EP2919254B1

EP2919254B1 - Surge protection device having short-circuit current protection function

Info

Publication number: EP2919254B1
Application number: EP12887906.1A
Authority: EP
Inventors: Tianwen YIN; Yang Cao; Biyun WANG; Renjie LI; Niansheng XU; Cangwei YAN
Original assignee: Zhejiang Chint Electrics Co Ltd; SEARI Electric Technology Co Ltd
Current assignee: Zhejiang Chint Electrics Co Ltd; SEARI Electric Technology Co Ltd
Priority date: 2012-11-12
Filing date: 2012-11-12
Publication date: 2020-02-26
Anticipated expiration: 2032-11-12
Also published as: CN104813432A; EP2919254A1; CN106783431A; CN106783431B; CY1123104T1; WO2014071628A1; CN104813432B; EP2919254A4; ES2791039T3

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to over voltage protection in low voltage distribution system, more particularly, to a surge protection device with short-circuit current protection function.

2. The Related Art

Because of the factors such as current impacts, frequency voltage fluctuation and environment temperature change, elements in voltage limiting type SPD, such as piezoresistors will meet degradation or short-circuit malfunction, which may result in failures such as overheat, short-circuit or electric shock. Such failures may threaten the surrounding people or articles, or even the system itself. Therefore, voltage limiting type SPDs must have degradation or short-circuit protection, that means, voltage limiting type SPDs shall have releases for preventing thermal breakdown (i.e. providing thermal protection) or short-circuit malfunctions (i.e. providing short-circuit protection). When degradation or short-circuit malfunction occurs in a voltage limiting type SPD, the release may disconnect the SPD from a system, so that the malfunction will not propagate to the system or cause a fire.
In existing protection techniques for voltage limiting SPDs, external connected overcurrent protection elements are usually used as releases for preventing thermal breakdown. The overcurrent protection elements include breakers, fuses or residual current operated protective devices (RCD). The external overcurrent protection elements are designed based on power frequency characteristics and do not have corresponding surge performance indexes, thus the power frequency performance and the surge performance may not match in actual applications. Possible results of such mismatch include: the external overcurrent protection element is not able to bear the surge impact which is matched to the voltage limiting type SPD; or an overall residual voltage Up value of a combination of the overcurrent protection element and the SPD is not able to be determined. Such problems will influence the safety and protection effect of the voltage limiting SPDs.
The Chinese patent application CN 101 320 658 A , entitled "surge protection device with backup protection" discloses a surge protection device according to the preamble of claim 1, with backup protection. The surge protection device integrates a short-circuit protection component and a surge protection component, and overcomes the problem of high residual voltage brought by using an external overcurrent protection device as backup protection for a voltage limiting type SPD.
However, the SPD disclosed in this application still have some drawbacks, for example: 1) the current capacity is small; 2) the short-circuit breaking capacity is low; 3) a protection to a small multiple overload current is not provided and the protection range is narrow; 4) the reliability of the short-circuit protection device is not high; 5) a protection under temporary overvoltage (TOV) caused by a system malfunction due to large capacity surge current impact is not considered; 6) an overall volume of the product is large.

SUMMARY

The present invention relates to a voltage limiting type surge protection device with short-circuit protection function, as defined in appended claim 1.
Such a surge protection device comprises a surge protection module and a short-circuit current protection module. The surge protection module discharges and suppresses a surge current and voltage and the surge protection module is a plug-in type module. The short-circuit current protection module has short-circuit protection function and is integrated in a pedestal. The short-circuit protection module is recoverable and provides short-circuit protection and plug-in mounting for the surge protection module.
In an embodiment, the short-circuit protection module comprises: a base and a lid, a moving contact and a static contact, a lightning sensitive switch, an electromagnetic mechanism, an elastic connection piece, a baffle plate, a first connection terminal, a second connection terminal, a first elastic plug and a second elastic plug. The lid covers the base to form a housing of the pedestal. The static contact includes a bracket. The lightning sensitive switch is connected to the static contact and the elastic connection piece. The electromagnetic mechanism includes an iron yoke and a coil. The elastic connection piece includes an elastic terminal, an upper curved extension part and a lower extension part. The baffle plate is mounted on the base, the baffle plate and the base forms a self-extinguishing arc extinguishing chamber. The first connection terminal is connected to an external phase line. The second connection terminal is connected to an external phase line or a ground line. The first elastic plug and the second elastic plug is connected to the surge protection module, the first elastic plug is connected to the first connection terminal and the second elastic plug is connected to the second connection terminal.
In an embodiment, the bracket of the static contact is a U shaped static bracket so as to ensure that the direction of a current flowing through the static contact is consistent with the direction of a current flowing through the moving contact.
In an embodiment, a high resistance coil with a resistance larger than 200m Ω is used to provide a high current limiting capacity. The lightning sensitive switch is connected in parallel with the high resistance coil and a first end of the lightning sensitive switch is connected to bracket of the static contact.
In an embodiment, the second end of the lightning sensitive switch is connected to an elastic terminal of the elastic connection piece, the elastic connection piece provides an elastic force for pressing the lightning sensitive switch. An upper extension part of the bracket of the static contact is welded to a first end of the coil at an extension part of the iron yoke. The upper curved extension part of the elastic connection piece is welded to a second end of the coil, the lower extension part of the elastic connection piece is connected to a first elastic plug through a connection piece.
In an embodiment, a ladder shaped grates is disposed on the baffle plate.
In an embodiment, the moving contact is made of silver tungsten alloy material, the static contact is made of silver tungsten carbide alloy material.
In an embodiment, the lightning sensitive switch is a ceramic gas discharge tube with a nominal DC breakdown voltage higher than 250V.
In an embodiment, the short-circuit current protection module further comprises a handle, an operation mechanism, a block plate and a remote alarm device which is optionally installed.
In an embodiment, the surge protection module comprises a first plug plate and a second plug plate, the first plug plate and the second plug plate are plugged with the first elastic plug and the second elastic plug.
In an embodiment, an overall width of the product is 27mm or 36mm, a width of the surge protection module is 9mm or 18mm. The surge protection module has convex edges with different heights on both sides, the short-circuit current protection module has grooves with corresponding heights on corresponding surfaces, so that plug operations in error may be avoided.
The surge protection device with short-circuit protection function of the present invention has the following advantages:

