EP2765590B1

EP2765590B1 - Tripping mechanism for surge protector and surge protector

Info

Publication number: EP2765590B1
Application number: EP12847145.5A
Authority: EP
Inventors: Wei Sun; Quanhe LIU
Original assignee: Schneider Electric Industries SAS
Current assignee: Schneider Electric Industries SAS
Priority date: 2011-11-07
Filing date: 2012-11-07
Publication date: 2016-10-19
Anticipated expiration: 2032-11-07
Also published as: CN103094013A; WO2013067923A1; BR112014010904A2; ZA201404030B; BR112014010904B1; EP2765590A4; EP2765590A1; CN103094013B; ES2611404T3

Description

TECHNICAL FIELD

This invention relates to a surge protector, and especially relates to a tripping mechanism for the surge protector.

BACKGROUND OF THE INVENTION

Surge protectors are commonly used in the electrical circuits used in families, offices and industrial sites, etc. to prevent damage to the electrical apparatus caused by the instantaneous overvoltage in the circuits. When peak current or voltage suddenly occurs in the electrical circuits or communication lines due to the external disturbance, the surge protector can conduct and divide the current in an extremely short time so as to avoid the damage to other apparatus in the circuits caused by the surge.
The most commonly used surge protector comprises an element called metal oxide varistor (MOV) for transferring the redundant voltage. The metal oxide varistor has a very large resistance in normal working state, and thus substantively shows an off state. When the voltage in the circuit exceeds the predetermined value, for example, under the circumstance of lightening strike, etc., the resistance of the MOV dramatically decreases, and thus the MOV is almost in a conductive state and transfers a large volume of current to eliminate redundant voltage.
However, after a long time use, the metal oxide varistor will age and thus generate heat. In order to prevent the metal oxide varistor from being damaged due to overheat, and to prevent disasters such as fire due to the rise of temperature, it is common to provide an tripping mechanism in the surge protector, the tripping mechanism and the metal oxide varistor are connected in series so that the metal oxide varistor disconnects with the circuit when the temperature rises.
Fig. 1 shows a tripping mechanism adopted by the prior art. The tripping mechanism mainly comprises a substantially plate-shaped tripping rod 1, the tripping rod 1 is mounted on a frame bracket 2 through a pivot 3 provided on the frame bracket 2 of the surge protector so as to be able to swing, and an upper end 11 of the tripping rod 1 is biased towards the right side of Fig. 1, i.e. towards the trip direction, by biasing springs 4. A remote signal switch lever 12 is integrally formed at a lower end of the tripping rod 1, the remote signal switch lever 12 cooperates with a remote signal switch (not shown) to trigger the remote signal switch. Furthermore, the middle portion of the tripping rod 1 is welded to MOV 5 through low-temperature solder (not shown), the tripping rod 1 is further connected to a terminal 9 of the surge protector through a lead 8, and the terminal 9 connects to an outside circuit. The other electrode of MOV 5 connects to the other terminal 10 of the surge protector, and thus the surge protector is connected to the circuit.
An indicator bracket 6, which indicates the current state of the surge protector, is provided at an upper side of the frame bracket 2, and the indicator bracket 6 is biased towards the right side of Fig. 1 by another biasing spring 7, i.e. the biasing direction is the same as the biasing direction that the biasing springs 4 bias the tripping rod 1. One end of the indicator bracket 6 is an indication part, commonly in green color, the indication part can be exposed through an opening provided on a housing (not shown) of the surge protector, and thus the indication part is visible from outside. Similarly, a red indication part is formed on the frame bracket 2 at a position corresponding to the green indication part.
