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EP-4339990-B1 - SURGE PROTECTIVE DEVICES

EP4339990B1EP 4339990 B1EP4339990 B1EP 4339990B1EP-4339990-B1

Inventors

  • Topcagic, Zumret
  • ROZMAN, Robert
  • KOURAKOS, VASILEIOS

Dates

Publication Date
20260506
Application Date
20230901

Claims (17)

  1. A surge protective device (1200) comprising: a first electrical terminal (1204A); a second electrical terminal (1206A); and an overvoltage protection circuit (1210) connected between the first electrical terminal and the second electrical terminal, the overvoltage protection circuit including: a spark gap assembly (1220) between the first electrical terminal and the second electrical terminal, the spark gap assembly including: a first spark gap, SG, electrode (1224) and a second SG electrode (1226) defining a spark gap (1230) therebetween; and a trigger circuit (1250) operative to ignite a main electric arc (AM) between the first and second SG electrodes across the spark gap; wherein the trigger circuit (1250) includes: a groove (1229) defined in the second SG electrode (1226); and a trigger member (1254) disposed in the groove, wherein the trigger member is operative to assist formation of a trigger arc (AT); characterised in that : the trigger circuit includes a trigger electrode (1258) interposed between the trigger member (1254) and the first SG electrode (1224); the trigger electrode (1258) electrically connects the trigger member (1254) to the first electrical terminal (1204A) in electrical parallel with the first SG electrode (1224); the first SG electrode (1224), the second SG electrode (1226) and the trigger electrode (1258) define: a first trigger spark gap (1234A) between the second SG electrode (1226) and the trigger electrode (1258); and a second trigger spark gap (1234B) between the trigger electrode (1258) and the first SG electrode (1224); and the spark gap assembly is configured to, in response to a surge impulse current, initiate a first trigger arc (AT1) across the first trigger spark gap (1234A) and thereafter a second trigger arc (AT2) across the second trigger spark gap (1234B).
  2. The surge protective device of Claim 1 wherein the trigger member (1254) is a semiconductive trigger member.
  3. The surge protective device of Claim 2 wherein the semiconductive trigger member is formed of a semiconductive ceramic.
  4. The surge protective device of any preceding Claim wherein the trigger circuit (1250) includes a trigger varistor (1268), a trigger gas discharge tube (1267), and/or a trigger resistive element in electrical series with the trigger member (1254) and in electrical parallel with the spark gap (1230).
  5. The surge protective device of any preceding Claim wherein the trigger member (1254) is in electrical contact with the trigger electrode (1258) and with the second SG electrode (1226).
  6. The surge protective device of Claim 5 wherein the trigger circuit (1250) includes a trigger varistor (1268), a trigger gas discharge tube (1267), and/or a trigger resistive element in electrical series with the trigger electrode (1258) and in electrical parallel with the first SG electrode (1224).
  7. The surge protective device of any preceding Claim wherein the spark gap assembly (1220) is a horn spark gap assembly.
  8. The surge protective device of Claim 7 wherein: the trigger member (1254) is located at a first end (1230A) of the spark gap (1230); and the spark gap assembly (1220) includes an arc chute (1240) located at an opposing second end (1230B) of the spark gap.
  9. The surge protective device of any preceding Claim including an active voltage-switching/limiting component in electrical series with the spark gap assembly.
  10. The surge protective device of Claim 9 wherein the active voltage-switching/limiting component includes a varistor or a gas discharge tube.
  11. The surge protective device of any preceding Claim wherein the trigger circuit has a trigger threshold flashover voltage for initiating electrical flashover between the first and second SG electrodes (1224, 1226) that is less than a threshold flashover voltage that would initiate electrical flashover between the first and second SG electrodes in the absence of the trigger circuit.
  12. The surge protective device of any preceding Claim wherein: the surge protective device is a surge protective device module including a spark gap module housing (1202); and the spark gap assembly (1220) is disposed in the spark gap module housing
  13. The surge protective device of Claim 12 wherein: the trigger member (1254) is located at a first end (1230A) of the spark gap; and the spark gap module housing includes an arc gas recirculation channel (1202G) configured to direct a flow (F) of arc gas from a second end (1230B) of the spark gap opposite the first end of the spark gap to an ignition region (1232I) of the spark gap adjacent the trigger member.
  14. The surge protective device of Claim 12 or Claim 13 wherein the spark gap module housing includes an intake port (1202A) configured to direct a flow of ambient air into an ignition region (1232I) of the spark gap adjacent the trigger member (1254).
  15. The surge protective device of any preceding Claim wherein: the spark gap assembly (1220) is a horn spark gap assembly; the spark gap assembly includes an arc chute (1240); the arc chute includes a set (1243) of deion plates including: a plurality of first deion plates (1242A) each having a first slot (1245A) having a first profile; and a plurality of second deion plates (1242B) each having a second slot (1245B) having a second profile different than the first profile; and the first and second deion plates are arranged in spaced apart relation and in alternating series along a chute axis such that the first and second deion plates define a series of arc chute spark gaps extending along the chute axis.
  16. The surge protective device of Claim 1 wherein: the overvoltage protection circuit (1210) includes an active voltage-switching/limiting component; the spark gap assembly () is in electrical series with the active voltage-switching/limiting component between the first electrical terminal and the second electrical terminal; the spark gap assembly is a horn spark gap assembly; and the spark gap assembly includes an arc chute (1240).
  17. The surge protective device of Claim 1 wherein: the spark gap (1230) includes: an ignition region (1232I); and a trigger region (1232T) including the first trigger spark gap (1234A) and the second trigger spark gap (1234B) and located between the trigger member (1254) and the ignition region (12321); the groove (1229) includes a base wall (1229A); and the base wall (1229A) slopes outwardly relative to the spark gap (1230) at an angle (A12) in a direction toward the ignition region (12321).

