EP2194542A2

EP2194542A2 - Device for overvoltage protection with protection status signalling

Info

Publication number: EP2194542A2
Application number: EP09177872A
Authority: EP
Inventors: Jozef Cernicka
Original assignee: Kiwa sro
Current assignee: Kiwa sro
Priority date: 2008-12-03
Filing date: 2009-12-03
Publication date: 2010-06-09
Also published as: CZ2008764A3; EP2194542A3

Abstract

The invention relates to the device for overvoltage protection with protection status signalling, which comprises the spring-loaded shifting member (5), which is in direction of its length positioned displaceably and is provided with profiled guiding groove (52), into which engages the first pin (60) of signalling lever (6), which is provided with an end (64) for visual signalling in a window (1 e1) in the body (1), at the same time the shifting member (5) acts by a pressing force upon the second electrically conductive member (44) and its first low-melting joint (43) with second electrode (42) of non-linear resistance element (4), while the second electrically conductive member (44) is further connected with connecting terminal (10) of the device. The shifting member (5) is by its length situated in direction (H) of height of the body (1) and on its end at the wall (11) of the body (1) it is provided with retaining recess (53) opened from above,, the retaining recess (53) has a shorter length than the length of profiled guiding groove (52), and into the retaining recess (53) is extending the second pin (61) of signalling lever (6).

Description

Technical field

The invention relates to the device for overvoltage protection with protection status signalling, which comprises the spring-loaded shifting member, which in direction of its length is positioned displaceably and is provided with profiled guiding groove, into which engages the first pin of signalling lever, which is provided with an end for visual signalling in a window in the body, at the same time the shifting member acts by a pressing force upon the second electrically conductive member and its first low-melting joint with second electrode of non-linear resistance element, while the second electrically conductive member is further connected with connecting terminal of the device.

