Abstract: The transfer switch (6) supplies the DC voltage supplied from the DC power source section (5), to the commercial electricity system (8) in such a way as to provide the DC voltage with the same polarity as the AC voltage generated by the commercial electricity system (8) according to the control of the commercial voltage monitor section (7) when the absolute value of the voltage of the commercial electricity system (8) is higher than the voltage threshold level. When the absolute value of the AC voltage is lower than the voltage threshold level, the supply of the DC voltage from the DC power source section (5) is interrupted. The generator (2) and the commercial electricity system (8) are isolated from each other by the isolation transformer (4).

Abstract: A concrete vibrator is disclosed in which a sensorless semiconductor motor is employed for driving an exciter. The sensorless semiconductor motor has an arrangement in which the rotational position of the permanent magnet rotor is sensed through utilization of a voltage which is induced from three-phase stator windings, i.e. a voltage which is induced according to the magnetic flux distribution in the gap and varies its frequency with the rotation speed alone instead of by using the Hall element which is readily damaged by vibration and heat, that is, seriously poor in environmental resistance. Further, the sensorless semiconductor motor is arranged so that the current supply to the stator winding is placed under control of a semiconductor inverter which is controlled by a PWM or PAM system.

Abstract: An automatic polishing device is disclosed for automatic smooth polishing of windowpane from the outside of an airplane without the necessity of removing them from the airplane. The device of the present invention is provided with replaceable petal-shaped polishing pads of the same number as a required number of polishing steps such as rough, medium and finish polishing. Each pad is mounted on the exterior wall surface of an airplane and urged against the window surface with substantially constant pressure and is supplied with liquids for polishing and washing from a centrally-disposed opening.

Abstract: A crimp cutter blade for gripping and cutting out a top end portion of a terminal wire, in which depressions or recesses are formed on a pair of opposing arms between crimping portions for crimping the terminal wires of electronic parts or the like and cutting edges for cutting them, respectively. The depressions absorb upward drift of the terminal wires which is caused by the crimping and cutting of them.