Setting of the low current protection for centrifugal pumps
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Some centrifugal pumps are equipped with low-current protection; it is also referred to as low-power protection, and this applies to centrifugal pumps that do not have variable frequency functionality. I have always wanted to determine what rules should be followed for setting the low-current protection on centrifugal pumps – for example, should the low-current protection be set based on the pump’s no-load current? Also, should the current setting for low-current protection necessarily be lower than the current when the pump’s outlet is closed, that is, during operation under choked conditions?
We just added it recently to protect the canned pump, preventing the isolation sleeve from being worn out due to vacuum conditions. The setting should be higher than the crushing current, right?
For shielded pumps, I think they are used to protect the sliding bearings and prevent dry friction
Low current protection is intended to prevent dry burning and damage to the mechanical seal
The operating current of the pump during idling should be lower than that during operation under load; aside from the power loss caused by friction, there should be no other types of losses during idling； During steady-state operation, although the flow rate is 0, there is still a head pressure.