Hitachi Industrial Equipment Systems Co., Ltd.

Hitachi, Ltd.

Hitachi Construction Machinery Co., Ltd.

Tadahiro Shimozono

Takeshi Obata

Kouji Obata

Koichiro Saito

Osamu Matsumoto

Hiroyuki Mikami

Atsushi Abe

Masami Ochiai

Kazuo Nishihama

Keiichiro Kaihatsu

Keiji Fukushi

Yoshiomi Jojima

An object of the present invention is to provide a squirrel-cage induction motor with high efficiency. In a squirrel-cage induction motor including a stator in which stator windings are wound in a number of stator slots arranged at intervals in the vicinity of the inner periphery of a stator core and a rotor in which rotor conductors are embedded in a number of rotor slots arranged at intervals in the vicinity of the outer periphery of a rotor core and end rings are provided at both ends of the rotor core, the rotor core is formed of a plurality of blocks, an annular short-circuit ring is provided between respective blocks of the rotor core to short-circuit the rotor conductors, and laminated thickness of the rotor core is made larger than laminated thickness of the stator core.

Squirrel-cage induction motor

Apparatus and method for partial discharge detection of turn-to-turn insulation in motor has a surge generator for generating a surge voltage to the windings of the motor by applying a pulse voltage, and a partial discharge current detector for detecting partial discharge currents between the winding turns of the motor. The surge generator generates in and between the windings of the motor the surge voltage that has the rise time and fall time corresponding to the rise time of the surge voltage observed at the motor terminal when the motor is driven by an inverter, and that is repeated at a frequency of 50 Hz to 20 kHz.

Apparatus and method for detecting partial discharge at turn-to-turn insulation in motor

A squirrel cage induction motor includes: a stator core (); a plurality of stator slots () radially disposed in a circumferential direction of the stator core () with predetermined intervals; a plurality of stator windings () housed in the stator slots respectively; a rotor core (); a plurality of rotor slots () radially disposed in a circumferential direction of the rotor core () with predetermined intervals; a plurality of rotor conductors () housed in the rotor slots () respectively. The stator windings () and the rotor conductors () includes electrically conductive materials mainly composed of copper. An area ratio of a total area of the stator slots () to a total area of the rotor slots () is not smaller than 2.7 and not greater than 8.0 to provide compatibility between the starting characteristic (starting torque) and the steady characteristic (for a high efficiency) can be provided.

Squirrel cage induction motor and squirrel cage induction motor driving system

A frequency converter for outputting a power to drive a motor, having: an inverter unit for inverting a d.c. power to an a.c. power; a control unit for controlling the inverter unit; and a housing for supporting at least the inverter unit and control unit, wherein a rise time change unit is provided in the housing, the rise time change unit changes a rise time of a waveform of a voltage output from the inverter unit.

Frequency converter, motor, motor drive system and maintenance method for motor drive system

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Yachiyo, Japan

Tadahiro Shimozono