Background art

Overvoltage protection contains a protective element which is generally represented by a non-linear resistance element (varistor), which due to its loading of electric current and by an impulse loading of a protected network gradually decreases the value of its resistance. Due to this, the current running through the protective element is increasing and warming up of the protective element increases as well. Therefore the overvoltage protection is provided with temperature cut-off device which serves for cutting off the protective element as this protective element due to its warming is not able to fulfil properly its function any more. Cutting-off of the protective element from the network is signalled, this either visually directly on the overvoltage protection or remotely by a transmission of a suitable signal. Once the protective element is cut off from the network, the network is after then not protected, so it is necessary to renew the protected status by replacement of the protective element of overvoltage protection.
Especially at the overvoltage protection of category II is, according to the IEC 61643-11, the visual signalling of overvoltage protection status is required. This signalling distinguishes two modes of status, one being the "good one" - green colour, and the "fault one" - red colour. The status modes may be expressed even differently than through this colour convention. The disadvantage of such signalling is that it does not express in any way the status when the overvoltage protection is already partially depreciated nevertheless it is not yet disconnected from the protected circuit by means of an inbuilt cut-off device. Due to the fact that only the connected status to the protected circuit or disconnected status from the protected circuit is being signalled, such a situation occurs that in the period during cutting-off the overvoltage protection due to its deterioration and the moment when the non-functioning (cut-off) overvoltage protection is replaced by a functioning one, the respective electrical circuit is not protected, thus the risk of damage of the non-protected electrical equipment owing to the overvoltage is increased.
Known are other solutions ensuring a three-stage signalling of overvoltage protection, e.g. by means of a pair of parallel connected varistors which are equipped with a couple of cut-off mechanisms, each having its own spring. Function of both cut-off mechanisms always depends on temperature of both varistors, while one of the cut-off mechanisms disconnects at lower temperature of varistors than the second one. The window of visual signalling shows a green light in case the overvoltage protection is in flawless status. Owing to the operation load and ageing of varistors these varistors are warmed up till the cut-off device with lower temperature of disconnection is disconnected and through acting of the first cut-off device the window of visual signalling is screened with a yellow colour, which creates a visual information on partial deterioration of overvoltage protection which is, henceforth functioning. Simultaneously through movement of the first cut-off mechanism, the remote status signalling of overvoltage protection is activated. As a result of further increasing of varistor temperature, upon co-acting of the second spring, the second cut-off mechanism is disconnected, whose movement screens the window of visual signalling with a red colour which means that the overvoltage protection is totally deteriorated and is disconnected from the protected circuit.
Disadvantage of this solution is in considerable complexity and doubling of several functional elements which results in higher production costs.
These disadvantages are to a certain degree remedied by a device known from WO 2007/017736 A1 , which comprises a basic part (holder) for fastening to the installation slat and a slide-in protective element which is inserted in the basic part, with which in the inserted status is electrically connected by means of its contacts. The slide-in protective element comprises a non-linear resistance element and its cut-off device. In this solution the three-stage signalling of status of overvoltage protection is achieved by a single cut-off device, which is equipped with means for at least two-stage motion of actuator depending on temperature of non-linear resistance element, while the actuator is coupled with signalling device of a gradual motion of the actuator. The actuator is formed of shifting part, which is displaceably and with pushing action against the low-melting joint of electrically conducting wire with one electrode of non-linear resistance element mounted in the body of the slide-in protective element. Shifting element is further provided with at least one surface for acting upon the signalling lever and further is provided with at least one surface for acting upon the positioning member of remote signalling mounted in the holder. The shifting part is further with its one end assigned to a wire, on which through a low-melting joint with lower temperature necessary for releasing than the low-melting joint of the wire and electrode of non-linear resistance element, is attached the stop, against which the shifting part is leaning in distance from the place of its acting upon the wire after releasing the low-melting joint of the stop and wire. So, this is a specific combination of shifting element, the rotating signalling lever and the low-melting joints with a different temperature of melting.
Disadvantage of the background art is that at necessity of overvoltage protection of higher or high performance, also due to limited external dimensions of the standardised basic part (holder) as well as of the slide-in protective element it is practically impossible to use arrangement with replaceable slide-in protective elements, because the needed non-linear resistance elements are of greater dimensions.
Therefore for higher and high protective performances the single-piece overvoltage protections are used, at which external shape and the size like at the multi-piece overvoltage protections containing the basic part and slide-in protective element are preserved. Inner area of such single-piece overvoltage protection has an arrangement adjusted to needed size of non-linear resistance elements. With respect to a different arrangement of inner area of these single-piece overvoltage protections, an easy transfer of the known arrangements of visual three-stage signalling it is not an ideal solution, because the known arrangements are optimised just for a detachable slide-in protective element.
Hence, the goal of this invention is to draft a new functional arrangement of a three-stage signalling of status of overvoltage protection.

Principle of the invention

The goal of the invention is achieved by the device for overvoltage protection with protection status signalling, whose principle consists in that the shifting member is by its length situated in direction of height of the body and is on its end at the wall of the body provided with retaining recess opened from above, the retaining recess has a shorter length than is the length of profiled guiding groove, and into the retaining recess is extending the second pin of signalling lever.
The advantage of this solution consists in that it is reliable, relatively simple and not demanding as to production. By arrangement of all functional means for disconnecting of non-linear resistance element from the protected circuit and the means for protection status signalling at lower and lateral side of middle part of the body of the device for overvoltage protection is totally emptied the middle section of the body of the device for overvoltage protection, which is significantly better usable for placing of required, smaller or greater, quantity of non-linear resistance elements.
The preferred embodiments of the invention are described in dependent patent claims and in description of exemplary embodiments, while their subject matter is the three-stage signalling of protection status and remote signalling of protection status.

Description of the drawing

The invention is schematically represented in the drawing, where the Fig. 1 shows a longitudinal section of arrangement of one-piece overvoltage protection of category II in position "entirely functioning", the Fig. 1a cross section through G-G plane of arrangement of one-piece overvoltage protection of category II in position "entirely functioning", the Fig. 1b window of visual signalling of status of one-piece overvoltage protection of category II in position "entirely functioning", the Fig. 2 a longitudinal cross-section through arrangement of one-piece overvoltage protection of category II in position "approaching fallout", the Fig. 2a cross section through G-G plane of arrangement of one-piece overvoltage protection of category II in position "approaching fallout", the Fig. 2b window of visual signalling of status of one-piece overvoltage protection of category II in position "approaching fallout", the Fig. 3 longitudinal section through arrangement of one-piece overvoltage protection of category II in position "not-functioning - fallout", the Fig. 3a cross section through G-G plane of arrangement of one-piece overvoltage protection of category II in position "not functioning - fallout" and the Fig. 3b window of visual signalling of status of one-piece overvoltage protection of category II in position "not functioning - fallout".

