Electrical Machine: Transformer Tap Changer

Transformer Tap Changer

Tap-changer is a device changes the voltage ratio of transformation to get a better secondary operations (desired) of the network voltage / primary fickle.

To meet the voltage quality of service according to customer needs (electricity distribution), the voltage output (secondary) transformer must be changed as desired. To meet this, then on one or on both sides of the transformer winding is made tap (bugs) to change the transformation ratio (ratio) transformer.

There are two methods tap changer:

Changing the taps in the transformer no-load conditions. Tap changer which can only operate to move the transformer tap transformer in a state does not load, called "Off Load Tap Changer" and can only be operated manually.
Changing the load transformer tap-in condition. Tap changer which can operate to move the tap-transformer, the transformer load condition, called "On Load Tap Changer (OLTC)," and can be operated manually or automatically

Transformers installed in substations typically use tap changer can be operated in a state loaded and installed in a transformer primary side. While peppery voltage transformer in a transformer plant, or in a small capacity, typically using a tap changer is operated only during power transformers without load.

OLTC consists of:
1. Selector Switch
2. deverter switch
3. transition resistor

To isolate the transformer from the body (ground) and reduce the heat transfer process at the tap, the OLTC immersed in insulating oil which is usually separate from the main transformer insulating oil (there are several transformers that compartment become one with the main tank).

Because the process of switching tap relations phenomenon occurred in the oil-electric, mechanical, chemical and heat, the OLTC insulation oil quality will quickly decline. depending on the number of works and the presence of abnormalities in OLTC.

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