The transformer is a vital electrical device. During long-term operation of fiber Bragg grating temperature measurement equipment, parts inside the transformer such as the core shaft, clamps, windings and iron core heat up due to resistance, magnetic leakage and other factors. Such heating causes the temperature to rise, decomposes the transformer insulation oil, affects oil quality, increases the internal pressure of the transformer, reduces the flame retardancy of the insulation oil, and may cause transformer explosion and damage, leading to safety accidents and large-scale power outages. Under normal operation of the transformer, the insulation oil temperature is within 105℃; the winding temperature measured by wireless temperature measurement devices is within 140℃; local mild overheating is 170-200℃; local moderate/severe overheating is 300-400℃; and some core shafts and clamps can reach 700-1000℃. Generally, the oil temperature and winding temperature are related to the natural environment and load conditions.

In the past, due to the high insulation requirements inside the transformer and the high electromagnetic interference inside, the temperature of these heating parts could not be detected. Only the overall temperature could be detected, or the oil temperature could be judged by analyzing the gas composition dissolved from the insulation oil. It was impossible to determine the temperature of an exact point, so it was difficult for wireless temperature measurement companies to identify the cause of overheating, to distinguish critical from non-critical local overheating, to predict accident hazards in advance, or to provide effective and fundamental suggestions for the structural design of the transformer.

The high-voltage cabinets of the substation are also vital electrical equipment. As the most widely used current-carrying equipment in the power supply system, 35kV high-voltage cabinets generate heat during long-term operation due to oxidation, dust, looseness, overload, poor contact and other reasons of their components, and these heating parts can easily lead to safety hazards.