Enhanced time-based proportional control

• US 6,716,359 B1
• Filed: 08/29/2000
• Issued: 04/06/2004
• Est. Priority Date: 08/29/2000
• Status: Expired due to Fees

• Current Assignee: Evoqua Water Technologies LLC
• Original Assignee: United States Filter Corporation (Siemens AG)
• Inventors: Dennis, Richard W. II
• Primary Examiner(s): DRODGE, JOSEPH W
• Application Number:
  US09/650,456
• Time in Patent Office: 1,316 Days
• Field of Search: 210/96.1, 210/130, 210/143, 210/169, 210/198.1, 210/614, 210/662, 210/709, 210/739, 700/28, 700/33, 700/37, 700/41-43, 700/273, 706/23
• US Class Current: 210/739
• CPC Class Codes: G05D 21/02 characterised by the use of electric means

Abstract

The instant invention is a device and method for its use which includes the addition of a deviation compensation function effective to automatically adjust the offset used in time-based proportional control. Inclusion of this improvement finds particular utility in situations like public pools where daily bather load varies depending on weather and other unpredictable factors.

Claims

1. A process for time-based proportional control of chemical values in a water treatment system wherein a measured signal value is generated, comprising the steps:

selecting an offset sensitivity value; and

calculating a setpoint offset value (SOV) to determine said measured signal value;

wherein said measured signal value approximates an ideal proportional control response, and

wherein said setpoint offset value is calculated according to the formula

2. In a process for time-based proportional control of chemical values in a water treatment system wherein a measured signal value is generated, the improvement comprising:

modifying said measured signal value to be within a range defined by a particular proportional band width;

verifying that said signal value likes within a hysteresis value about a particularly defined setpoint;

measuring said signal value to confirm that said signal value is steady or retreating from said setpoint during a selected time duration;

selecting an offset sensitivity value; and

calculating a setpoint offset value (SOV) according to the formula

3. A process in accordance with claim 2 wherein:

said particular proportional band width is between about 5 and 500 mV.

4. A process in accordance with claim 2 wherein:

said particular proportional band width is between about 0.1 and 5.0 pH units.

5. A process in accordance with claim 2 wherein:

said particular proportional band width is between about 10 and 5000 microsiemens.

6. A process in accordance with claim 2 wherein:

said time base is between about 15 and 600 seconds.

7. A process in accordance with claim 2 wherein:

said selected time duration is a multiple of the time base.

8. A process in accordance with claim 2 wherein:

said hysteresis value is between about 0 and 10 mV.

9. A process in accordance with claim 2 wherein:

said hysteresis value is between about 0 and 1.0 pH units.

10. A process in accordance with claim 2 wherein:

said particular proportional band width is between about 0 and 1000 microsiemens.

11. A process in accordance with claim 2 wherein said setpoint is between about 150 and 780 mV.

12. A process in accordance with claim 2 wherein:

said setpoint is between about 2 and 12 pH units.

13. A process in accordance with claim 2 wherein:

said setpoint is between about 1000 and 4000 microsiemens.

14. A process in accordance with claim 2 wherein:

said offset sensitivity value is within the range of about 0 and 100 percent.