A tap changer is a device used in transformers to change the turns ratio between the primary and secondary windings. The turns ratio is defined as the ratio of the number of turns in the primary winding to the number of turns in the secondary winding. It determines the voltage transformation ratio of the transformer.
Here's how a tap changer affects the turns ratio of a transformer:
Primary Side Tap Changer: A tap changer on the primary side of the transformer allows for adjusting the number of turns in the primary winding. By changing the tap position, the number of turns can be increased or decreased. This, in turn, affects the turns ratio of the transformer. If you increase the number of turns on the primary side, the turns ratio increases, resulting in a higher output voltage. Conversely, decreasing the number of turns on the primary side decreases the turns ratio and leads to a lower output voltage.
Secondary Side Tap Changer: Similarly, a tap changer on the secondary side allows for adjusting the number of turns in the secondary winding. By changing the tap position, the number of turns can be increased or decreased. This adjustment affects the turns ratio, but this time it influences the input voltage. Increasing the number of turns on the secondary side results in a higher turns ratio and reduces the input voltage. Decreasing the number of turns on the secondary side leads to a lower turns ratio and increases the input voltage.
**On-load Tap Changer (OLTC