Patent ID: 8918301

Claim:
A motor condition inspection method of inspecting a condition of a three-phase motor installed in an apparatus without removing the three-phase motor from the apparatus, the method comprising: preparing a motor characteristic inspecting device that comprises: an angular range detecting section configured to detect a predetermined angular range including a peak value of a counter electromotive force for one phase among counter electromotive forces for three phases generated in armature windings of the three-phase motor when a mover of the three-phase motor is moved with no power supply, the predetermined angular range being less than 180° in terms of electrical angle; a three-phase-to-two-phase converting section configured to convert the counter electromotive forces for three phases into a two-phase AC voltage equivalent to the counter electromotive forces for three phases through αβ conversion such that α axis indicates the counter electromotive force for one phase; a vector variation computing section configured to compute a voltage vector variation amount which is an amount of variation in voltage vector in the predetermined angular range, based on an amount of variation in α component and an amount of variation in β component in the predetermined angular range; a speed variation detecting section configured to detect a speed variation amount which is an amount of variation in speed of the mover in the predetermined angular range; a constant computing section configured to compute a counter electromotive force constant based on the speed variation amount and the voltage vector variation amount; and a result display section configured to display a predetermined indication for a computed result or an expected computed result of the counter electromotive force constant; electrically connecting the armature windings and the motor characteristic inspecting device with power supply lines disconnected from the three-phase motor installed in the apparatus; applying an external force to the mover of the three-phase motor to generate the counter electromotive forces in the armature windings; and determining a condition of the three-phase motor based on the computed result displayed on the result display section of the motor characteristic inspecting device.