The plunger pump motor cannot drive it
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Our facility has newly installed two three-cylinder piston pumps. During the trial operation phase, after starting, the motors rotated at low speed for a while before stopping and failing to rotate further (the pump fluid is water, the back pressure is 5 MPa; it’s a variable-frequency pump, and at startup frequencies of 30%, 50%, and 70%, the motors would stop rotating). All that could be heard was a squealing sound from the motors, and the current level was also high, but the motors simply wouldn’t rotate； When the drain valve was opened, the pump operated normally; the pump did not have a return line installed. There is a gear reduction between the motor and the pump; please help analyze the reason, thank you! ! !
When starting a plunger pump equipped with frequency conversion, set it to the maximum value; once normal operating speed is reached, gradually reduce the frequency.
Before starting a plunger pump, it is necessary to open the pump’s outlet valve; otherwise, pressure buildup in the pump may occur, preventing the motor from rotating. Generally, the plunger pump itself is equipped with a pressure regulating valve, which must be opened before starting the pump; once it is running, the desired pressure can then be adjusted.
Even if the frequency is adjusted to 70% now, the transfer process still stops. In the past, it was possible to start operation with a very low pump frequency as well; could it be that the motor is too small and does not have sufficient torque?
Turn the shaft by hand before starting to see if it’s very heavy. If it doesn’t sink, check whether the motor size is too small. If it sinks, check whether the packing is too tight, and whether the bolts around the cylinder block are not tightened evenly, resulting in the cylinder block tilting and increasing the resistance faced by the piston Another approach is to disassemble the pump body to visually check for issues, such as signs of wear.
“Our previous ones could also start with a very low pump frequency; could it be that the motor used was too small and did not have enough torque? Did you replace the motor yourself? It needs to be calculated. From Android client From Android client From Android client From Android client From Android client
Operation is normal after the drain valve is opened – excessive resistance in the normal circuit (or blockage present)