Abstract: The present invention relates to a resistor device for controlling a rotational speed of a motor which has no directional property and provides a convenient setting. A resistance unit is positioned which includes at least four connecting points connected to connecting terminals at an upper predetermined position of a housing, and a heat sink having at least four supporting legs is provided to form passing paths open in all directions on the housing. Also, the resistance unit is adhered on the heat sink through an insulating layer, a second heat sink corresponding to the first heat sink is adhered on the resistance unit through the insulating layer, and short-circuit means having a soldered portion to be fused at a predetermined temperature upon an overloading of the motor is provided between the resistance unit and any one terminal.

Abstract: A resistor device for controlling a rotational speed of a resistance unit and an open-circuit means. A receiving recess is provided to any one side surface of a heat sink vertically affixed to a top surface plate of a housing. A resistance unit, which is protected by a film and made of metal material forming a resistor circuit for gradually controlling the rotational speed of a motor, is received within the recess in the heat sink and connected to a terminal. An open-circuit means, having a soldered portion which is fused at a predetermined temperature upon an overload of the motor, is provided at a predetermined distance between the resistance unit and a terminal.

Abstract: A resistance unit has a temperature fuse between a resistance and a terminal for deactivating a resistance circuit when the motor reaches the permissible maximum temperature.The resistance unit having resistance connected in series with a plurality of terminals for controlling the speed of a motor comprises at least one temperature fuse electrically interposed between one of the terminals and one end of a corresponding one of the resistances for deactivating the resistance circuit when the resistance unit is overheated.