Examples of embodiment

The device for overvoltage protection comprises the body 1, which is provided with system of cavities for mounting of individual functional elements of overvoltage protection. The device for overvoltage protection is created as a one-phase, i.e. for one phase of three phase electric line or it is created as more-phase, when in one body 1 side by side are arranged the working elements for several phases of three-phase electric line, e.g. for each phase of three-phase electric line, etc. Also more one-phase devices for overvoltage protections may with their bodies 1 be connected into a larger unit, e.g. by means of rivets, etc.
The body 1 comprises a couple of arms 1a and 1b, in which there are arranged connecting terminals 10 for connection of electric wires of protected electric circuit. Between arms 1a and 1b is arranged the middle part 1e with the space for functional elements of overvoltage protection.
In the middle part 1e of the body 1 is mounted a non-linear resistance element 4, which is in the represented example of embodiment formed as a flat varistor. Non-linear resistance element 4 is with its first electrode 40 electrically conductively by means of the first electrically conductive member 41 connected with one connecting terminal 10 for connection of electric wires of protected electric circuit. With its second electrode 42 , which is laying in direction to the second connecting terminal 10 for connection of electric wires of protected electric circuit, is the non-linear resistance element 4 by means of the first low-melting electrically conductive joint 43 connected with first end 440 of the second electrically conductive member 44 , whose second end 441 is connected with second connecting terminal 10 for connection of electric wires of protected electric circuit. The first end 440 of second electrically conductive element 44 at least partially overlaps the second electrode 42 of non-linear resistance element 4, let us say the first end 440 of second electrically conductive element 44 is by one its side laying on the second electrode 42 of non-linear resistance element 4 . Between its first end 440 and second end 441 the second electrically conductive element 44 is arranged into an arch or into a similar shape, and in the place behind the second electrode 42 of non-linear resistance element 4 it creates the bend 442.
On the first end 440 of the second electrically conductive element 44 on the side reverse to the second electrode 42 of non-linear resistance element 4 is mounted the angle cover plate 45 , which is by means of the second low-melting electrically conductive joint 46 fastened to the first end 440 of second electrically conductive element 44. The angle cover plate 45 comprises the bent section 450, which has distance from the bend 442 on the first end 440 of the second electrically conductive element 44.
The first low-melting electrically conductive joint 43 has a higher melting temperature than is the melting temperature of the second low-melting electrically conductive joint 46.
The second electrically conductive element 44 is situated with its length in direction H of height of the body 1, while between the bent section 450 of angle cover plate 45 and the bend 442 of the second electrically conductive element 44 there is the gap 47.
The spring-loaded shifting member 5 is with its stop end 50 leaning against the bent section 450 of the angle cover plate 45. The shifting member 5 is in represented example of embodiment spring-loaded by means of compression spring 51 , which is with its one end leaning against shifting member 5, let us say against the bottom of recess in the shifting member 5 , while with its second end it is leaning against opposite wall 11 of the body 1. The shifting member 5 is situated displaceably in direction H of height of the body 1.
The shifting member 5 is in longitudinal direction provided with profiled guiding groove 52 , which in its first part 520 in direction H comprises lateral protrusion. On its end at the wall 11 of the body 1 the shifting member 5 is provided with retaining recess 53 opened from above. Length of the retaining recess 53 in direction H corresponds to distance of the bent section 450 of angle cover plate 45 from the bend 442 on the first end 440 of second electrically conductive element 44 , the length of displacement of shifting member 5 from starting position into the first position. At the same time the length of retaining recess 53 corresponds to the length of the first part 520 of the guiding groove 52.
Into the guiding groove 52 of shifting member 5 extends the first pin 60 of signalling lever 6, and into the retaining recess 53 extends the second pin 61 of signalling lever 6. The first pin 60 as well as the second pin 61 of signalling lever 6 are situated in central part of length of the signalling lever 6 . The signalling lever 6, which is situated in direction H of height of the body 1 on frontier of the arm 1a and middle part 1e of the body 1 , on its end 62 for remote signalling is provided with third pin 63, which extends into guiding gap 70 created on one end of the shifting plate 7. On its end 64 for visual signalling, which extends to circumferential wall 1e0 of middle part 1e of the body 1, the signalling lever 6 is provided with signalling surface 640 of status "approaching fallout" and "not functioning - fallout". In circumferential wall 1e0 of middle part 1e of the body 1 there is window 1e1 of visual status signalling. In visual field of the window 1e1 is inside the body 1 situated the signalling surface 1e2 of the status "entirely functioning".
