Circuit voltage regulator monitor

• US 6,118,256 A
• Filed: 08/03/1999
• Issued: 09/12/2000
• Est. Priority Date: 08/03/1999
• Status: Expired due to Fees

• Current Assignee: Emerson Electric Company
• Original Assignee: Emerson Electric Company
• Inventors: Wilson, Glenn E.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): LUK, LAWRENCE W
• Application Number:
  US09/365,921
• Time in Patent Office: 406 Days
• Field of Search: 320/166, 320/167, 363/60, 363/95
• US Class Current: 320/166
• CPC Class Codes: H02H 9/042 comprising means to limit the absorbed power or indicate damaged over-voltage protection device

Abstract

A method and apparatus for monitoring the integrity of a voltage regulating device. The voltage regulating device is coupled to a line receiving alternative current power. During normal operation of the voltage regulating device, the method and apparatus includes the use at least one capacitor that is either being charged or discharged on a repetitive basis. The voltage of the capacitor is assessed to determine whether the capacitor is charging or discharging and, thus, whether the voltage regulating device has failed.

Claims

1. A method for determining whether a voltage regulating protection device that is coupled to a line receiving alternate current power has failed, the method comprising the steps of:

a) providing at least one switching element;

b) connecting the at least one switching element in parallel with the voltage regulating protection device;

c) providing at least one capacitor;

d) connecting the at least one capacitor in parallel with the at least one switching element;

e) providing a voltage source to charge the at least one capacitor;

f) during normal operation of the voltage regulating protection device, discharging the at least one capacitor on a repetitive basis through a variable conductive current path, the variable conductive current path being rendered conductive through the application of sufficient power to the at least one switching element, the at least one switching element being unable to receive the sufficient power when;

(i) the voltage regulating protection device is conductive;

or (ii) the voltage regulating protection device has failed; and

g) assessing the voltage of the at least one capacitor to determine whether the at least one capacitor is discharging throughout the current path and, thus, whether the voltage regulating protection device has failed.

2. The method of claim 1 wherein the step of assessing the voltage of the at least one capacitor includes the steps of:

providing a light emitting device that receives current, and thus emits visible light, when the charge of the at least one capacitor is below a threshold value and that does not receive any significant current, and thus does not emit such light, when the at least one capacitor is charged above the threshold value; and

monitoring the light emitting device to determine the operational status of the voltage regulating protection device.

3. The method of claim 1 wherein the voltage regulating protection device is a metal oxide varistor.

4. The method of claim 1 wherein the at least one switching element is a opto-isolator.

5. A method for determining whether a first or second voltage regulating protection device that is coupled to a line receiving alternate current power has failed, the method comprising the steps of:

a) connecting the first voltage regulating protection device in series with the second voltage regulating protection device;

b) providing a first and second switching element;

c) connecting the first switching element in parallel with the first voltage regulating protection device;

d) connecting the second switching element in parallel with the second voltage regulating protection device;

e) providing a first and second capacitor;

f) connecting the first capacitor in parallel with the first switching element;

g) connecting the second capacitor in parallel with the second switching element;

h) providing a voltage source to charge the first and second capacitors;

i) during normal operation of the first and second voltage regulating protection devices, discharging the first and second capacitors on a repetitive basis through at least one variable conductive current path, the at least one variable conductive current path being rendered conductive through the application of sufficient power to at least one of the first or second switching elements, the at least one of the first or second switching elements being unable to receive the sufficient power when the first or second voltage regulating protection device has failed; and

j) assessing the voltage of the first and second capacitors to determine whether the first and second capacitors are discharging throughout the at least one variable conductive current path and, thus, whether the first or second voltage regulating protection device has failed.

6. The method of claim 5 wherein the step of assessing the voltage of the first and second capacitors includes the steps of:

providing a light emitting device that receives current, and thus emits visible light, when the charge of the first and second capacitors are below a threshold value and that does not receive any significant current, and thus does not emit such light, when the first and second capacitors are charged above the threshold value; and

monitoring the light emitting device to determine the operational status of the voltage regulating protection device.

7. The method of claim 5 wherein the first and second voltage regulating protection devices are metal oxide varistors.

8. The method of claim 5 wherein the first and second switching elements are opto-isolators.

9. A method for determining whether a voltage regulating protection device that is coupled to a line receiving alternate current power has failed, the method comprising the steps of:

a) providing at least one capacitor;

b) connecting the at least one capacitor in parallel with the voltage regulating protection device;

c) during normal operation of the voltage regulating protection device, charging the at least one capacitor on a repetitive basis; and

d) assessing the voltage of the at least one capacitor to determine whether the at least one capacitor is charging and, thus, whether the voltage regulating protection device has failed.

10. The method of claim 9 wherein the step of assessing the voltage of the at least one capacitor includes the steps of:

providing a light emitting device that receives current, and thus emits visible light, when the at least one capacitor is charged above a threshold value and that does not receive any significant current, and thus does not emit such light, when the at least one capacitor is below the threshold value; and

monitoring the light emitting device to determine the operational status of the voltage regulating protection device.

