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Vibration fault analysis of deep well pump
- Apr 10, 2018 -

Based on the analysis of vibration fault of large deep well pump and the possible causes of vibration, a simple judgment method of motor and pump is put forward.


The judgment of vibration fault.

Vibration occurs while the pump and motor, when the conditional, should first disconnect the coupling between the two, the analysis of vibration source is from the pump and motor, and carefully check the vertical machine base and the connection of the pump fixed bolts are tight, after installation levelness is poor.


1. Vibration source and discrimination of motor.

(1) whether the rotor speed is close to critical speed. It can be calculated by calculating the torsional rigidity of the motor shaft and whether the torsional vibration frequency of the motor is similar to the critical speed of the motor, the pump angular frequency and the power grid frequency. In particular, the first used motor, when the vibration failure, should be analyzed and calculated. The working speed of motor rotor shall be at least 25% or higher than the critical speed of about 40%. When analysis will also consider the quality of the motor rotor can not be simplified into a lumped mass, but along the axis, thus when critical speed analysis to main critical speed of the second order and third order.


(2) imbalance of motor rotor.

Motor rotor imbalance is the main and the vibration of the common reasons, such as: 17 # and 19 # motor with speed vibration (displacement) measured motor vibration velocity of 9.8 - l0mm/s, control standard IS02372 vibration speed, class III machinery should be less than 4.5 mm/s, 9.8 l0mm/s mode, and in using vibration amplitude value is 0.30 mm measured motor. In order to understanding the unbalanced degree of the motor rotor, we made two pairs of steel at the scene, respectively, set up two parallel rails (pay attention to the steel frame should have enough stiffness), on the rail surface treatment into a smooth, clean face with level adjust rail surface level and fixed. On inspection, the motor rotor is placed on the two rails, and the rotor is pushed back and forth repeatedly with the hand. After each rest, the rotor is marked under the rotor. By sticking the viscous material on the symmetrical point of the gravity position, the rotor is rotated several times until the rotor can stop at random position, and the rotor of the motor has reached the static equilibrium state. Replace the paste with equivalent quality and complete the balancing work of motor rotor. If the problem cannot be solved by the above method, the motor rotor should be tested for dynamic balance. After adding 45-5g balance weight on the rotor side of the above two motors, the amplitude value is reduced to 0.05mm, and the vibration velocity value measured by the displacement meter is about 2.1mm/s.


(3) to have normal use for a period of motor, the vibration reason to check whether the bearing clearance is too large, the rotating shaft fixed screw is loose, one part of the shaft for wear and bending or uneven winding short circuit, air gap, the annular clearance between rotor and stator uneven generally should not exceed 10%.

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