OVERVOLTAGE PROTECTION ELEMENT MONITORING

• US 20150369856A1
• Filed: 12/28/2012
• Published: 12/24/2015
• Est. Priority Date: 12/28/2012
• Status: Abandoned Application

• Current Assignee: Abb Oy (ABB Limited)
• Original Assignee: ABBYY USA (ABBYY Software)
• Inventors: Takala, Marko, Mattlar, Harri, Khkipuro, Matti, Kentala, Tero, Rantalen, Tommi
• Application Number:
  US14/758,473
• Publication Number:
  US 20150369856A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01R 31/013 Testing passive components testing relays G01R31/3278; testing electrical windings, e.g. inductors G01R31/72
• CPC Class Codes: G01R 31/2827 Testing of electronic protection circuits testing switches G01R31/327; checking alarm systems G08B29/00; self test of summation current transformers H02H3/335
• CPC Class Codes: H01C 7/12 Overvoltage protection resistors series resistors structurally associated with spark gaps H01T1/16
• CPC Class Codes: H02H 3/05 with means for increasing reliability, e.g. redundancy arrangements for logic circuits H03K19/003
• CPC Class Codes: H02H 3/20 responsive to excess voltage

Abstract

The invention relates to a method and an arrangement for determining an end-of-life of an overvoltage protection element (2) by determining (101) a predefined voltage limit based on a nominal voltage, determining (102) a measuring voltage across switch components (5) of the switch arrangement in connection with a switch-off event, and determining (103) that the overvoltage protection element (2) has reached its end-of-life when the measuring voltage is equal to or lower than the predefined voltage limit.

Claims

1. A method for determining an end-of-life of an overvoltage protection element of a switch arrangement in an electric circuit, wherein the method comprises:

determining a predefined limit value for a variable indicating wear of an overvoltage protection element,

determining at least one of the following measuring values;

a measuring voltage across switch components of the switch arrangement in connection with a switch-off event and current through the overvoltage protection element during the switch arrangement being in a switched off state, and

determining that the overvoltage protection element has reached its end-of-life on the basis of a comparison between the predefined limit value and the determined measuring value or a derived value obtained by using the determined measuring value.

2. A method according to claim 1, wherein the overvoltage protection element has a nominal voltage, wherein the method comprises:

determining a predefined voltage limit based on the nominal voltage for the overvoltage protection element,

determining a measuring voltage across switch components of the switch arrangement in connection with a switch-off event, and

determining that the overvoltage protection element has reached its end-of-life when the measuring voltage is equal to or lower than the predefined voltage limit.

3. A method according to claim 2, wherein the overvoltage protection element comprises a varistor.

4. A method according to claim 2 or 3, wherein the predefined voltage limit is in the range of 85 to 92 percent of the nominal voltage of the overvoltage protection element.

5. A method according to claim 4, wherein the predefined voltage limit is approximately 90 percent of the nominal voltage of the overvoltage protection element.

6. A method according to any one of claims 1 to 5, wherein the electric circuit further comprises a control element and wherein the measuring value and end-of-life of the overvoltage protection element are determined in the control element.

7. A method according to claim 6, wherein the control element comprises a programmable integrated circuit.

8. A method according to any one of claims 1 to 7, wherein a graphical interface is connected to the electric circuit and the method further comprises indicating the end-of-life of the overvoltage protection element in the graphical user interface.

9. A method according to any one of claims 6 to 8, wherein the electric circuit further comprises means for measuring current in the electric circuit and memory means, wherein the predefined limit value comprises a pre-estimated total energy value the overvoltage protection element is able to absorb over time, and wherein the method further comprises

determining in the control element the energy absorbed by the overvoltage protection element on the basis of the voltage and current measurements and the pulse duration,

storing in the memory means data about the energy absorbed by the overvoltage protection element over time, and

comparing the energy absorbed by the overvoltage protection element over time and the pre-estimated total energy value and indicating, in response to the comparison, at least one of the following:

an end-of-life of the overvoltage protection element and a relation between the determined energy absorbed by the overvoltage protection element over time and the pre-estimated total energy value.

10. A method according to any one of claims 1 to 9, wherein

the predefined limit value comprises an allowed leakage current value, the measuring value comprises the current through the overvoltage protection element during the switch arrangement being in a switched off state, and wherein

determining that the overvoltage protection element has reached its end-of-life is done on the basis of the current through the overvoltage protection element during the switch arrangement being in a switched off state being equal or higher than the allowed leakage current.

11. A switch arrangement for switching an electric circuit comprising:

switch components,

overvoltage protection element having a predefined limit value for a variable indicating wear of an overvoltage protection element,

means for determining at least one of the following measuring values;

a measuring voltage across switch components of the switch arrangement in connection with a switch-off event and current through the overvoltage protection element during the switch arrangement being in a switched off state, and

means for determining an end-of-life of the overvoltage protection element in response to a comparison between the predefined limit value and the determined measuring value or a derived value obtained by using the determined measuring value.

12. A switch arrangement according to claim 11, wherein the overvoltage protection element comprises a varistor.

13. A switch arrangement according to claim 11 or 12, wherein the predefined limit value comprises a predefined voltage limit and the predefined voltage limit is in the range of 85 to 92 percent of a nominal voltage of the overvoltage protection element.

14. A switch arrangement according to claim 13, wherein the predefined voltage limit is approximately 90 percent of the nominal voltage of the overvoltage protection element.

15. A switch arrangement according to any one of claims 11 to 14, wherein the electric circuit further comprises a control element and wherein the control element is configured to determine the measuring value and the end-of-life of the overvoltage protection element.

16. A switch arrangement according to claim 15, wherein the control element comprises a programmable integrated circuit.

17. A switch arrangement according to any one of claims 11 to 16, wherein a graphical interface is connected to the electric circuit and the graphical interface is configured to indicate the end-of-life of the overvoltage protection element in the graphical user interface.