11. The method of claim 9 wherein the voltage regulating protection device is a metal oxide varistor.

12. Apparatus for regulating the voltage between two lines receiving power such that the voltage differential between the two lines varies on a repeating basis, the apparatus comprising:

a) a first voltage regulating device having a first contact electrically coupled to one of the two lines;

b) a second voltage regulating device having a first contact coupled to the other of the two lines and a second contact coupled to a second contact of the first voltage regulating device;

c) the first and second voltage regulating devices being such that they are each rendered conductive whenever the voltage differential between their respective first and second contacts exceeds a threshold value;

d) a capacitor element;

e) a source of energy coupled to the capacitor; and

f) means operationally associated with the first and second voltage regulating devices and the capacitor for discharging the capacitor whenever;

(i) the first voltage regulating device is rendered conductive and there is no significant current path between the first and second contacts of the second voltage regulating device;

or (ii) the second voltage regulating device is rendered conductive and there is no significant current path between the first and second contacts of the first voltage regulating device.

13. The apparatus of claim 12 wherein the first and second voltage regulating devices are metal oxide varistors.

14. The apparatus of claim 12 wherein the means for discharging the capacitor includes at least one second switching element.

15. The apparatus of claim 14 wherein the at least one second switching element is an opto-isolator.

16. Apparatus for monitoring a first and second voltage regulator, the apparatus comprising:

a) a first capacitor coupled in parallel with the first voltage regulator;

b) a second capacitor coupled in parallel with the second voltage regulator, the first and second capacitors each having a state of charge;

c) the first voltage regulator electrically connected in series to the second voltage regulator;

d) the first and second voltage regulators coupled across an alternating current voltage having a peak voltage and a cycle;

e) the first voltage regulator having a first conductive threshold voltage less than the peak voltage of the alternating current voltage;

f) the second voltage regulator having a second conductive threshold voltage less than the peak voltage of the alternating current voltage;

g) a first current path being capable of conducting current through the first voltage regulator during a first portion of the cycle of the alternating current voltage;

h) a second current path being capable of conducting current through the second voltage regulator during a second portion of the cycle of the alternating current voltage; and

i) a third current path being capable of monitoring the state of charge of the first and second capacitors.

17. The apparatus of claim 16 wherein the first and second voltage regulators are metal oxide varistors.

18. The apparatus of claim 16 wherein the first and second conductive threshold voltages are each about 100 volts.

19. The apparatus of claim 16 wherein the third current path includes a light emitting device that receives current, and thus emits visible light, when the charge the first and second capacitors are below a threshold value and that does not receive any significant current, and thus does not emit such light, when at least one of the first or second capacitors are charged above the threshold value.

20. Apparatus for controlling the voltage across two lines that receive alternating current power, the apparatus comprising:

a) a first voltage regulator having a first input coupled to one of the two lines and a second input;

b) a second voltage regulator having a first input coupled to the other of the two lines and a second input coupled to the second input of the first voltage regulator;

c) a first current path coupled in parallel with the first voltage regulator, the first current path including a first switching element;

d) a second current path coupled in parallel with the second voltage regulator, the second current path including a second switching element; and

e) a third current path including a first capacitor, a second capacitor, and a light emitting device, the first capacitor coupled in parallel with the first switching element, the second capacitor coupled in parallel with the second switching element.

21. The apparatus of claim 20 wherein the first and second voltage regulators are metal oxide varistors.

22. The apparatus of claim 20 wherein the first and second switching elements are an opto-isolator.

23. The apparatus of claim 20 wherein the light emitting device receives current, and thus emits visible light, when the charge the first and second capacitors are below a threshold value and that does not receive any significant current, and thus does not emit such light, when at least one of the first or second capacitors are charged above the threshold value.

24. The apparatus of claim 20 wherein the first and second current paths include at least one buffer element.

25. Apparatus for regulating the voltage between two lines receiving power such that the voltage differential between the two lines varies on a repeating basis, the apparatus comprising:

a) a first voltage regulating device having a first contact electrically coupled to one of the two lines;

b) a second voltage regulating device having a first contact coupled to the other of the two lines and a second contact coupled to a second contact of the first voltage regulating device;

c) the first and second voltage regulating devices being such that they are each rendered conductive whenever the voltage differential between their respective first and second contacts exceeds a threshold value;

d) at first capacitor element electrically connected in parallel to the first voltage regulating device;

e) a second capacitor element electrically connected in parallel to the second voltage regulating device;

f) during normal operations, means for charging the first capacitor element whenever the second voltage regulating device is rendered conductive and there is no significant current path between the first and second contacts of the first voltage regulating device;

g) during normal operations, means for charging the second capacitor element whenever the first voltage regulating device is rendered conductive and there is no significant current path between the first and second contacts of the second voltage regulating device;

h) means for assessing voltage across the first and second capacitor elements to determine whether the first and second capacitor elements are charging and, thus, whether the first or second voltage regulating device has failed.

26. The apparatus of claim 25 wherein the first and second voltage regulating devices are metal oxide varistors.

27. The apparatus of claim 25 wherein the means for assessing voltage across the first and second capacitor elements includes a light emitting device that receives current, and thus emits visible light, when the charge of the first and second capacitor elements are charged above a threshold value and that does not receive any significant current, and thus does not emit such light, when at least one of the first or second capacitor elements are below a threshold value.