Article title: requirements of parts and components for temperature rise test of transformer

Key words: transformer, temperature rise test, parts, components, requirements

Overview: when the transformer operates under the specified rated conditions, the temperature rise of its winding, magnetic circuit and any other parts shall not exceed the corresponding values listed in Table 1-1. These values correspond to the service conditions listed in table 1-2.

The temperature rise of winding is limited by the lowest insulation level of the winding itself or the surrounding medium embedded in the winding. If the transformer is installed in the enclosure, pay attention to the temperature of the ambient cooling medium in the enclosure.

1. General requirements

When the transformer operates under the specified rated conditions, the temperature rise of its winding, magnetic circuit and any other parts shall not exceed the corresponding values listed in Table 1-1. These values correspond to the service conditions listed in table 1-2.

The temperature rise of the winding is limited by the lowest insulation level of the winding itself or the surrounding of the embedded winding).

If the transformer is installed in the enclosure, pay attention to the temperature of the ambient cooling medium in the enclosure.

If the specified ambient temperature exceeds the values listed in table 1-2, the allowable temperature rise in Table 1-1 shall be less the value of the excess part of the ambient temperature.

2.Test method for temperature rise of transformer

(1) The temperature rise test of voltage transformer is generally carried out with zC-501a high-voltage test transformer produced by kvtester. See the article 《temperature rise test method of voltage transformer for specific test method》;

(2) The temperature rise test of current transformer is generally carried out with zc-510 large current generator produced by kvtester. See the article 《temperature rise test method of voltage transformer" for the specific test method》.

3. The influence of altitude on temperature rise

If the transformer is specified to be used at an altitude of more than 1000 and the altitude of the test site is less than 1000m, the temperature rise limit △t in Table 1-1 shall be subtracted from the following value every 100m after the altitude of the use site exceeds 1000m (see Figure 1-1):

a)     Oil immersed transformer: 0.4%;

b)    Dry and gas insulated transformers：0.5%

Altitude correction factor for temperature rise K0=△Th /△Th0

In the formula:

△Th  —Altitude h > Temperature rise at 1000M

△Th0 —Figure 1-1 temperature rise limit △T (Altitude h < 1000m)