In the normal working state, the tripping rod 1 is soldered to MOV 5 through low temperature solder, and the tripping rod 1 electrically and mechanically connects to MOV 5. Meanwhile, the tripping rod 1 is located at the position shown in Fig. 1, and the indicator bracket 6 is maintained at the position shown in Fig. 1 by abutting against the upper end of the tripping rod 1; and at the same time, the green indication part on the indicator bracket 6 covers the red indication part on the frame bracket 2, and thus the green indication part, which indicates that the surge protector is currently in normal working state, can be seen from outside of the housing of the surge protector.
When the temperature rises to a certain level, the low-temperature solder melts, the tripping rod 1 rotates clockwise about the pivot 3 in the figure under the action of the biasing springs 4, and thus the electrical connection between the tripping rod 1 and MOV 5 is disconnected. Meanwhile, the remote signal switch lever 12 at the lower end of the tripping rod 1 triggers the remote control switch with the rotation of the tripping rod 1 so as to send to the remote control apparatus a signal indicating the tripping of the tripping rod 1. Furthermore, since the tripping rod 1 rotates clockwise, the indicator bracket 6 slides towards right on the upper side of the frame bracket 2 under the action of the biasing spring 7, and thus the green indication part moves to the right side to expose the red indication part provided on the frame bracket 2, and thus the red indication part, which indicates the tripping of the surge protector, can be seen from outside of the housing of the surge protector.
However, the conventional tripping mechanism of the surge protector has following problems: the tripping rod 1 moves substantially in a plane parallel to a side of MOV 5, and thus even in the case that the tripping rod 1 trips, the electrical distance between the tripping rod 1 and the electrode of MOV 5 is very short, and this is disadvantageous to the electrical isolation between the tripping rod 1 and the electrode of MOV 5 in the trip state. Furthermore, the protection level and current leakage capacity of the standard MOV product are limited, and the cost of adopting non-standard single sheet product is high. So, for example, when a nominal discharge current of 35kA is required, two standard single sheet MOVs of 20kA are usually used to achieve this, so a solution occurs where two MOVs are used. In the case of adopting two or more MOVs, two or more tripping mechanisms mentioned above are needed, i.e. another tripping rod 1 is provided in a similar manner on the rear side not shown in the figure, and the another tripping rod 1 is soldered to another MOV located on the rear side of the figure. However, when the temperature rises, the two tripping rods 1 operate independently, it is difficult for the conventional tripping mechanism mentioned above to meet the needs that the two MOVs trip simultaneously. If it cannot be ensured that the two MOVs trip simultaneously, such a case may occur that one MOV trips while the other fails to trip, the standard signal sheet MOV of 20kA may cause MOV explosion in a 35kA surge circumstance.
Further, US 2008/0043395 A1 discloses a tripping mechanism for a surge protector with a frame bracket for receiving at least one metal oxide varistor and disconnector means arranged on the frame bracket and connected to an electrode of the metal oxide rheostat via solder. The tripping mechanism comprises a slider slidably arranged on the bracket frame, the slider being slidable between a first position and a second position and being biased towards a trip position. In a normal working state, the slider is being maintained at the first position by the disconnector means counteracting the biasing pressure, and in a trip state, the sliding movement of the slider towards the second position under the action of the biasing pressure causing the disconnector means to bend in a direction away from the electrode of the metal oxide varistor.

