The transformer temperature rise test is included in the transformer type test. In this test we check if the temperature rise limit of the transformer winding and the oil according to specification or not.
Temperature rise test for transformer upper oil
1. First, the transformer winding LV is short-circuited.
2. A thermometer is then placed in a pocket on the top of the transformer. Two other thermometers are placed at the inlet and outlet of the refrigerator bench respectively.
3. The voltage of such a value is applied to the HV winding that the power input equals the uncharged losses plus the corrected load losses at a reference temperature of 75 ° C.
4. Total losses are measured by the three-meter method.
5. During the test, the hourly readings of the upper oil temperature are taken from the thermometer already placed in the upper cover pocket.
6. The time readings of the thermometers placed at the inlet and outlet of the refrigeration bench are also shown to calculate the average oil temperature.
7. The ambient temperature is measured by a thermometer placed around the transformer in three or four points at a distance of 1 to 2 meters from the cooling surface of the transformer and half way up.
8. The temperature rise test for the upper transformer oil must continue until the upper oil temperature has reached an approximate constant value which means that the test will continue until the upper oil temperature rise becomes less than 3oC In an hour. This constant value of the upper oil is determined as the final temperature rise of the transformer insulation oil.