1) The problem of coordination between a lightning impact current and a power frequency short-circuit current is solved, and the overall circuit has a high current limiting capacity. High resistance resistors with positive temperature coefficient, such as a high resistance coil with a resistance higher than 200m Ω is preferred. The surge protection device has a strong current limiting capacity, in other words, a strong short-circuit current protection capacity and a good short-circuit breaking capacity.
2) The surge protection device provides protection to a small multiple overload current. The minimal short-circuit current that can be protected is 10A. The surge protection device provides protection to a broad range of short-circuit currents and may be applied to any type of grounding systems.
3) A recoverable temporary overvoltage (TOV) tolerance mode is provided, flaming under traditional TOV failure and tolerance mode is eliminated so as to avoid fire hazards. The product has a high safety reliability.
4) The principle of opening the contact in advance by an electrical force is changed, actions in error will not occur even under a large capacity lightning impact current, so the service life of the product is increased.
5) The residual voltage Up is controllable, a power frequency current and a surge current may be converted quickly through dual channels with high flexibility and high reliability. A frequency sensitive switch not only considers the system over voltage, but also the operation over voltage. An action in error of the lightning sensitive switch may be prevented so as to ensure the stability and a high short-circuit breaking capacity of the product.
6) Ablation resistant materials are used for contacts so as to increase the ablation resistance and anti-electrical wear ability. The contact pressure changes in a small range even under a large capacity lightning impact current.
7) The lightning sensitive switch is connected in a manner of elastic connection, so that the integrity of the lightning sensitive switch during assembly is guaranteed and the assembly process is facilitated.
8) The attraction of contacts with a same direction of currents and a high resistance resistor with positive temperature coefficient may reduce the requirements of arc extinction. Gas channels are enlarged to facilitate the gas exclusion, gas quenching is utilized such that the volume of the product is smaller.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features, natures, and advantages of the invention will be apparent by the following description of the embodiments incorporating the drawings, wherein,

Fig. 1 illustrates an overall structural diagram of a surge protection device with short-circuit current protection function according to an embodiment of the present invention.
Fig. 2 illustrates a structural diagram of a surge protection module in the surge protection device with short-circuit current protection function according to an embodiment of the present invention.
Fig. 3 illustrates a structural diagram of the surge protection module mounting to a pedestal in the surge protection device with short-circuit current protection function according to an embodiment of the present invention.
Fig. 4 illustrates a structural diagram of a short-circuit current protection module in the surge protection device with short-circuit current protection function according to an embodiment of the present invention.
Fig. 5 illustrates a structural diagram of a baffle plate of the short-circuit current protection module in the surge protection device with short-circuit current protection function according to an embodiment of the present invention.
Fig. 6 illustrates a structural diagram of a self-extinguishing arc extinguishing chamber of the short-circuit current protection module in the surge protection device with short-circuit current protection function according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