As mentioned above, the third pin 63 of signalling lever 6 extends into the guiding gap 70 on one end of the shifting plate 7, which is in linear manner displaceably in direction W of width of the body 1 mounted in linear guiding means, which are in the represented example of embodiment formed of walls 12 and 13 created at the lower edge of the body 1. Direction W is in principle perpendicular to direction H .
On its second end is the shifting plate 7 provided with askew surface 71, by which in functioning state of the overvoltage protection is sitting on the askew face 80 of the hollow spring-loaded shifting pin 8 of remote signalling of status. The hollow spring-loaded shifting pin 8 of remote signalling of status is displaceable in direction H of height of the body 1, while it is spring-loaded by means of a compression spring 82 mounted in its cavity and leaning with one end on bottom of the cavity of shifting pin 8 and with the second end leaning against the lower wall of the body 1. On its lower end is the hollow spring-loaded shifting pin 8 provided with flange 81 , on whose upper side is in principle freely sitting one end of the lever 9 of remote signalling of status, the lever 9 is with its second end, in swivelling manner, mounted in the body 1 . From upper side is to the lever 9 of remote signalling of status assigned the detector 90 of extension of the hollow spring-loaded shifting pin 8 , while the detector 90 is coupled with remote place, on which the status of overvoltage protection is being displayed. In the represented example of embodiment the detector 90 is formed of microswitch.
In represented example of embodiment all elements inside the body 1 are situated in each status of overvoltage protection entirely outside the space limited by contour of the non-linear resistance element 4 when viewing in direction perpendicular to side surface of the non-linear resistance element 4 . In this arrangement, it is possible into a single type and size of the body 1, without necessity to modify inner arrangement, to position the necessary number of parallel connected non-linear resistance elements 4. Upon usage of lower than maximum number of non-linear resistance elements 4 the remaining space of the body 1 between the side wall of non-linear resistance elements 4 and the side wall of the body 1 is free and no one element of device for overvoltage protection extends to it.
The device for overvoltage protection according to this invention works in the following way.
Once overvoltage occurs in the protected electric circuit, the device for overvoltage protection fulfils normally its function, i.e. decreases overvoltage in protected circuit to the permissible value. Owing to ageing and overloading of non-linear resistance element 4 nevertheless the properties of protective element are changing, as a result of which electric current starts to gradually run through the non-linear resistance element 4 , which causes warming-up of the non-linear resistance element 4. Naturally, the thermal energy from the non-linear resistance element 4 is brought to electrodes 40 and 42 of the non-linear resistance element 4, which gradually becoming warm. In this state in the visual field of the window 1e1 is arranged the signalling surface 1e2 of the status "entirely functioning".
Through sufficient warming-up of the second electrode 42 there is melted the second low-melting electrically conductive joint 46 by which is the first end 440 of the second electrically conductive element 44 connected with angle cover plate 45 . Through this, the joint 46 of the second electrically conductive element 44 and the angle cover plate 45 looses its rigidity and the shifting member 5 starts by acting of compression spring 51 and its stop end 50 to shift the angle cover plate 45 in direction down to the bend 442 on electrically conductive element 44 , against which it stops. Electrically conductive element 44 is permanently electrically in a conductive manner connected with the second electrode 42 of non-linear resistance element 4 , and the non-linear resistance element 4 is still connected to protected electric circuit. By this restricted movement of the shifting element 5 the profiled groove 52 starts to move, walls of the groove 52 act on the first pin 60 of signalling lever 6 and they deflect it to the side in direction W , as it is represented in the Fig. 2, while the second pin 61 of signalling lever 6 remains caught in the retaining recess 53, by which is caused simultaneous shifting of the end 62 of signalling lever 6 in direction W for remote signalling and shifting of the end 64 against the direction W for visual signalling.
