Sample is connected to the fixture of the equipment ,and placed into the oil bath which Temperature is maintained at TF-10℃(oil bath should be equipped with a stirrer and temperatures controllable).A detect current about 10mA ) is passed through the sample and a thermometer is placed adjunction to the sample to monitor the opening temperature. The temperature of the oil bath is raised at the rate of 0.5-1℃ per minute until the sample functioned.

    (If the test is conducted in an oven (Air circulate type), take care that the thermometer should be placed immediately adjunction to the sample to achieve accurate test date).