Reasons for high current at the moment of starting a centrifugal pump
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What is the reason for the high current when a centrifugal pump starts? I seek advice from experts
The starting current of the motor is already quite high
To use an inappropriate analogy, when a motor starts, it’s like a short-circuit current, so the current level is very high
The starting current of the motor is 5-7 times the rated current
A high starting current is normal; however, if the starting current is abnormally high, there are likely the following reasons (the possibility of individual factors causing this is extremely low): 1. Frictional jams within the pump’s rotating components; 2. Excessively high rotational inertia of the rotor; 3. Differences in startup behavior between switches and valves in certain types of pumps; 4. Highly viscous media; 5. Excessive residual axial force; 6. Inappropriate selection of motor power; 7. Pump operating in reverse; 8. Motor failure; 9. Electrical system failures
A high starting current in a device is akin to providing it with an initial driving force; this initial force has to overcome various external factors in order for the device to start functioning. Once it reaches a certain operating state, the current becomes normal – and this is why the motor has a high starting current.
A high starting current is normal. If the outlet pressure is normal after startup and the current remains high when the pump is operating normally, then there is a problem
Before starting, it is necessary to overcome the huge friction between the rotor, the casing, and the medium!
Thank you all for the active discussions. When it comes to studying induced electromotive force and inductive reactance, I encounter difficulties; I think the issue lies right here, and once this is understood, things will be fine. What impact does the generation of induced electromotive force have on the operation of the motor? What are the conditions for the generation of motor inductive reactance? What is the impact of the generation of inductive reactance on the operation of a motor? What are the conditions for its occurrence? It would be best to use a formula plus a textual explanation; I’m begging experts!
Soft start and variable-frequency start can be used to reduce the starting current
When the motor starts, the rotor changes from a stationary state to a rotating state, which requires a great deal of torque； When a centrifugal pump starts, it operates under load due to the presence of fluid, which results in a higher current.