By this shifting of the end 62 for remote signalling the third pin 63 is acting upon the shifting plate 7 and the shifting plate moves in direction W . The shifting plate 7 unlocks the way for the shifting pin 8 , which extends upwards and the flange 81 presses the lever 9 of remote signalling to detector 90 of extension of the hollow spring-loaded shifting pin 8 and the detector 9 emits a remote signal about change in status of overvoltage protection.
By shifting the end 64 for visual signalling, the front section of the end 64 is set into visual field of the window 1e1, by which in visual field of the window 1e1 the visual signalling of status "approaching fallout" appears, as represented in the Fig. 2b.
Through further warming of the second electrode 42 of non-linear resistance element 4 there is melted the first low-melting electrically conductive joint 43, by which the second electrode 42 is connected with the first end 440 of the second electrically conductive element 44 . By this the joint 43 of the second electrically conductive element 44 and second electrode 42 looses its rigidity and, as represented in the Fig. 3, the shifting member 5 by acting of the compression spring 51 and its stop end 50 further shifts the angle cover plate 45 and now also the first end 440 of the second electrically conductive element 44 in direction downwards till the first end 440 of the second electrically conductive element 44 is transfered outside electric conductive contact with the second electrode 42, as it is represented in the Fig. 3a. By this further motion of the shifting element 5 another motion of the profiled guiding groove 52 occurs, the walls of the groove 52 again act upon the first pin 60 of signalling lever 6 and they deflect it to an opposite side against the direction W , as represented in the Fig. 3, while the second pin 61 of signalling lever 6 is released by running out from the retaining recess 53 . Through this is enabled slewing of the signalling lever 6 on the first pin 60. This slewing of signalling lever 6 on the first pin 60 causes another shifting of the end 64 for visual signalling against direction W , and rear part of the end 64 for visual signalling is set into visual field of the window 1e1 , by which in the visual field of the window 1e1 the visual signalling of status "not functioning - fallout" appears, as represented in the Fig. 3b. The end 62 of signalling lever 6 does not perform any motion, while the defect was already signalled remotely in the previous step according to the Fig. 2, 2a and 2b.
In the not represented example of embodiment is the device for overvoltage protection created as a device with two-stage signalling, i.e. with status signalling "entirely functioning" and status "not functioning - fallout". This device with two-stage signalling of status does not comprise the angle cover plate 45, next to this it does not comprise the second low-melting electrically conductive joint 46 and it also does not comprise on the front part of the end 64 for visual signalling the colourful surface for visual signalling of the status "approaching fallout". Upon sufficient warming of the second electrode 42 of non-linear resistance element 4 the first low-melting electrically conductive joint 43 is melted, by which the shifting element 5 shifts downwards by its whole track in one single step, it transfers the first end 440 of the second electrically conductive element 44 outside the electric conductive contact with second electrode 42, the first pin 60 of signalling lever 6 arrives to the end of the groove 52, and the second pin 61 of signalling lever 6 releases by running out from the retaining recess 53. This enables slewing of signalling lever 6 on the first pin 60 and shifting of the end 64 for visual signalling against direction W, by which into the visual field of the window 1e1 the end 64 for visual signalling with signalling of status "not functioning - fallout" is set. Simultaneously with this slewing of signalling lever 6 the end 62 for remote signalling shifts in direction W , the third pin 63 acts on the shifting plate 7 and the shifting plate 7 shifts in direction W. The shifting plate 7 so releases the way for the shifting pin 8, which extends upwards and the flange 81 presses the lever 9 of remote signalling of status on the detector 90, which emits a remote signal about change in status of overvoltage protection to show the status "not functioning - fallout".
In another not represented example of embodiment of the device for overvoltage protection as a device with two-stage signalling is the guiding groove 52 of shifting member 5 created as a straight one without shaping, by which the structure is simplified and the function for a two-stage signalling is preserved.
The invention is not limited only to the expressly here described or directly illustrated embodiments, but the modification of principle of gradual shifting of a single cut-off mechanism depending on temperature of varistor or varistors establishing gradually status signalling of partial and total degradation of overvoltage protection lies in the scope of skilled person in this technical field.

