PR533 is used for the verification, calibration and test of temperature measuring and controlling instruments and devices, such as temperature controller with electrical contacts, temperature switch, etc. It is especially suitable for the calibration of “transformation oil surface thermostats”and “transformation winding surface thermostats”. The bath temperature control range is usually at (0-160) °C, and the temperature can be changed at the required rate. And the bath also has a constant temperature function. Its constant speed heating rate is usually specified as 1 °C / min and its cooling rate is usually specified as - 1 ° C / min.