What are the hazards of restarting a centrifugal pump without shutting off its outlet after it stops operating due to shaking?
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Is the risk lower if the pump is started without coming to a complete stop first?
The starting current is too high, causing the motor to trip.
We experienced a power fluctuation; the motor stopped running. Once power was restored, we started the pump right away without closing the outlet valve first. There will definitely be harm.
There are certainly risks, but you should understand the principle of choosing the lesser of two evils.
The pump is still running in forward direction; there should be an outlet check valve, which should prevent the pump’s starting current from being too high and causing a trip. However, during power fluctuations, the grid load changes significantly, and everyone in the workshops acts immediately as a result, leading to even greater fluctuations in the grid voltage and an increased risk of the pump running in reverse. Without an outlet check valve, the pump might be running empty, and starting it right away may not result in any liquid being pumped out. This is especially true during periods of power fluctuations when things are busy; if the pump runs empty for a long time, it becomes clear at that point what the problem is
Basic operation: If it can start on its own, do so; otherwise, start the backup pump.
In chemical plants, pump tripping is a common occurrence, with various causes, mainly including the following aspects: 1. Issues with the equipment itself: damaged bearings, damaged motor insulation, overheating, etc. 2. Operational problems: blockages, excessive outlet pressure, violations of operating procedures. 3. Electrical problems: wiring and grounding issues, missing phases, lack of soft start functionality, etc. 4. External factors: power outage, lightning-induced tripping
Generally, the following precautions should be observed: 1. Ensure the power grid is stable before starting the relevant equipment； 2. If there is no operating condition for starting the equipment with the valve open during selection, it is best not to start it with the valve open ； 3. When starting with the valve open, if the system pressure is low, the motor will experience overcurrent and the torque will exceed the allowable value; in severe cases, shaft breakage can occur.
The fitter told us that starting the pump right after it came to a stop would cause cavitation and lead to overheating; it seemed like he was talking nonsense