Description

Field The present invention relates to surge protective devices (SPDs). Background Frequently, excessive voltage or current is applied across or through service lines that deliver power to residences and commercial and institutional facilities. Such excess voltage or current spikes (transient overvoltages and surge currents) may result from lightning strikes, for example. The above events may be of particular concern in telecommunications distribution centers, hospitals and other facilities where equipment damage caused by overvoltages and/or current surges is not acceptable and resulting downtime may be very costly. Typically, sensitive electronic equipment may be protected against transient overvoltages and surge currents using surge protective devices (SPDs). For example, an overvoltage protection device may be installed at a power input of equipment to be protected, which is typically protected against overcurrents when it fails. Typical failure mode of an SPD is a short circuit. The overcurrent protection typically used is a combination of an internal thermal disconnector to protect the SPD from overheating due to increased leakage currents and an external fuse to protect the SPD from higher fault currents. Different SPD technologies may avoid the use of the internal thermal disconnector because, in the event of failure, they change their operation mode to a low ohmic resistance. SPDs may use one or more active voltage switching/limiting components, such as a varistor or gas discharge tube, to provide overvoltage protection. These active voltage switching/limiting components may degrade at a rapid pace as they approach the end of their operational lifespans, which may result in their exhibiting continuous short circuit behavior. An example of a voltage-limiting device is given in FR 1052741 (Ledoux), which has a resistance, e.g. a semiconductor, partly bridging the spark gap. Summary According to the invention, there is provided a surge protective device according to claim 1, which includes a first electrical terminal, a second electrical terminal, and an overvoltage protection circuit connected between the first electrical terminal and the second electrical terminal. The overvoltage protection circuit includes a spark gap assembly between the first electrical terminal and the second electrical terminal. The spark gap assembly includes a first spark gap (SG) electrode and a second SG electrode defining a spark gap therebetween, and a trigger circuit operative to ignite a main electric arc between the first and second SG electrodes across the spark gap. The trigger circuit includes a groove defined in the second SG electrode, and a trigger member disposed in the groove. The trigger member is operative to assist formation of a trigger arc. The trigger circuit includes a trigger electrode interposed between the trigger member and the first SG electrode; the trigger electrode electrically connects the trigger member to the first electrical terminal in electrical parallel with the first SG electrode; the first SG electrode, the second SG electrode and the trigger electrode define: a first trigger spark gap between the second SG electrode and the trigger electrode; and a second trigger spark gap between the trigger electrode and the first SG electrode; and the spark gap assembly is configured to, in response to a surge impulse current, initiate a first trigger arc across the first trigger spark gap and thereafter a second trigger arc across the second trigger spark gap. According to some embodiments, the trigger member is a semiconductive trigger member. In some embodiments, the semiconductive trigger member is formed of a semiconductive ceramic. In some embodiments, the semiconductive ceramic is selected from the group consisting of zinc oxide, barium titanate, and silicon carbide. According to some embodiments, the trigger circuit includes a trigger varistor, a trigger gas discharge tube, and/or a trigger resistive element in electrical series with the trigger member and in electrical parallel with the spark gap. According to some embodiments, the trigger electrode is in electrical contact with the trigger member and with the second SG electrode. In some embodiments, the trigger circuit includes a trigger varistor, a trigger gas discharge tube, and/or a trigger resistive element in electrical series with the trigger electrode and in electrical parallel with the first SG electrode. According to some embodiments, the spark gap assembly is a horn spark gap assembly. In some embodiments, the trigger member is located at a first end of the spark gap, and the spark gap assembly includes an arc chute located at an opposing second end of the spark gap. According to some embodiments, the surge protective device of Claim 1 includes an active voltage-switching/limiting component in electrical series with the spark gap assembly. In some embodiments, the active voltage-switching/limiting component includes a varistor o