Industrial applicability

The invention is applicable for protection of electrical circuits against overvoltage.

List of reference marks

1: body of device for overvoltage protection
1 a: arm of device body for overvoltage protection
1 b: arm of device body for overvoltage protection
1 e: middle part of device body for overvoltage protection
1e0: circumferential wall of middle part of device body for overvoltage protection
1e1: window of visual signalling of status
1 e2: signalling surface of status "entirely functioning"
10: connecting terminal
11: wall of device body for overvoltage protection
12: wall at lower edge of device body for overvoltage protection
13: wall at lower edge of device body for overvoltage protection
4: non-linear resistance element
40: first electrode of non-linear resistance element
41: first electrically conductive joint
42: second electrode of non-linear resistance element
43: first low-melting electrically conductive joint
44: second electrically conductive member
440: first end of second electrically conductive member
441: second end of second electrically conductive member
442: bend of second electrically conductive member
45: angle cover plate
450: bent section of angle cover plate
46: second low-melting electrically conductive joint
47: gap
5: shifting member
50: stop end of shifting member
51: compression spring
52: guiding groove
520: first section of guiding groove
53: retaining recess
6: signalling lever
60: first pin of signalling lever
61: second pin of signalling lever
62: end for remote signalling of signalling lever
63: third pin of signalling lever
64: end for visual signalling of signalling lever
640: signalling surface of status "approaching fallout" and "not functioning - fallout"
7: shifting plate
70: guiding gap in shifting plate
71: askew surface on shifting plate
8: shifting pin
80: askew surface on shifting pin
81: flange on shifting pin
82: compression spring
9: lever of remote signalling of status
90: detector of extending the shifting pin

H: direction of height of device body for overvoltage protection
W: direction of width of device body for overvoltage protection

Claims

Device for overvoltage protection with protection status signalling, which comprises the spring-loaded shifting member (5), which in direction of its length is positioned displaceably and is provided with profiled guiding groove (52), into which engages the first pin (60) of signalling lever (6), which is provided with an end (64) for visual signalling in a window (1e1) in the body (1), at the same time the shifting member (5) acts by a pressing force upon the second electrically conductive member (44) and its first low-melting joint (43) with second electrode (42) of non-linear resistance element (4), while the second electrically conductive member (44) is further connected with connecting terminal (10) of the device, characterised in that, the shifting member (5) is by its length situated in direction (H) of height of the body (1) and on its end at the wall (11) of the body (1) it is provided with retaining recess (53) opened from above , the retaining recess (53) has a shorter length than the length of profiled guiding groove (52), and into the retaining recess (53) is extending the second pin (61) of signalling lever (6).
Device according to the claim 1, characterised in that, the profiled guiding groove (52) in its first section (520) comprises a lateral protrusion, while the distance of the lateral protrusion from beginning of the profiled guiding groove (52) corresponds in direction (H) of height of the body (1) to the length of retaining recess (53).
Device according to the claim 1 or 2, characterised in that, the shifting member (5) in its initial position is leaning against the bent section (450) of angle cover plate (45), which is by means of the second low-melting electrically conductive joint (46) mounted on the second electrically conductive member (44), while the second low-melting joint (46) has a lower melting temperature than is the melting temperature of the first low-melting electrically conductive joint (43).
Device according to any of the claims 1 to 3, characterised in that, the signalling lever (6) is provided with end (62) for remote signalling, on which is situated the pin (63), which extends into the guiding gap (70) in shifting plate (7), which is linear displaceably in direction (W) of width of the body (1) mounted in the body (1) at the lower edge of the body (1), and which is provided with askew surface (71), on which is by its askew face (80) sitting the hollow spring-loaded shifting pin (8), which is coupled with the lever (9) of remote signalling, to which there is assigned the detector (90) of pin extension (8).
Device according to the claim 4, characterised in that, the pin (8) is on its lower end provided with the flange (81), on whose upper side is in principle freely sitting one end of the lever (9) of remote signalling, the lever (9) is with its second end mounted in the body (1) in swivelling manner, while from upper side is to the lever (9) of remote signalling assigned a microswitch, which is electrically connected with remote place of remote signalling.