Method of operating a safety vacuum release system

• US 8,313,306 B2
• Filed: 10/02/2009
• Issued: 11/20/2012
• Est. Priority Date: 10/06/2008
• Status: Active Grant

• Current Assignee: Danfoss Power Electronics A/S (Danfoss A/S), Pentair Water Pool And Spa Incorporated (Pentair Plc (Ireland))
• Original Assignee: Danfoss Low Power Drives, Pentair Water Pool And Spa Incorporated (Pentair Plc (Ireland))
• Inventors: Stiles, Robert W. Jr., Berthelsen, Lars Hoffmann
• Primary Examiner(s): FREAY, CHARLES GRANT
• Application Number:
  US12/572,774
• Publication Number:
  US 20100092308A1
• Time in Patent Office: 1,145 Days
• Field of Search: 417/26, 417/44.11, 417/45, 417/53, 450/9
• US Class Current: 417/26
• CPC Class Codes: E04H 4/1209 Treatment of water for swimming pools filters B01D
• CPC Class Codes: E04H 4/1245 Recirculating pumps for swimming pool water
• CPC Class Codes: E04H 4/16 specially adapted for cleaning
• CPC Class Codes: F04B 2203/0201 Current
• CPC Class Codes: F04B 2203/0202 Voltage
• CPC Class Codes: F04B 49/065 and making use of computers
• CPC Class Codes: F04B 49/10 Other safety measures
• CPC Class Codes: F04B 49/106 Responsive to pumped volume

Abstract

Embodiments of the invention provide a method of operating a safety vacuum release system (SVRS) with a controller for a pump including a motor. The method can include measuring an actual power consumption of the motor necessary to pump water and overcome losses. The method can include triggering the SVRS when a dynamic suction blockage is identified in order to shut down the pump substantially immediately. The SVRS can also be triggered when a dead head condition is identified based on the actual power consumption.

Claims

1. A method of operating a safety vacuum release system with a controller for a pump including a motor, the method comprising:

measuring an actual power consumption of the motor necessary to pump water and overcome losses;

calculating an absolute power variation based on the actual power consumption;

incrementing a dynamic counter value if the absolute power variation is negative;

calculating a relative power variation based on the actual power consumption;

identifying a dynamic suction blockage if at least one of the dynamic counter exceeds a dynamic counter threshold value and the relative power variation is below a negative threshold; and

triggering the safety vacuum release system when the dynamic suction blockage is identified in order to shut down the pump substantially immediately.

2. The method of claim 1 and further comprising:

filtering the actual power consumption with a fast low-pass filter to obtain a current power consumption;

filtering the actual power consumption with a slow low-pass filter to obtain a lagged power consumption; and

calculating the absolute power variation by subtracting the lagged power consumption from the current power consumption.

3. The method of claim 2 wherein the fast low-pass filter has a time constant of about 200 milliseconds and the slow low-pass filter has a time constant of about 1400 milliseconds.

4. The method of claim 2 wherein the actual power consumption is filtered for about 2.5 seconds.

5. The method of claim 2 wherein the absolute power variation is updated about every 20 milliseconds to provide dynamic suction blockage detection.

6. The method of claim 2 and further comprising calculating a relative power consumption by dividing the absolute power variation by the current power consumption.

7. The method of claim 2 and further comprising incrementing an absolute counter value if at least one of the actual power consumption and the current power consumption is greater than a threshold power curve.

8. The method of claim 7 and further comprising identifying a dead head condition if the absolute counter value exceeds an absolute counter threshold value.

9. The method of claim 8 wherein the absolute counter threshold value is 10.

10. The method of claim 8 and further comprising restarting the pump after a time period has elapsed.

11. The method of claim 10 and further comprising preventing the pump from being restarted if the dead head condition is identified again.

12. The method of claim 1 wherein the dynamic counter threshold value is 15.