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There are many reasons leading to the vibration of unit and pump house buildings. Some factors are related and interact with each other.

1. Electrical

The main cause of the unbalance of the generator set and other electrical equipment is the unbalance of the motor and the electrical system. For example, in the operation of asynchronous motor, the radial alternating magnetic pull force between stator and rotor caused by harmonic flux interaction between stator and rotor, or large synchronous motor in operation, the magnetic center of stator and rotor is inconsistent or the air gap difference in each direction exceeds the allowable deviation value, etc., which may cause periodic vibration and noise of the motor.

2. Mechanical aspect

Strong vibration and noise will be produced due to mass imbalance, rough manufacturing, poor installation quality, asymmetric unit axis, swing exceeding allowable value, poor mechanical strength and stiffness of parts, wear and damage of bearing and sealing parts, and resonance between critical speed of water pump and natural frequency of unit.

3. Water power

The uneven distribution of flow velocity and pressure at the pump inlet, the pressure pulsation of the working liquid at the pump inlet and outlet, the flow around, the bias flow and the flow separation of the working liquid at the pump inlet and outlet, as well as the pump cavitation caused by various reasons under non quota conditions are the common causes of pump unit vibration. The rapid change of water pressure and water hammer caused by the dynamic transient processes such as pump start-up and shutdown, valve opening and closing, working condition change and emergency shutdown also often lead to pump house and unit vibration.

4. Hydraulic and other aspects

The unreasonable design of the inlet channel of the unit, the improper submergence depth of the water pump, and the unreasonable start-up and shutdown sequence of the unit will worsen the water inlet conditions, produce vortices, induce cavitation or aggravate the vibration of the unit and pump house. When the unit using the breaking siphon vacuum cut-off is started, if it is difficult to carry the air in the hump section, the siphon time will be too long; the clapper door design of the unit with flap valve cut-off is not reasonable, sometimes open and close, and constantly impact the flap door seat; uneven settlement of the foundation supporting the water pump and motor or poor rigidity of the foundation will also lead to the vibration of the unit.

Technology Department