Pump Control Method for Clogging Clearance and Water Hammer Prevention
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Solution Overview
Problem
Current pump control methods are inefficient in handling clogging issues, leading to increased power consumption, potential damage to the pump and control unit, and the need for costly emergency service interventions due to direct motor stopping causing water hammer and overstraining of components.
Innovation Solution
A method that stops the motor at a lower torque than normal operation, allowing for controlled ramping down and subsequent unfastening attempts with greater torque to avoid wedging and reduce emergency turnouts, using predetermined limits and directional changes to manage clogging effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor is stopped directly when clogging is detected, then the pump can be quickly cleared, but water hammer occurs and the impeller may be loosened or the drive shaft damaged
Solution Approach 1:
The control unit performs preliminary action by initiating a controlled ramping down of the motor speed before stopping the motor completely. This gradual deceleration prevents water hammer and mechanical damage while still enabling timely clogging clearance. The system prepares the pump for shutdown in advance rather than abrupt stopping.
2Reliability
If a long predetermined ramping down is performed during strained operation condition, then water hammer is avoided, but the load on the pump increases when a large object is wedged, forcing the impeller to rotate and wedging the object harder
Solution Approach 1:
The control unit dynamically adjusts the ramping down time based on the detected operation condition. During detrimental conditions with wedged objects, the system uses a shorter ramping down time to avoid overloading the pump, while during normal strained operation, it uses a longer ramping down time to prevent water hammer. This dynamic adaptation resolves the contradiction between protection and mechanical load.
Solution Approach 2:
The control unit changes the parameter of ramping down time based on the detected operational state. By monitoring operational parameters, the system adjusts the deceleration profile to match the actual pump condition, using shorter times for detrimental conditions and longer times for normal strained operation, thereby resolving the contradiction between water hammer protection and mechanical load reduction.
3Reliability
If safety systems trigger before equipment damage occurs, then equipment is protected, but emergency service interventions are required which are costly and cause pump idle time
Solution Approach 1:
The pump arrangement performs self-service by automatically detecting clogging conditions and executing appropriate clearance procedures through the control unit. The system handles minor clogging events autonomously without requiring external service intervention, thereby maintaining pump availability while still protecting equipment through intelligent monitoring and controlled responses.
Data Source
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AI summary
The invention relates to a method for controlling a pump arrangement upon clogging of a pump, the pump arrangement comprising a pump and a control unit, the pump comprising a motor, and the control unit being arranged to drive said motor, the motor during operation being associated with an operational parameter from which the torque of the motor may be derived, said operational parameter has a normal value PN during normal operation of the motor in a first direction. The method being characterized by the steps of driving the motor in a first direction by means of the control unit, stopping the motor if a real value P of the operational parameter exceed a predetermined clogging limit PI, where PI ≥ 1,05*PN, driving the motor in a the first direction opposite second direction a predetermined flushing time TR by means of the control unit, and stopping the motor if the absolute value of the real value P of the operational parameter during the flushing time TR exceed the absolute value of a first unfastening limit PL1, where | PL1I ≥ 1, 1*PI, otherwise stopping the motor after said flushing time TR and returning to normal operation.