Synchronization is the term used to describe Connecting an alternator to grid In parallel with a variety of alternators, which is the same live system of constant voltage and frequency. Numerous alternators and loads are plugged to a grid. all the alternators that are part of grid have the identical output voltage and frequency (whatever is the source of power). It is also believed that grids have the same frequency and voltage. alternator is connected to an infinite bus-bar.
An alternator that is stationary cannot be connected to live bus-bars as it can cause short circuits in the stator’s winding (since there isn’t any EMF as of yet). Before Connecting an alternator to grid The following conditions must be fulfilled:
- Equivalent voltage at the terminal of the alternator’s incoming supply should be at least equal to the voltage of the bus bar.
- Similar frequency The frequency of the produced voltage should be the same as the frequency of bus-bar voltage.
- Sequence of the phase: The sequence of the three phases of an alternator should be identical to the bus-bars and grids.
- Angle of phase: The angle between the voltage generated and grid voltage must be zero.
The first requirement for voltage equality is easily met with an voltage meter. To meet the requirements that equal frequencies and similar phases One of two approaches is possible:
(i) Synchronization using incandescent lamp
(ii) Synchronization using synchroscope.
Synchronization of Alternator Using Incandescent Lamp
Alternator 2 needs to be synchronized with a grid , and the alternator 1 is already on the grid as illustrated in the above illustration. The alternator 2 is connected with the grid via the three lamps that synchronize (L1 L2, L2 and L3) as illustrated in the above diagram. When the frequency of the alternator isn’t enough to ensure as to ensure that its frequency the output voltage is the same as grid frequency and grid, there could be some phase differences in the voltages. In this scenario, the lamps will flash. 3 lamps can be connected asymmetrically since if they were connected to each other in a straight line, they would either glow or dim out at the same time (if the rotation of the phase is the same as the bus-bars). Asymmetrically connected lamps show the machine that is operating slower or faster. If alternator 2 is operating slower, the phase motion of alternator 2 appears to be clockwise in relation to the grid’s phase grid, and the lamps will be lit in the order of 3,2,1;3,2,1. …. If alternator 2 is running more quickly the phase rotation that alternator 2 is displaying will seem be counterclockwise with respect to the grid’s phase rotation which means that the lamp will illuminate in the order 1,2,3 ….
When the speed of alternator 2 increases to the point where it is at a level where the frequency and phase rotation of the output voltage is the same as the voltage of grid, the lamp L1 will turn dark while lamps L2 and L3 will be dim, but they will both shine (as they are linked between different phases, and because of this, there will be a phase divergence of 120 degrees). The synchronization process is happening in this moment. The method used to synchronize can be called ‘ Two bright and one dark method ‘.
Cons of synchronization with lamps made of incandescent’ The methods are:
- Synchronization using incandescent lamps relies on the judgement by the user.
- This method cannot reveal how fast or slow the machine is.
- For this to be used for the high-voltage alternators additional step down transformers have to be included since the their ratings for lamps are usually not high.
Synchronization Of Alternator Using Synchroscope
The Synchroscope is a device that displays the exact time of closing the synchronizing device. Synchroscope is equipped with an indicator that rotates around the dial. The pointer turns anticlockwise when you find that your device is not running as fast or clockwise if the machine is speedy. The proper time to close the syncronizing switch happens in the moment that it is pointed to the left.