Oil Sealed Rotary Vane Vacuum Pump Fail to Start

When the vacuum pump cannot be started, first confirm whether it is an electrical control problem, and check whether the control circuit and control components are normal. If it is not a fault in electrical control, then check the mechanical part of the vacuum pump. The common reasons are as follows:

① The power supply or control circuit is not connected correctly

② The power supply voltage to the motor does not match the motor

③ The motor fails

④ The pump oil temperature is lower than 10℃

⑤ The pump oil is too viscous

⑥ The exhaust filter or exhaust pipe is blocked

⑦ The pump was stuck due to sucking in a large amount of debris

Incorrect Connection Of Power Supply Or Control Circuit

Check whether there is any problem with the main circuit and the selected accessories, and whether there is a problem with the control circuit, such as the connected circuit breaker and contactor. When connecting the pump, use cables and connectors with appropriate ratings and appropriate motor protection switches to ensure that the wiring is secure.

Solution: Have the power cord checked and repaired by a professional electrician.

Note: The direction of rotation must be checked after connecting the motor or changing the connection. To do this, close the power switch of the motor for a short time and observe whether the cover on the air inlet is sucked. Otherwise, replace any two phase wires.

The Power Supply Voltage To Motor Does Not Natch The Motor

The vacuum pumps produced by most vacuum pump manufacturers are used in many countries around the world, so there are different versions of motors. Please make sure that the power supply matches the nameplate of the motor before supplying power.

Solution: If the voltage and frequency do not match, replace the motor.

Motor Failure

First remove the motor separately and turn the vacuum pump side coupling by hand to confirm that the pump is not stuck, indicating that there is a problem with the motor.

Check whether the motor is stuck.

Check whether the three-phase resistance of the motor is balanced, whether it is burnt, and whether the ground insulation resistance meets the requirements.

Pump Oil Temperature Lower Than 10℃

The pump was used in an environment with a temperature lower than 10°C, causing the pump oil temperature to be lower than 10°C. When the pump is turned on, it is difficult to start due to the low temperature of the pump oil. Long-term low-temperature operation may cause the motor to burn out if it is not shut down in time.

Solution: heat pump and pump oil or use other types of pump oil (pump oil with lower viscosity), or open the air inlet of the pump and manually jog the pump.

Note: The jog time should not exceed 10 seconds each time.

Pump Oil Is Too Viscous

If the pump oil is contaminated or used for a long time, the viscosity becomes thicker and the oil is deteriorated. If the pump oil is too viscous, it is difficult to start. Observe the oil window or release a small amount of oil to confirm whether the oil has deteriorated.

Solution: replace the pump oil, pay attention to simple cleaning of the pump cavity or oil tank, add a little new oil, start the vacuum pump, and add new oil after the oil is drained.

The Exhaust Filter Or Exhaust Pipe Is Blocked

The exhaust filter or pipeline is blocked, causing the pump exhaust pressure too high, the pressure in the cavity too high, and the load too high, which causes the pump to fail to start normally.

Solution: clean the filter or exhaust pipe, and ensure that the diameter of the exhaust pipe of the pump ≥ the diameter of the exhaust port of the pump.

The Pump Was Stuck Due To Pumping Large Amount Of Debris

There is foreign matter in the pump or a large amount of sundries have been sucked into the pump, causing it to be stuck, and the pump cannot be started normally.

Solution: First turn the motor fan by hand. If it does not turn, remove the motor and check whether the pump is stuck. If the pump is stuck, the pump needs to be disassembled to confirm the cause of the fault and further deal with it.


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