System and method for operating a pump
A pumping system and method for operating a pumping system including a motor coupled to a variable speed drive to drive a pump. A torque indicator corresponding to the torque presented to the drive is determined. The torque indicator may be used to detect a fault if it exceeds a baseline torque, or to detect a defective transducer, or to detect a system change by perturbing one parameter and comparing another to a predicted value.
1. A pumping system comprising: a variable frequency drive adapted to drive a pump with a motor, the variable frequency drive including a processor and a non-transitory computer readable medium having embedded therein processing instructions configured to perform a method when executed by the processor, the method including:
determining a torque indicator comprising one of torque, motor power or motor current;
determining the torque indicator during a fault calibration period to determine a baseline;
setting a fault threshold based on the baseline;
after setting the fault threshold, detecting a fault if the torque indicator exceeds the fault threshold;
reducing pump speed if the torque indicator exceeds a limit greater than the baseline but lower than the fault threshold; and
identifying a stall condition if the pump operates at the reduced speed for a predetermined time.
2. A pumping system as in claim 1 , wherein the fault threshold is between about 130% and 170% of the baseline.
3. A pumping system as in claim 1 , wherein the fault threshold is between about 140% and 160% of the baseline.
4. A pumping system as in claim 1 , wherein the torque indicator comprises a rate of change.
5. A method for operating a pumping system with a variable speed drive including a processor and a non-transitory computer readable medium having embedded therein processing instructions configured to perform the method when executed by the processor, the method comprising:
driving a motor and a pump coupled with the motor;
determining a torque indicator comprising one of torque, motor power or motor current, wherein the torque is proportional to head pressure and pump speed is proportional to flow;
determining the torque indicator during a fault calibration period after a start-up period to determine a baseline;
setting a fault threshold based on the baseline;
after setting the fault threshold, detecting a fault if the torque indicator exceeds the fault threshold; and
reducing, a pump speed responsive to detecting the fault.
6. A method as in claim 5 , wherein the fault threshold is between about 130% and 170% of the baseline.
7. A method as in claim 5 , wherein the fault threshold is between about 140% and 160% of the baseline.
8. A method as in claim 5 , wherein the torque indicator comprises a rate of change.
9. A method as in claim 5 , wherein the baseline is determined after each start-up period.
10. A method as in claim 5 , further comprising discontinuing operation of the pump upon detecting the fault.
11. A method for operating a pumping system with a variable frequency drive including a processor and a non-transitory computer readable medium having embedded therein processing instructions configured to perform the method when executed by the processor, the method comprising:
driving a motor and a pump coupled with the motor;
determining a torque indicator comprising one of torque, motor power or motor current;
determining the torque indicator during a fault calibration period to determine a baseline;
setting a fault threshold based on the baseline;
after setting the fault threshold, detecting a fault if the torque indicator exceeds the fault threshold,
wherein the torque is proportional to head pressure and pump speed is proportional to flow; and
discontinuing operation of the pump upon detecting the fault.
12. The method of claim 11 , wherein the fault threshold is between about 130% and 170% of the baseline.
13. The method of claim 11 , wherein the torque indicator comprises a rate of change.
14. The method of claim 11 , wherein determining the torque indicator during a fault calibration period is performed after every start-up period.
15. A method for operating a pumping system with a variable frequency drive including a processor and a non-transitory computer readable medium having embedded therein processing instructions configured to perform the method when executed, by the processor, the method comprising:
driving a motor and a pump coupled, with the motor;
determining a torque indicator comprising one of torque, motor power or motor current;
determining the torque indicator during a fault calibration period to determine a baseline;
setting a fault threshold based on the baseline;
after setting the fault threshold, detecting a fault if the torque indicator exceeds the fault threshold;
reducing pump speed if the torque indicator exceeds a limit greater than the baseline but lower than the fault threshold; and
identifying a stall condition if the pump operates at the reduced speed for a predetermined time.
16. The method of claim 15 , wherein the fault threshold is between about 130% and 170% of the baseline.
17. The method of claim 15 , wherein the torque indicator comprises a rate of change.
18. The method of claim 15 , wherein determining the torque indicator during a fault calibration period is performed after every start-up period.
19. A pumping system comprising: a variable frequency drive adapted to drive a pump with a motor, the variable frequency drive including a processor and a non-transitory computer readable medium having embedded therein processing instructions configured to perform a method when executed by the processor, the method including:
determining a torque indicator comprising one of torque, motor power or motor current, wherein the torque is proportional to head pressure and pump speed is proportional to flow;
determining the torque indicator during a fault calibration period to determine a baseline;
setting a fault threshold based on the baseline;
after setting the fault threshold, detecting a fault if the torque indicator exceeds the fault threshold; and
reducing a pump speed responsive to detecting the fault.
20. The pumping system of claim 19 , wherein the fault threshold is between about 130% and 170% of the baseline.
21. The pumping system of claim 20 , wherein the fault threshold is between about 140% and 160% of the baseline.
22. The pumping system of claim 19 , wherein the torque indicator comprises a rate of change.
23. The pumping system of claim 19 , wherein determining the torque indicator during a fault calibration period is performed after every start-up period.