SUMMARY OF THE INVENTION

This invention is made based on the problems of the prior art, and an object of the invention is to provide a tripping mechanism for a surge protector, the tripping mechanism can ensure the electrical distance between a tripping rod and MOV in the trip state, and when a plurality of MOVs are used, simultaneously tripping of the plurality of MOVs can be easily realized.
According to one aspect of the invention, there is provided a tripping mechanism, the tripping mechanism comprising: a frame bracket for receiving at least one metal oxide varistor; and a tripping rod pivotably arranged on the frame bracket and connected to the one electrode of the electrodes of the metal oxide rheostat via low temperature solder. The tripping mechanism further comprises a slidable block slidably arranged on the bracket frame, the slidable block is slidable between a first position and a second position and is biased towards a trip position; in a normal working state, the slidable block is maintained at the first position by the tripping rod counteracting the biasing pressure, and in a trip state, the sliding movement of the slidable block towards the second position under the action of the biasing pressure causes the tripping rod to pivot in a direction away from the electrode of the metal oxide varistor.
Thus, in the trip state, since the tripping rod pivots away from the electrode of the metal oxide varistor, the electrical distance between the tripping rod and the electrode of the metal oxide varistor is increased, and thus the reliability of the electric insulation between the tripping rod and the electrode of the metal oxide varistor is improved.
According to a second aspect of the invention, the slidable block is located between the electrode and the tripping rod when the slidable block is at the second position. This further improves the reliability of the electric insulation.
The tripping mechanism further is further provided with a swing arm which is pivotally mounted on the frame bracket, and the sliding movement of the slidable block towards the second position causes the swing arm to pivot to trigger a remote control switch.
Thus, the tripping of the tripping rod and the swing of the swing arm are both realized by the movement of the slidable block, so the structure of the whole tripping mechanism is simplified, the manufacture cost is reduced and the reliability of the mechanism is improved.
Preferably, the slidable block is provided a state indication part indicating the normal working state, and when the slidable block is at the first position, the state indication part is visible from outside through an opening or a transparent window provided in a housing of the surge protector.
Furthermore, the frame bracket is provided with a state indication part indicating the trip state, when the slidable block is at the first position, the state indication part indicating the trip state is shielded by the state indication part indicating the normal working state provided on the slidable block, and when the slidable block is at the second position, the state indication part indicating the trip state is exposed and is visible from outside through the opening or the transparent window provided on the housing of the surge protector.
Preferably, the slidable block comprises an inclined surface, the tripping rod abuts against the inclined surface when the slidable block is at the first position.
Thus, a simple structure can be used to make the tripping rod trip.
Preferably, a channel is provided on a lower side of the inclined surface, the electrode is received in the channel when the slidable block is at the second position.
Thus, in the trip state, besides increasing the distance between the tripping rod and the electrode, the slidable block is located between the tripping rod and the electrode of MOV, and receives the electrode in its channel, further enhancing the electrical insulation strength between the tripping rod and the electrode of MOV.
Alternatively, the tripping mechanism further comprises one or more biasing springs, one end of which is attached to the slidable block, and the other end of which is attached to the frame bracket to bias the slidable block towards the second position.
Preferably, a first end of the tripping rod pivotably connects to the frame bracket, and a second end of the tripping rod is welded to the electrode. Specifically, the second end of the tripping rod is formed with a slit, and the electrode is inserted into the slit and is welded thereto.
The welding reliability between the electrode of MOV and the tripping rod can be improved by inserting the electrode of MOV into slit and being welded at the slit, and such lateral soldering method can reduce the thermal impact of the surge on the MOV.
According to the other aspect of the invention, two metal oxide varistors are received in the bracket frame of the tripping mechanism, and the respective electrodes of the two metal oxide varistors are welded at the same position of the same tripping rod, i.e. the two respective electrodes of the two metal oxide varistors are both inserted into the slit of the tripping rod and are welded there through low-temperature solder.
According to another aspect of the invention, there is provided a surge protector which comprises the above tripping mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, characteristics, advantages and technical and industrial importance of this invention will be more clearly understood from the following detailed description of the preferable embodiment of this invention taken in conjunction with the accompanying drawings in which:

