Why is the current of the centrifugal pump high?
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I recently encountered a situation where, no matter how small the outlet opening of the centrifugal pump was, the current remained very close to the rated current. The current is twice as high as that of other backup pumps. I checked it myself and asked around; some said the motor was too small, while others said the impeller was stuck. There was a problem with the motor; this situation didn’t exist before. The impeller is stuck; there should be an abnormal noise! So I am still a bit puzzled by these explanations. Please help analyze it, thank you all, fellow sailors
First, check the current when the motor is running idle. Impeller friction is also a possibility
It’s probably a problem with the motor; check if there is a missing phase.
It is possible to check the gaps between various components. I have encountered such situations with horizontal high-speed pumps, where an excessive gap between the impeller and the rear partition led to flow loss; after replacing the partition, the problem was resolved
It is possible to check the gaps between various components. I have encountered such situations with horizontal high-speed pumps, where an excessive gap between the impeller and the rear partition led to flow loss; after replacing the partition, the problem was resolved
If the motor is missing a phase, it should not be able to start. Other things to check include the bearing temperature and the pump body temperature (if there is friction in the impeller, this will generally show up in the pump body temperature), as well as whether there are any unusual noises inside the pump. It’s also necessary to consider the possibility of false current readings.
It’s one of the most common problems in the chemical industry: is the inlet filter clogged, is the flow rate too low, or has it been emptied? First, check the filter (it is the main suspect), then test the motor separately, as the problems with the motor itself need to be ruled out before considering issues with the pump. If the motor works fine when tested individually, what are the alignment parameters? What does manual turning of the shaft look like? Is there any lag? When operating under load, what are the vibration values of the bearings at the front and rear of the pump? If everything is normal, disassemble the pump and check the clearance at the impeller’s mouth ring (this is where problems are most likely to occur). Check for any 5-point runout of the shaft and ensure proper dynamic balancing. If everything remains normal even after disassembling the pump, then it’s a design issue. The last solution is to machine the impeller slightly in order to reduce the flow rate. I’ve encountered this in practice: the flow rate of the pump is matched to that of the motor in a 1-to-1 ratio, rather than the **specified 1-to-1.2 or 1.5 ratio; I can’t remember which it is. . . The last option if you don’t want to replace the motor is to use a vehicle impeller
1. The impeller clearance is small, resulting in friction； 2. Wear of the pump inlet ring, resulting in internal fluid circulation ； 3. Debris enters the pump, affecting the operation of the impeller ； 4. The cross-line valves at the pump inlet and outlet are not closed or there is leakage
The motor is small; the medium density is high; the inlet filter is clogged, causing overcurrent; the flow rate is too high; the pump and motor are not well-matched
Unconnect the coupling and run the motor under no-load conditions to check the current value in that state. First, we need to determine whether it’s a problem with the motor. After the centrifugal pump is shut down, check if there are any issues when trying to turn the shaft manually. There are many reasons for lubrication-related problems; excessive current is usually caused by degraded grease, which leads to bearing damage and thus an increase in current levels