| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an overload relay for protecting a motor, which is improved so that a thermal relay does not improperly trips and operates in starting without being affected by the length of the duration of a starting time of the motor while securing the protection cooperativeness of an overload in the rated operation of the motor. <P>SOLUTION: The overload relay protects the motor from the overload and a restricted operation in conjunction with an electromagnetic switch, and is constituted such that the thermal relay 8 is combined with a current transformer 7 mounted to a main circuit 1 of the motor 2, and a heat element 8a of the thermal relay is energized with a secondary output of the current transformer. A control relay 10 connected to an output circuit of the current transformer in parallel with the heat element of the thermal relay is arranged at the overload relay as a control means that stops the energization to the heat element in the starting of the motor, a connecting point of the control relay 10 is closed in terms of polarity during the starting and a secondary circuit of the current transformer is short-circuited, and the connecting point is on/off-controlled by a timer 11 in accordance with the starting time of the motor so that the connecting point is opened in terms of polarity after the starting. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
