Transformer winding thermometer abnormal cause analysis

With the constant improvement of the requirements for safe operation of transformer, winding thermometer as a running custody the original has been more and more widely used in transformer products. Although in general the use of the thermometer statement said: 'in the thermometer is proportional to the increase of the original electric heating temperature on top of a winding and tank ( The oil level) The increase of the temperature difference '. Strictly speaking, this claim is not exact. Because of the different structure of the transformer winding, although can make within the original electric load current is proportional to the flow of electric current and winding, but because the cooling condition of the electric heating element and winding can't completely the same, which makes the same current changes are not necessarily cause the same in the winding and the electric heating element temperature change, in other words, in some cases, the temperature of the thermometer can be 'false'. So it is necessary for the actual situation of the research into the thermometer wave analysis:

the transformer winding thermometer can be thermal simulation measurement of transformer winding

fever is a transformer load loss. By P = I squared r load loss formula, the winding of fever and is proportional to the square of the current transformer. Because the transformer winding is immersed in the insulating oil, therefore, winding thermometer is on the basis of an oil temperature gauge, equipped with a current matcher, and an electric heating element. When the transformer load is zero, winding is not hot, so the thermometer reading for transformer oil temperature; After the transformer on load, through current transformer output is proportional to the load current, the current matcher adjusted through the original embedded in the corrugated tube heating, make the original electric heating. The heat generated by the original electric heating, make the elastic element displacement increased.

as a result of the elastic element has the transformer top oil displacement is temperate load current transformer, so in the design of winding temperature time, considering the current flows through the electric heating element temperature indicating temperature is generated by the indicator enhancement on top of the transformer and its approximation with transformer winding temperature rise of oil to be tested. In this way, the temperature of the winding thermometer indicator is the transformer top oil temperature of oil and winding temperature rise, the sum of it reflects the hottest part of the transformer winding temperature being measured.