Test method for temperature rise of special transformer

The temperature rise experiment of special transformers is usually carried out after the insulation, loss, voltage ratio and DC resistance experiments, according to the nameplate data or relevant rules. The purpose of the temperature rise experiment is to determine whether the temperature rise of each part of the transformer can meet the relevant specifications. Therefore, it can provide a stable basis for the long-term safe operation of special transformers.

The following are some common experimental methods for temperature rise experiments:

1. When the temperature rise experiment adopts the direct load method, connect an appropriate load (such as an electric furnace, inductor or capacitor, etc.) to the secondary side of the tested special transformer, apply the rated voltage to the primary side, and then adjust the load to make the load current equal to rated current.

When the temperature for 4 weeks is 20 ± 5 degrees Celsius, or the cooling water inlet temperature is 2025 degrees Celsius, the rated current is allowed to be used as the experimental condition without correction. At this time, the voltage applied to the primary side should be equal to the rated value of the tap. Voltage, deflection shall not exceed ±2 percent.

The experimental conditions of the direct load method are different from the operating conditions, and the measurement results are accurate and stable. This method should be used as much as possible when conditions permit. However, the power supply capacity required for this experiment is larger than the capacity of the tested product, and it is difficult to find the appropriate Therefore, it is more suitable for the temperature rise experiment of small-capacity special transformers and dry-type transformers.

2. Use the short-circuit method to do the wiring of the temperature rise experiment

1. Make sure the temperature rise of the upper coil of the tested transformer. Adjust the applied voltage so that the power of the special transformer to be tested is equal to the sum of no-load loss and short-circuit loss, and then stop the experiment after the loss equivalent to the operating condition is formed.

2. After participating in the experimental current of the equivalent loss of the equipment under test, the temperature rise of the upper, middle and lower coils and iron core of the transformer should be measured regularly.

3. Determine the temperature rise of the winding. Reduce the voltage so that the power input to the device under test is equal to the short-circuit loss, and measure the temperature of the same parts as the item regularly until the stable temperature of each part is measured, and then calculate the temperature rise of the winding.

4. Confirm the temperature rise of the iron core. Remove the short path of the tested equipment, and stop the no-load temperature rise experiment at rated frequency and rated voltage.