Method of operating a safety vacuum release system

• US 8,602,743 B2
• Filed: 01/13/2012
• Issued: 12/10/2013
• 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:
  US13/350,167
• Publication Number:
  US 20120107140A1
• Time in Patent Office: 697 Days
• Field of Search: 417/26, 417/44.11, 417/45, 417/53, 450/9, 318/430, 318/432, 318/434, 318/400.21, 318/400.22, 318/490
• 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 variable speed motor, the method comprising:

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

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

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;

identifying a dead head condition if the absolute counter value exceeds an absolute counter threshold value; and

triggering the safety vacuum release system when the dead head condition is identified in order to shut down the pump substantially immediately.

2. The method of claim 1 and further comprising:

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.

3. The method of claim 2 and further comprising:

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.

4. The method of claim 3 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.

5. The method of claim 3 wherein the actual power consumption is filtered for about 2.5 seconds.

6. The method of claim 3 wherein the absolute power variation is updated about every 20 milliseconds to provide dynamic suction blockage detection.

7. The method of claim 3 and further comprising calculating a relative power consumption by dividing the absolute power variation by the current power consumption.

8. The method of claim 1 wherein the absolute counter threshold value is 10.

9. The method of claim 1 and further comprising restarting the pump after a time period has elapsed.

10. The method of claim 1 and further comprising preventing the pump from being restarted if the dead head condition is identified again.

11. The method of claim 2 wherein the dynamic counter threshold value is 15.