Working principle and operation of power transformer tap changer

Working principle and operation of power transformer tap changer

1、 Working principle

The tap changer of power transformers mainly changes the voltage ratio by changing the tap of the high-voltage winding to increase or decrease the number of winding turns. In the process of transmitting electrical energy in the power system, there will inevitably be losses in both voltage and power. Using transformers to increase voltage can effectively reduce power transmission losses. As a very important component of transformers, the on load tap changer uses a transition circuit to control the circulating current, thereby achieving the switching of the tap changer without affecting the continuity of the load current.

In addition, on load tap changers for transformers are mainly divided into two types: reactive and resistive. A resistive tap changer is usually placed in a small oil tank independently separated from the transformer's oil tank to place the switching device. This small oil tank is not connected to the transformer's oil.

2、 Operation

Regarding the operation of power transformer tap changers, certain steps and safety measures need to be followed:

1. Operation steps:

-Remove the protective cover of the tap changer.

-Repeatedly rotate the handle of the tap changer.

-Adjust the handle to the predetermined position.

-Tighten the positioning bolts.

-Use a multimeter to roughly measure the resistance.

-Use an electric bridge for precise measurement of resistance.

-The test data shall be calculated and the gear adjustment shall be completed after confirming that the requirements are met.

-Perform pole to ground and inter pole discharge operations.

-Dismantle the test line and restore the original wiring of the transformer.

2. Safety measures:

-Ensure that technical measures are complete, including steps such as power outage, electricity inspection, discharge, and hanging ground wires.

-When measuring resistance, power must be cut off and the high and low voltage leads must be removed.

-For large transformers, discharge operations should be carried out before and after testing.

-Always pay attention to maintaining a safe distance from live equipment.

In general, the working principle of power transformer tap changers involves changing the number of winding turns to adjust the voltage ratio, and the operation process must strictly follow the steps and safety regulations to ensure the normal operation of the transformer and the stability and reliability of the power system.