April 18, 2021

What causes the excessive no-load current after the oil pump motor is repaired? Listen to what Dalan Motor says!

What causes the excessive no-load current after the oil pump motor is repaired? Today, the editor of Dalan Motor will help you check one by one!

1. Increased air gap

The main reason is: because the rotor of the oil pump motor rotates in the ventilation air containing certain impurities for a long time, the air gap is increased due to the wear of impurities and dust in the air. The air gap increases by about 15%.

The motor is bored or the iron core is eccentric, and the rotor is turned during maintenance to increase the air gap.

Second, the core loss increases

(1) When repairing, because the uneven notch affects the embedded wire, use a large file to file the large notch to short-circuit the iron core punch of the notch, increase the size of the notch, and increase the effective air gap of the motor.

(2) The iron core is corroded and rusted in a humid environment for a long time.

(3) When the winding of the oil pump motor was dismantled, an incorrect method such as burning an iron core was used to corrode the insulation of the iron core punches and short-circuit between the punches.

(4) The rotor core is not aligned with the stator core, or the rotor core is reversed.

(5) The iron core has severe fan-out phenomenon.

3. The number of winding turns is reduced or the coil pitch becomes smaller

The decrease in the number of coil turns increases the magnetic flux density, and the core loss is proportional to the square of the magnetic flux density, resulting in a large increase in iron loss. The coil pitch becomes smaller, so that the short-distance coefficient of the winding is reduced, and the effective number of turns of the motor is reduced. The effect is also to increase the iron loss and increase the no-load current.

4. Incorrect winding wiring

For example, 1Y connection is mistakenly connected to 1Δ connection, 1 way is wrongly connected to 2 ways, etc.

The 1Y connection is mistakenly connected to 1Δ connection, which is equivalent to a reduction of √3 times the number of turns per phase winding; 1 way is incorrectly connected to 2 circuits, the number of turns per phase winding is reduced by 50%, resulting in a large increase in no-load current.

5. Improper installation of the motor rotor makes the air gap uneven, or the bending of the rotating shaft, bearing failure, etc., will increase the no-load current.

As the no-load current increases, the motor power factor decreases. When the rated voltage UN and the rated current IN of the motor are kept unchanged, the output power of the motor decreases due to the reduction of the power factor. If the motor is running under a rated load, the motor will heat due to excessive current.

----- Responsible Editor: Dalan Oil Pump Motor 02-Procurement Consultant

Copyright http: / (Dalan Motor) Reprint, please indicate the source

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