Transformer pressure type thermometer is used for the internal temperature of a transformer winding and to monitor and control the temperature of transformer oil. As the electric power system stable operation of power grids of the demand is higher and higher, the substation transformer pressure type thermometer temperature measurement accuracy and precision of data is becoming more and more high, but because of various reasons, meter field of temperature measuring temperature data can not fully reflect the transformer top oil temperature in actual temperature, at the same time, the temperature difference of the scene and the background will be very big, the background is we need to find out the source of the error of the thermometer. Pressure type thermometer temperature error source has the following several reasons: altitude, static liquid injection and the influence of the external environment; Measurement and human error; Meter itself design and quality of work; The influence of non-electricity measurement channels; The influence of current transducer and temperature module; The influence of measurement and control device and monitor configuration errors; The influence of oil temperature package insert seat depth; Other ancillary equipment design error, etc. One, the influence of environment temperature on the error in transformer pressure type thermometer spring tube and the capillary is filled by thermal liquid medium, environment temperature and indexing instructions at the same time, not interfere with the value in the certain error. Over or under room temperature, the temperature deviation, the greater the error caused by temperature, the greater the best instrument surrounding temperature does not exceed 50 ℃. Second, the package insert depth the deeper the package insert the influence of the error, temperature error value is smaller, when fully inserted into the minimum error value. Three, installation and use of transformer pressure type thermometer improper installation type temperature time must pay attention to the spring and the bulb at the same height as far as possible, when high temperature bag is bigger than the actual value, value for bulb low value is smaller than the actual value, but also pay attention to protect capillary, not multiple bending and impact, and sharply or damage to the sealing, as far as possible to avoid corrosion effects of capillary and spring, when using bulb don't exceed the upper limit of temperature measurement.