An electrical connector provided with a varistor, and to a protection device for incorporation into an electrical connector and having a varistor comprising at least two pins including a first pin which is a live (502) or neutral (504) pin and a second pin which is an earth pin (506), the first and second pins (502, 504, 506) extending through respective apertures (512) in a varistor plate (514) which has first and second faces, wherein a first conductive layer on the first face of the varistor plate (514) connects electrically to the first pin (502, 504) and a second conductive region on the second face of the varistor plate connects electrically to the second pin (506), so that in response to an excessive voltage across the first (502, 504) and second (506) pins the varistor plate will conduct electricity between the first (502, 504) and second (506) pins. The arrangement can easily be adopted in connectors conforming to existing standards, such as existing mains electrical plugs (500).

The invention relates to an arrangement for non-reversible detection and display of electrical overcurrents or current limit values by means of a pre-finished conductor. The conductor according to the invention has at least two conductor sections, spaced apart from each other and extending parallel to each other, which are designed for current to flow through in the same direction. At least one of the parallel conductor sections has a protrusion, a nose, or similar blocking element, which limits the path of movement of a mechanical display or switching element, such that the electromagnetic force acting on the parallel conductor sections during the flow of current transitions the blocking element into a release position in respect of the path of movement of the mechanical display or switching element. Such an arrangement can be used particularly advantageously as a prior damage indicator in surge arresters.

The invention relates to an arrangement for non-reversible detection and display of electrical overcurrents or current limit values by means of a pre-finished conductor. The conductor according to the invention has at least two conductor sections, spaced apart from each other and extending parallel to each other, which are designed for current to flow through in the same direction. At least one of the parallel conductor sections has a protrusion, a nose, or similar blocking element, which limits the path of movement of a mechanical display or switching element, such that the electromagnetic force acting on the parallel conductor sections during the flow of current transitions the blocking element into a release position in respect of the path of movement of the mechanical display or switching element. Such an arrangement can be used particularly advantageously as a prior damage indicator in surge arresters.

An overvoltage protection device has a plurality of overvoltage arresters and a disconnecting apparatus. For each of the overvoltage arresters a blocking element is present, each of which is arranged so as to block the path of movement of a mechanically preloaded wedge slide having a wedge bevel. A rocker lever arrangement has first lever arms corresponding to the number of wedge slides and at least one second lever arm for blocking or releasing a displacement element, wherein ends of the first lever arms each have a surface for contacting the respective wedge bevel of the wedge slides in such a way that, when the respective path of movement is released, at least one of the wedge slides lifts the corresponding first lever arm with its wedge bevel, as a result of which the second lever arm releases the displacement element.

A varistor (50) comprising: a feed-through conductor (52) and a varistor disc (72) interposed between, and electrically connected to, conductor layers disposed on opposite surfaces of the varistor disc (72), the conductor layers being electrically isolated from one another; wherein the varistor disc (72) comprises a through aperture (60) through which the feed-through conductor extends; a first one of the conductor layers is electrically connected to the feed-through conductor; a second one of the conductor layers is, in normal use, permanently electrically connected to ground the varistor (50). This configuration enables one side of the disc (72) to be connected to the feed-through terminal, and the other side of the disc (72) to be connected to a ground plane, such as an earthed bulkhead of a wall or cabinet, via a metal plate forming part of the varistor (50) housing.

A varistor (50) comprising: a feed-through conductor (52) and a varistor disc (72) interposed between, and electrically connected to, conductor layers disposed on opposite surfaces of the varistor disc (72), the conductor layers being electrically isolated from one another; wherein the varistor disc (72) comprises a through aperture (60) through which the feed-through conductor extends; a first one of the conductor layers is electrically connected to the feed-through conductor; a second one of the conductor layers is, in normal use, permanently electrically connected to ground the varistor (50). This configuration enables one side of the disc (72) to be connected to the feed-through terminal, and the other side of the disc (72) to be connected to a ground plane, such as an earthed bulkhead of a wall or cabinet, via a metal plate forming part of the varistor (50) housing.

An electrical connector provided with a varistor, and to a protection device for incorporation into an electrical connector and having a varistor comprising at least two pins including a first pin which is a live (502) or neutral (504) pin and a second pin which is an earth pin (506), the first and second pins (502, 504, 506) extending through respective apertures (512) in a varistor plate (514) which has first and second faces, wherein a first conductive layer on the first face of the varistor plate (514) connects electrically to the first pin (502, 504) and a second conductive region on the second face of the varistor plate connects electrically to the second pin (506), so that in response to an excessive voltage across the first (502, 504) and second (506) pins the varistor plate will conduct electricity between the first (502, 504) and second (506) pins. The arrangement can easily be adopted in connectors conforming to existing standards, such as existing mains electrical plugs (500).

A three phase surge protection device is disclosed. In an embodiment a device include a stack comprising a first varistor, a second varistor and a third varistor, wherein the varistors are electrically connected to form a circuit and a first thermal disconnect configured to interrupt the circuit when a temperature of the first thermal disconnect exceeds a predefined temperature.

A thermally protected metal-oxide varistor is provided, including a disconnecting unit, a first varistor assembly and a second varistor assembly. The first varistor assembly and the second varistor assembly are connected in series through a low-melting-point alloy layer; wherein when the low-melting-point alloy layer is fused, the disconnecting unit acts to cut off the low-melting-point alloy. The two varistors are connected directly through solder joints without any transition connection member. The heat transfer path is reduced to the shortest path, and a faster response is realized compared to conventional products formed by a varistor and a disconnecting unit when abnormal over-current passes. Moreover, the slider functions as a physical separator capable of isolating the two varistors after the solder joints are fused, which further diminishes the risk of fire occurrence caused by the failure of instantly blocking current by the disconnecting unit when the varistor breaks down by over-current.

A surge protective device (SPD) module includes a module housing, first and second module electrical terminals mounted on the module housing, a gas discharge tube (GDT) mounted in the module housing, and a fail-safe mechanism mounted in the module housing. The GDT includes a first GDT terminal electrically connected to the first module electrical terminal and a second GDT terminal electrically connected to the second module electrical terminal. The fail-safe mechanism includes: an electrically conductive shorting bar positioned in a ready position and repositionable to a shorting position; a biasing member applying a biasing load to the shorting bar to direct the shorting bar from the ready position to the shorting position; and a meltable member. The meltable member maintains the shorting bar in the ready position and melts in response to a prescribed temperature to permit the shorting bar to transition from the ready position to the shorting position under the biasing load of the biasing member. In the shorting position, the shorting bar forms an electrical short circuit between the first and second GDT terminals to bypass the GDT.