Fig. 1 is a schematic view of a tripping mechanism of a surge protector in the prior art;
Fig. 2A is an exploded perspective view showing the tripping mechanism of the surge protector according to a preferred embodiment of the invention, the tripping mechanism comprises one MOV;
Fig. 2B is a perspective view of the tripping mechanism after being assembled shown in Fig. 2A;
Fig. 3A is a side view of the tripping mechanism shown in Fig. 2B;
Fig. 3B is a cross-sectional view taken along line B-B in Fig.3A;
Fig. 3C is an amplified view of the circled section in Fig. 3B;
Fig. 4 is a perspective view of the tripping mechanism in the normal working state;
Fig. 5 is a perspective view of the tripping mechanism in the trip state;
Fig. 6A is an exploded perspective view illustrating the tripping mechanism of the surge protector according to another preferable embodiment of the invention, the tripping mechanism comprises two MOVs;
Fig. 6B is a perspective view of the tripping mechanism after being assembled shown in Fig. 6A;
Fig, 7A is a side view of the tripping mechanism shown in Fig. 6B;
Fig. 7B is a cross-sectional view taken along line B-B in Fig, 7A; and
Fig. 7C is an amplified view of the circled section in Fig. 7B.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, the tripping mechanism according to the preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.
Refereing to Figs. 2A to 5, a tripping mechanism 100 according to the first embodiment of the invention is disclosed. The tripping mechanism 100 comprises a frame bracket 110, the frame bracket 110 is substantially in the form of a square frame and is used to receive a MOV 200. A pivot 111 is formed at the right upper corner of the frame bracket 110, and a tripping rod 120 is pivotably arranged on the frame bracket 110 around the pivot 111. Specifically, a circular recess or a hole can be formed at one end 121 (the right end in the drawing) of the tripping rod 120, and the pivot 111 is inserted into the circular recess or the hole. Furthermore, the tripping rod 120 is connected to a terminal 300 of the surge protector through a lead 122, and the terminal 300 is used for connecting the surge protector with an external circuit.
As clearly shown in Figs. 4 and 5, the other end of the tripping rod 120 is a connection end, the connection end is substantially in the form of a flat panel, a concave platform 123 is formed at substantially the meddle part of the flat panel in the width direction of the flat panel shaped connection end, and the concave platform 123 is formed with a through slit 124 at its middle portion, the through slit 124 may open at one end or both ends of the through slit 124 are closed.
A slidable block 130 is arranged on an upper side surface of the frame bracket 110. The slidable block 130 is slidably arranged on the upper side surface of the frame bracket 110, for example, a guide portion 112 is provided on the frame bracket 110, and the slidable block 130 can slide under the guidance of the guide portion 112. Meanwhile, as shown in the drawings, biasing springs 140 are further provided (two springs in the drawing), one end of the biasing springs is attached to the right end of the slidable block 130, and the other end of the biasing springs is attached to the pivot 111, and thus the slidable block 130 is biased towards the right side under the action of the biasing springs 140, i.e. is biased towards the pivot 111. At the bottom of the slidable block 130 there is formed with a channel 134 along the longitudinal direction, the channel 134 is used to prevent the slidable block 130 from interfering with the electrode 210 of MOV 200 during the sliding of the slidable block 130, and this will be described later. The slidable block 130 is formed with an indication part 131, i.e. a green indication part, at its left end. Similar to the prior art, in the state as shown in Fig. 2B, the green indication part is exposed through an opening or a window provided in the housing of the surge protector to indicate that the surge protector is in a normal working state.
Another pivot 113 is formed at the lower side of the frame bracket 110, a swing arm 150 is pivtoably arranged on the frame bracket 110 through the pivot 113, and one end (the lower end in the drawing) of the swing arm 150 is formed with a switch trigger part 151 for triggering a remote control switch which is not shown in the drawing. The other end (the upper end in the drawing) of the swing arm 150, as shown in Fig. 4, is formed with a driven portion 152 which engages with a protrusion 132 provided on the slidable block 130, and the protrusion will push the swing arm 150 to rotate clockwise about the pivot 113 when the slidable block 130 slides towards the right side.
As shown in Fig. 2A, the MOV 200 comprises two electrodes 210 and 220. As shown in Figs. 3C and 4, in the normal working state, the MOV 200 is received in the frame bracket 110, and one electrode 210 of the MOV is inserted into the slit 124 formed in the concave platform 123 of the tripping rod 120, and is connected to the tripping rod 120 through a low temperature solder 400. The other electrode 220 of the MOV 200 is connected to the other terminal 500 of the surge protector, e.g. through welding, while the other terminal 500 is connected to an external circuit. On one hand, the MOV 200 is connected to one phase of the external circuit through the tripping rod 120 and the terminal 300, and on the other hand, is connected to the other phase of the external circuit through the other electrode 220 and the other terminal 500 of the surge protector, and when the voltage between the two phases of the external circuit exceeds the predetermined voltage, the MOV 200 conducts the two phases and functions to divide the current and reduce the voltage.
