Pump overcurrent issue
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This post was last edited by my_love_jh on 2020-2-14 at 19:35. Everyone, our facility has a directly-connected horizontal single-stage centrifugal pump with a standard flow rate of 600 m3/h, a head of 44 m, and a motor power of 110 kW. Currently, after the pump is started normally, the flow rate is only around 200–300 m3/h, and the outlet pressure is approximately 0.6 Mpa; at this point, the motor triggers an overcurrent alarm and shuts down. The vibration of the pump is normal, remaining below 2 mm/S regardless of the measurement location. The only issue is that the temperature of the shaft near the dust seal on the side of the impeller where the motor is located is relatively high, as shown in the thermal imaging image below. Please help analyze the reasons why the pump does not reach its rated flow rate and causes an overcurrent issue
Is the axial or radial force too large? What model of pump?
KQW300/400A-110/4N-VI
This specification should feature a double volute structure; looking at the pump’s outlet, there is a rib-like element in the middle
With such a large diameter, why use a single volute? The radial force increases both at low and high flow rates
I now doubt whether, during pump operation, the impeller came into contact with the mouth ring due to axial forces
The equipment must be in a state with relatively suitable normal operating conditions. If such problems arise now, it’s time for a disassembly inspection. If there are no issues, when it is restarted for use, it should operate as closely as possible within the designed parameters.
I think from the start, when you chose the pumps, the prototype wasn’t selected properly. Also, is the working medium just water?
It’s better to use a double-suction version, as it’s more stable. In the case of such excessive current occurring, it’s best to first check whether the current and flow rates are accurate. If that’s accurate, then it must be a problem with the pump; friction is likely causing an increase in current!