Squirrel cage rotor has been applied in electric motor productions widely at present. For testing whether the product is qualified or not,  the simple test solution could be applied. However, the professional squirrel cage rotor test system must be applied to test the squirrel cage rotor in the industry production.

(1) Rotor bar broken fault phenomenon and the causes of productions

   Motor with broken bar: Rotor bar broken will make it difficult to start the motor, the motor will produce strong periodic electromagnetic noise and vibration, the three-phase ammeter pointer jitter, the motor with load capacity reduced. The speed goes down.

The reasons for rotor bar broken are: poor manufacturing quality, motor start frequently. Improper operation. The rotor is damaged by violent impact caused by frequent positive and negative rotation.

(2) The inspection method of rotor bars broken

The inspection method of rotor broken bars is described below.

(1) External inspection method: in the motor running, if the rotor and stator gap sparks appear. It indicates that the rotor bars have broken. You can also look at the ammeter, whether the pointer is jittering or not, motor speed and load capacity to judge. Then extract the rotor. Looking for the broken points.

(2) Current test method: the three-phase voltage regulator is used to apply a low-voltage power supply to the stator windings for testing (the motor with a rated voltage of 38OV can apply a voltage of about 100V). To add an ammeter in a phase. Slowly turn the rotor by hand if the cage bars are intact. The ammeter has only a slight uniform swing; If the rotor is with broken bars. Then the ammeter will suddenly drop the pointer.

(3) Testing with detector: Disassemble the motor. Remove the rotor. The position of rotor bars was determined by electromagnetic induction. If the squirrel-cage bars are intact. The millivoltmeter reading is small; If the rotor is with broken bars. The reading will be larger.

 (4) Testing with iron powder: In the rotor at both ends of the ring supply the great current with high voltage. Dust the rotor surface with iron powder. Magnetic field lines are generated by the current passing through the squirrel-cage bars. Magnetic lines of force will attract iron powder. If you find a squirrel cage bar around the iron powder is very small. Then the place is broken. 

The squirrel-cage rotor test system of Qingdao AIP Intelligent Instrument Co., Ltd. has automatic test and semi-automatic test system, the series product is suitable for all kinds of squirrel-cage rotor production test, can efficiently and stably analyze the squirrel-cage bars broken, bars short circuit, bars slot full rate, bars Angle and so on and provide professional judgment and analysis for users.