As shown in Fig. 4, in the normal working state, the middle part of the slidable block 130 is formed with an inclined surface 133, an edge of the connection end of the tripping rod 120 abuts against the inclined surface 133, and thus preventing the slidable block 130 from moving towards the pivot 111 by the biasing spring 140. In such a state, the slidable block 130 is located at the first position, the indication part 131 is visible from outside through the opening or the transparent window provided on the housing of the surge protector, thus indicating that the surge protector is in a normal working state.
When the temperature in the surge protector rises and reaches or exceeds the predetermined temperature threshold value, the low temperature solder 400 melts, and at this time, the connection between the tripping rod 120 and the electrode 210 of the MOV 200 is released, and thus the tripping rod 120 cannot serve the function of preventing the slidable block 130 from sliding anymore. Under such circumstance, the sildable block 130 slides towards the right side direction in the drawing under the action of the biasing pressure of the biasing springs 140, and at the same time, the inclined surface 133 of the sliable block 130 pushes the tripping rod 120 upward to make the tripping rod 120 rotate clockwise in the drawing about the pivot 111. Fig. 5 shows the tripping mechanism in the trip state. In the state shown in Fig. 5, the slidable block 130 has slided to the second position on the right side, pushing the tripping rod 120 away upward, and at the same time the slidable block 130 covers the electrode 210 of the MOV 200; at this time, the electrode 210 is received in the channel 134, and thus the electrode 210 and the tripping rod 130 are electrically isolated. Meanwhile, as can be seen from Fig. 5, the green indication part 131 has moved to the light, and thus a red indication part 114, which is provided on the frame bracket 110 and was shielded by the green indication part 131, is exposed. As the slidable block slides towards right, the protrusion 132 on the slidable block 130 pushes the driven portion 152 of the swing arm 150, making the swing arm 150 rotate clockwise about the pivot 113, and thus the switch trigger part 151 triggers the remote control switch (not shown), sending surge protector tripping signal to the remote control apparatus.
Figs. 6 and 7 show the tripping mechanism according to the second embodiment of the invention, the structure of this tripping mechanism is substantially the same as that of the one described above, the difference lies in that the frame bracket 110 receives two MOVs 200. Thus, as shown in Fig. 7C, the electrodes of the MOVs 200 are both inserted into the slit 240 of the tripping rod 120, and are welded to the tripping rod 120 through low-temperature solder 400. Thus, when the temperature rises, even in the case that two MOVs 200 transfer different amount of heat to the welding point through their respective electrode, since the heat is applied to the same welding point, and thus the mechanism trips simultaneously. Since other parts of the second embodiment are the same as the first embodiment, and the description is omitted.
According to the tripping mechanism of the invention, in the trip state, the tripping rod 120 rotates in a direction away from the electrode 210 of the MOV 200, as a result, the electrical distance between the tripping rod 120 and the electrode 210 is increased, the reliability of the electrical insulation between the tripping rod 120 and the electrode 210 is improved.
Furthermore, according to the tripping mechanism of the invention, in the trip state, the slidable block 130 slides to a position between the tripping rod 120 and the electrode 210 of the MOV 200, and covers the electrode 210 of the MOV 200, and thus the electrical insulation strength between the tripping rod 120 and the electrode 210 is further enhanced.
Furthermore, according to the tripping mechanism of the invention, the electrodes 210 of two MOVs 200 are welded at the same position of the tripping rod 120 by using low-temperature solder, when the temperature rises, even if two MOVs 200 transfer different amount of heat to the welding point through their respective electrode, since the hest is applied to the same welding point, the mechanism will trip simultaneously, and thus improve the reliability of the tripping mechanism.
Furthermore, according to this invention, both the pivoting of the tripping rod 120 and the swing of the swing arm 150 are activated by the sliding of the slidable block 130, as a result, the structure of the whole tripping mechanism is simplified, the cost of the production is saved and the reliability of the whole tripping mechanism is improved.

