to be any installation where the owner generates his own electricity.
There may be times when it is not feasible to construct the necessary distribution lines to supply power to a particular consumer. The consumer may have only modest power needs and be quite distant from other consumers. If the distribution lines were to pass a long distance through rugged country the construction and maintenance costs could be much higher than the cost of purchasing, installing and operating a low-powered generator to supply the needs of this consumer's compound.
The most common type of isolated generator produces AC power. Capacities are available from 400 to 100,000 watts. The generator should be selected to supply the same voltage at the same frequency as the power system that someday may be extended to supply this consumer. This selection has the advantages that ordinary appliances can be used and that if the system is extended to supply this compound no rewiring will be necessary, The generator must be chosen to supply the maximum load that will be required at any given time. It is wise to consider the future; perhaps a generator with a larger capacity should be selected to allow for future growth.
The manufacturers of the generating plants supply full details for the installation.
Location of Generator A generator must be located where the generator will be able to cool properly, so proper air circulation is a must. To avoid noise and fumes it is also convenient to locate the generator away from the living areas of a compound. However, the generator should be located close enough to the loads to keep voltage drops to a minimum, and the cost of conductors to a minimum.
Mounting of the Generator A generator and its engine must be mounted on a solid base. Usually a concrete slab or similar base is used. This is to prevent vibrations from damaging equipment.
Grounding It is just as important to ground an isolated system as it is to ground a larger system. The generator case should be grounded and one of the conductors for the system, should be grounded.
Metering Since the consumer owns his own generator he does not need to measure the energy that he supplies to himself. He will need to observe the voltage, frequency and current outputs from time to time to insure that the generator is operating properly and if not to make the necessary adjustments. The needed meters will be built into the generator plant and full instructions will be found in the operating manual.
Lightning Protection If there are any outdoor lines in the system the grounded line should be run above the others. It will still be necessary to install lightning arresters to protect the system and the generator from any lightning strikes to the wires of the system.
Overload Protection A generator can provide only a set amount of current. If more current is demanded than the generator can produce the generator may burn out. Therefore fuses or circuit breakers must be installed to protect the generator from delivering more power than it is designed to supply. The compound system should still be installed as any other system, with its own fuses to protect the entire system and the parts of the system from over current.
Disconnection The generator will need to be shut down occasionally for routine maintenance. There must be a switch (or the circuit breakers) to disconnect the generator from the loads. This is a must, as the generator must have no load on it when it is started. It must be running properly before any load is applied. It is also best to disconnect the load before stopping the generator.
(This page is based on information copied from Rural Electrification Systems prepared for the United States Peace Corps By: Volunteers in Technical Assistance, Inc. (VITA) 3706 Rhode Island Avenue Mt. Rainier., Maryland 20822 USA In accordance with Contract PC 251709 April, 1969.)