(Urgent) Analysis of the reasons for a single-stage centrifugal pump shutting down immediately upon startup
Thread Content
There is an ordinary centrifugal pump in the factory that shuts down immediately upon startup. The motor works fine when tested individually (the bearings have been replaced with new ones), and the pump’s components also have new bearings; the runout of the shaft is 0.13 mm, and the diameter of the ring gear is 110 mm. Due to previous friction, the gap in the ring gear is now around 0.60 mm after repairs. Similar problems have occurred before, and replacing the ring gear resolved them, but I don’t think it has a significant impact. I would appreciate it if experienced colleagues could help analyze what might be causing the pump to shut down upon startup. Additionally, if the gap in the ring gear is too large, does this increase or decrease the motor’s current?
The reason for the vehicle jumping out was excessive load; check for play!
If turning the pump shaft is easy, it is recommended to start by checking the electrical aspects, such as whether the starting current exceeds the set starting trip current, and whether there are any issues with the protective components like relays and fuses. After ruling out electrical issues, check the pump.
The gap between the mouth ring is small, the radial runout is large; friction occurs at the mouth ring, resulting in high current and motor tripping
This kind of situation upstairs has also been encountered with the feed pump in the unit’s clarification tank; sometimes the pump rotated normally, while at other times there was a slight amount of friction. As soon as the centrifugal pump started operating, the current level became too high and the pump shut down. After maintenance work was carried out, it was found that the reason was indeed as mentioned above – the pump rotated normally yet still shut down, and this phenomenon is likely related to the significant radial movement mentioned earlier.
When the motor is tested separately, there are no problems; therefore, the main cause is either an excessive load on the pump or an electrical fault. First, check whether the pipeline configuration meets the required standards, and also verify if there is any friction in the pump’s transmission and rotating parts.
The motor problem should be ruled out; it’s likely an issue with the ring gap.
What is the diameter of your pump shaft? The value of 0.13 for the fluctuation exceeds the standard ；
Is the mouth ring in the correct position inside and outside the bearing?
1. Is the turntable operating smoothly, with no sticking or abnormal noises?； 2. Is the current setting of the thermal relay normal? ； 3. Is there a short circuit in the electrical components? ； 4. Check the operating current. It’s likely due to an electrical issue.
Is the 0.6 gap for your mouth ring the total gap or the gap on one side? If it’s the gap on one side, then it’s quite large. We’ve encountered this issue a few times before: when the mouth ring corrodes, the gap increases, and adjustments need to be made during startup; once the mouth ring is replaced, the problem is resolved. ；