Claims

A tripping mechanism (100) for a surge protector, the tripping mechanism (100) comprising:
a frame bracket (110) for receiving at least one metal oxide varistor (200); and

a tripping rod (120) pivotably arranged on the frame bracket (110) and connected to an electrode (210) of the metal oxide varistor via low temperature solder,

wherein

the tripping mechanism (100) further comprising a slidable block (130) slidably arranged on the bracket frame (110), the slidable block (130) being slidable between a first position and a second position and being biased towards a trip position; in a normal working state, the slidable block (130) being maintained at the first position by the tripping rod (120) counteracting the biasing pressure, and in a trip state, the sliding movement of the slidable block (130) towards the second position under the action of the biasing pressure causing the tripping rod (120) to pivot in a direction away from the electrode (210) of the metal oxide varistor (200),

characterised in that

the slidable block (130) is located between the electrode (210) and the tripping rod (120) when the slidable block (130) is at the second position.
The tripping mechanism according to claim 1, characterized in that further comprising a swing arm (150) pivotally mounted on the frame bracket (110), and the sliding movement of the slidable block (130) towards the second position causes the swing arm (150) to pivot so as to trigger a remote control switch.
The tripping mechanism according to claim 1, characterized in that the slidable block (130) is provided with a state indication part (131) indicating the normal working state, and when the slidable block is at the first position, the state indication part (131) is visible from outside through an opening or a transparent window arranged in a housing of the surge protector.
The tripping mechanism according to claim 3, characterized in that the frame bracket (110) is provided with a state indication part (114) indicating the trip state, when the slidable block (130) is at the first position, the state indication part (114) indicating the trip state is shielded by the state indication part (131) indicating the normal working state provided on the slidable block (130), and when the slidable block (130) is at the second position, the state indication part (114) indicating the trip state is exposed and is visible from outside through the opening or the transparent window provided on the housing of the surge protector.
The tripping mechanism according to claim 1, characterized in that the slidable block (130) comprises an inclined surface (133), the tripping rod (120) abuts against the inclined surface (133) when the slidable block (130) is at the first position.
The tripping mechanism according to claim 1, characterized in that a channel (134) is provided on a lower side of the inclined surface (133), the electrode (210) is received in the channel (134) when the slidable block (130) is at the second position.
The tripping mechanism according to claim 1, characterized in that further comprising one or more biasing springs (140), one end of the spring(s) is(are) attached to the slidable block (130), and the other end of the spring(s) is(are) attached to the frame bracket (110) to bias the slidable block (130) towards the second position.
The tripping mechanism according to claim 1, characterized in that a first end of the tripping rod (120) pivotably connects to the frame bracket (110), and a second end of the tripping rod is welded to the electrode (210).
The tripping mechanism according to claim 8, characterized in that the second end of the tripping rod (210) is formed with a slit (124), and the electrode (210) is inserted into the slit (124) and is welded thereto.
The tripping mechanism according to any one of the above claims, characterized in that the two metal oxide varistors (200) are received in the bracket frame (110), and the respective electrodes (210) of the two metal oxide varistors (200) are welded at the same position of the same tripping rod (120).
A surge protector, characterized in that the surge protector comprising at least one metal oxide varistor (200) and a tripping mechanism (100) according to any one of Claims 1 to 10.