Parallel operation of alternators

All we know that the demand of power is increasing day by day. For applications on ships, alternators often are driven by dc motors. The alternators should be of the same type so as to generate voltages of the same waveform. Advantages of Parallel Operating Alternators When there is maintenance or an inspection, one machine can be taken out from service and the other alternators can keep up for the continuity of supply.

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When the frequencies are nearly equal, the two voltages incoming alternator and running system will alter the phase gradually. In general, the proper amount of field excitation for alternators operating in parallel is the amount of excitation each alternator would need if it were carrying its load alone at the same voltage and frequency.

Parallel Operation of Alternators | Devices | Electrical Engineering

The process of connecting one machine in parallel with another machine or with an Infinite Busbar system is known as Synchronizing. Since two of the lamps are becoming brighter as one is dimming, it's easier to determine the moment when the paralleling switch can be closed. The three lamps will light and go out in unison at a rate which depends on the difference in frequency between alternstors two alternators.

When alternators are of sufficient size, oeration are operating at different frequencies and terminal voltages, severe damage may result if they are suddenly connected to each other through a common bus.

One prime-mover governor is opened while the other is closed simultaneously. They are connected parallel by means of transformer and transmission lines. We highly respect your findings. Two alternators are paralleled whenever the power demand of the load circuit's greater than the power output of a single alternator. By making slight adjustments in the speed of alternator G1 the frequency of the machines can be equalized so that the synchronizing oepration will light and go out at the lowest possible rate.

Parallel Operation of Alternators | Devices | Electrical Engineering

Energize the prime mover to drive the second alternator, G1 Adjust the speed of the alternator to the approximate value required to match the frequencies of the alternators. In practice the voltage of the on-coming generator is usually volts higher than that of the other operating generator.

During paralleling process, the incoming alternator should be in phase and it should stay in phase slternators paralleling under normal condition. The bulbs will show dim and bright all together if phase sequence is alternafors same.

The three lamps will brighten and then dim in unison. If a generator loses prime mover power, it acts as a alternxtors with a dc field on the rotor. Governor control switches are mounted on the switchboard so that the operator is able to watch the switchboard instruments while making adjustments of load division.

Two volt alternators are to be paralleled. Breaking down of a generator does not cause any interruption in the supply. Their emfs E 1 and E 2 will be practically in phase opposition, as shown in Fig. In practical, a single alternator cannot meet the power demand.

Effect of Increasing the Driving Torque 9. When two alternators are in step, they are said to be in patallel. The operator then may proceed to the next step in synchronizing the alternators.

Thus the two machines come again in synchronism. The synchroscope is connected across one phase only. When the driving torque of one of the alternators is increased e. For this reason, the kilowatt load delivered by two alternators in parallel cannot be divided in any desired proportion by varying the dc field excitation of either machine.

As a result, it's possible to close the paralleling connection while there is still a large voltage and phase difference between the machines. The RMS line voltage terminal voltage of the bus bar or already running machine and the incoming machine should be the same.

The ones who are crazy enough to think they can change the world are the ones who do. The pointer rotates clock wise when an alternator is running fast and counterclockwise when an alternator is running slow. The resultant emf, E R being equal to E 1 — E 2acts in the local circuit and causes synchronising current I sy around the local circuit.

Close the switch at the exact instant that two lamps are at their brightest and the other lamp is out. Departure from the above conditions will result in the formation of power surges and current.

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