OVERVOLTAGE PROTECTION DEVICE WITH IMPROVED LEAKAGE-CURRENT-INTERRUPTING CAPACITY

• US 20090021881A1
• Filed: 07/25/2001
• Published: 01/22/2009
• Est. Priority Date: 07/26/2004
• Status: Abandoned Application

• Current Assignee: Abb France (ABB Ltd.)
• Original Assignee: Abb France (ABB Ltd.)
• Inventors: Crevenat, Vincent Andre Lucien
• Application Number:
  US11/572,777
• Publication Number:
  US 20090021881A1
• Time in Patent Office: Days
• US Class Current: 361/111
• CPC Class Codes: H01T 2/02 comprising a trigger electrode or an auxiliary spark gap
• CPC Class Codes: H02H 9/06 using spark-gap arresters

Abstract

A device for protecting an electrical installation (2) against overvoltages, the device having a main spark-gap (E1) and a pre-triggering circuit (10) connected to the main spark-gap (E1) to control the firing of the main spark-gap in the event of any overvoltage. The pre-triggering circuit (10) has at least one voltage-interrupting element (G) which, in the off state, prevents current from passing through the pre-triggering circuit (10), so that, in the absence of an overvoltage, the leakage current consumed by the pre-triggering circuit (10) is essentially zero.

Claims

1. A device for protecting an electrical installation against overvoltage, in particular transient overvoltages due to lightning strikes, wherein the device bypasses the electrical installation, the device comprising:

a) a main spark gap, and

b) a pre-triggering circuit that is sensitive to overvoltage, the pre-triggering circuit bypassing the electrical installation and connecting to the main spark gap so that the pre-triggering circuit controls the striking of the arc in the main spark gap when an overvoltage occurs,

wherein the pre-trigger circuit comprises at least one voltage cut-off element specifically designed to change state when the voltage at the terminals exceeds a pre-determined threshold value, from a non-conductive state, in which the voltage cut-off element prevents current from circulating, to a conductive state, in which the voltage cut-off element permits current to circulate, wherein the voltage cut-off element prevents, in the non-conductive state, the current from circulating in the pre-trigger circuit so that in the absence of an overvoltage, the leakage current consumed by the pre-trigger circuit is substantially nil.

2. The device of claim 1, wherein the pre-triggering circuit comprises a triggering transformer equipped with a primary coil and a secondary coil wherein the secondary coil connects to the main spark gap so that the voltage induced at the terminals of the secondary coil causes the main spark gap to arc when the primary coil is crossed by a current.

3. The device of claim 2, wherein the main spark gap comprises at least two main electrodes;

and the secondary coil is connected to one of the main electrodes.

4. The device of claim 2, wherein the main spark gap comprises a pre-triggering element to which the secondary coil is connected.

5. The device of claim 2, wherein the pre-triggering circuit comprises a branch connected in parallel to the main spark gap, the branch further comprising the primary coil and the voltage cut-off element connected in series to the primary coil and specifically positioned so that the leakage current in the entire pre-triggering circuit is substantially nil in the absence of a voltage surge.

6. The device of claim 1, wherein the pre-triggering circuit comprises at least one voltage limiting element connected in series to the voltage cut-off element.

7. The device of claim 6, wherein the voltage limiting element is formed by a varistor.

8. The device of claim 2, wherein the pre-triggering circuit comprises at least one additional voltage limiting element of the varistor type connected in parallel to the primary coil.

9. The device of claim 1, wherein the pre-triggering circuit comprises at least one component for protecting against overvoltage connected in series to the voltage cut-off element.

10. The device of claim 9, wherein the component for protecting against overvoltage is a thermal fuse.

11. The device of claim 7, wherein the thermal fuse is physically positioned against the variable resistor.

12. The device of claim 2, wherein the pre-triggering circuit comprises two voltage cut-off elements connected in series with the primary coil and positioned electrically on either side of the primary coil so that the transformer is isolated from the rest of the components of the pre-triggering circuit.

13. The device of claim 12, wherein the pre-triggering circuit comprises two voltage limiting elements connected in series with the two voltage cut-off elements.

14. The device of claim 10, wherein the two voltage limiting elements are formed by varistors and the thermal fuse is positioned between the two voltage limiting elements and is in physical contact with the two voltage limiting elements.

15. The device of claim 1, wherein the voltage cut-off element is formed by a spark gap.

16. The device of claim 3, wherein the pre-triggering circuit comprises a branch connected in parallel to the main spark gap, the branch further comprising the primary coil and the voltage cut-off element connected in series to the primary coil and specifically positioned so that the leakage current in the entire pre-triggering circuit is substantially nil in the absence of a voltage surge.

17. The device of claim 4, wherein the pre-triggering circuit comprises a branch connected in parallel to the main spark gap, the branch further comprising the primary coil and the voltage cut-off element connected in series to the primary coil and specifically positioned so that the leakage current in the entire pre-triggering circuit is substantially nil in the absence of a voltage surge.

18. The device of claim 10, wherein the thermal fuse is physically positioned against the variable resistor.

19. The device of claim 13, wherein the two voltage limiting elements are formed by varistors and the thermal fuse is positioned between the two voltage limiting elements and is in physical contact with the two voltage limiting elements.