| 摘要 |
PROBLEM TO BE SOLVED: To provide a thermal protector which protects a three-phase motor from burning. SOLUTION: The thermal protector 1 contains two pairs of contact mechanisms consisting of movable contacts 9A and 9B and stationary contacts 13A and 13B in a container. The stationary contacts are connected and fixed to conductive terminal pins 5A and 5B respectively and the movable contacts are fixed on a heater 8. The heater 8 is connected to a housing 2 with intermediary of a base plate 6 and an elastic plate 7. A heat responding plate 10 is connected to the heater 8 at about its center and held by the base plate 6 at both ends. The above contact mechanisms make switching action with displacement of the heater caused by change of bending direction of the heat responding plate. So-called indirect heating structure being applied in which the heater heats the heat responding plate, the heater also heats parts around the heat responding plate in the case of overcurrent, therefore the temperature difference between the heat responding plate and surroundings is small and the heat of the plate is hard to dissipate. Thus elongated returning time ensured consequently lowers the temperature of winding coil of a motor.
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