■ Test on Rated Off Temperature Place a thermal protector in a test chamber for test. The air flow rate in the test chamber should be no lower than 200m/min. (The temperature uniformity at temperature measuring area must be kept within the range of ±0.5℃.) Take a thermocouple or a thermometer for measuring and it should be placed on the sample or be kept as close as it could to the sample. Raise the air temperature of test chamber and heat up when it is 10K lower than nominal operating temperature at a heating rate lower than 1K/min until the thermal protector operates. The temperature measured should accord with prescribed GB standard. The on-off state is indicated by indicator light or other means. Current through the thermal protector should not exceed 0.01A.
■ Test on Reset Temperature Apply the method mentioned in article 1 to test reset temperature. Decrease the air temperature of the test chamber and lower the temperature when it is about 10K higher than the ceiling reset temperature at a cooling rate lower than 0.5K/min until the thermal protector resets. The temperature measured should accord with prescribed GB standard.
■ Test on Service Life Connect a thermal protector in an AC circuit of 50 Hz, with rated voltage being 250V and power factor COSΦ being 0.75～0.8. The circuit carries rated current with a current tolerance of ±5％. Frequency of operation (connect-break-connect time) is no shorter than 13min. The cycle rate of the test depends on the control of surrounding air medium temperature. After 4000 cycles, the variation of operating temperature should be within ±5℃ or ±5％ of initial value(choose the higher value of the two). There should be no weld fusion of the contact. Continue the test for 2000 times and there should be no perpetual damage on the operating performance of the thermal protector.