The present invention discloses a surge protection device with short-circuit protection function. The surge protection device comprises a surge protection module and a short-circuit current protection module. The surge protection module discharges and suppresses a surge current and voltage and the surge protection module is a plug-in type module. The short-circuit current protection module is integrated in a pedestal and provides short-circuit protection and plug-in mounting for the surge protection module.
The short-circuit current protection module comprises: a base and a lid, a moving contact and a static contact, a lightning sensitive switch, an electromagnetic mechanism, an elastic connection piece, a baffle plate, a first connection terminal, a second connection terminal, a first elastic plug and a second elastic plug. The lid covers the base to form a housing of the pedestal. The static contact includes a bracket which is a U shaped static bracket. The electromagnetic mechanism includes an iron yoke and a coil, the coil is connected to a high resistance resistor with a resistance larger than 200m Ω. The electromagnetic mechanism has a strong current limiting capacity. The lightning sensitive switch is connected to the static contact and the elastic connection piece. The lightning sensitive switch is connected in parallel with the coil. A first end of the lightning sensitive switch is connected to the bracket of the static contact. A second end of the lightning sensitive switch is connected to an elastic terminal of the elastic connection piece. The elastic connection piece provides an elastic force for pressing the lightning sensitive switch. An upper extension part of the bracket of the static contact is welded to a first end of the coil at an extension part of the iron yoke. An upper curved extension part of the elastic connection piece is welded to a second end of the coil. A lower extension part of the elastic connection piece is connected to the first elastic plug through a connection piece. The elastic connection piece includes an elastic terminal, an upper curved extension part and a lower extension part. The baffle plate is mounted on the base and a ladder shaped grate is disposed on the baffle plate, so that the baffle plate and the base form a self-extinguishing arc extinguishing chamber. The first connection terminal is connected to an external phase line. The second connection terminal is connected to an external phase line or a ground line. The first elastic plug and the second elastic plug are connected to the surge protection module. The first elastic plug is connected to the first connection terminal and the second elastic plug is connected to the second connection terminal.
The moving contact is made of silver tungsten alloy material. The static contact is made of silver tungsten carbide alloy material. The lightning sensitive switch is a ceramic gas discharge tube with a nominal DC breakdown voltage higher than 250V. The short-circuit current protection module further includes a handle, an operation mechanism, a block plate and a remote alarm device which is optionally installed.
The surge protection module includes a first plug plate and a second plug plate. The first plug plate and the second plug plate are plugged with the first elastic plug and the second elastic plug. An overall width of the product is 27mm or 36mm. A width of the surge protection module is 9mm or 18mm. The surge protection module has convex edges on both sides and the short-circuit current protection module has grooves on corresponding surfaces.
The surge protection device with short-circuit protection function of the present invention has the following characteristics:

1) High resistance resistors with positive temperature coefficient are used to enhance the short-circuit current protection. A high resistance coil with a resistance higher than 200m Ω is used so the product has a good short-circuit breaking capacity. The electromagnetic mechanism may act under a small failure current. The product has a small minimal instantaneous tripping current value, provides protection to a broad range of short-circuit currents and may be applied to any type of grounding systems.
2) A recoverable temporary overvoltage (TOV) tolerance mode is provided, sparks or flaming is eliminated.
3) The currents flowing through the moving contact and the static contact have a same direction so that the electrical opening force is reduced. The bracket of the static contact has a U shaped static structure. The moving contact and a near side of the U shaped static bracket (mounted with the static contact) which is close to the moving contact will attract each other under the electrical force. When a large current capacity impact occurs, a response time of moving contact opening will be delayed and an impact force caused by moving contact opening is small, therefore the operation mechanism will not trip by mistake. Assisted by the high resistance current limiting and the design that the contacts may open only when the electromagnetic mechanism acts, the operation mechanism has a high stability.
4) The lightning sensitive switch in a frequency sensitive current conversion switch is disposed in such a manner that, when a surge current intrudes, the surge current is discharged by the lightning sensitive switch first. The current after discharge then flows through the coil, thus the surge energy born by the coil and the high resistance resistor is significantly decreased. The surge bearing capacity of the short-circuit protection module is increased.
5) A self-extinguishing arc extinguishing chamber is formed within the product to replace an original coupled interrupter, so that the volume of the product is reduced. The self-extinguishing arc extinguishing chamber is formed as follows: a ladder shaped grate is designed on the elements, after assembly, a semi-hermetic interrupter forms around a position where the moving contact and the static contact close or open, and the moving contact and the static contact are completely surrounded by the interrupter. Because of the current limiting by the high resistance resistor, when the moving contact opens, the arc current is not so large even under a large failure current, the arc is extinguished at the first time by gas quenching.
6) The moving contact is made of silver tungsten alloy material. The static contact is made of silver tungsten carbide alloy material.
7) The nominal DC breakdown voltage of the lightning sensitive switch is higher than 250V.
8) The surge protection module may prevent plug in error.

Fig. 1 ∼ Fig. 6 illustrate the structural diagrams of an surge protection device with short-circuit current protection function according to an embodiment of the present invention. As shown in Fig. 1 ∼ Fig. 6, the surge protection device 100 with short-circuit current protection function solves the problems brought by using an external overcurrent protection device as backup protection. The surge protection device 100 with short-circuit current protection function includes a short-circuit current protection module 101 and a surge protection module 102. The short-circuit current protection module 101 is used to protect the surge protection module 102. The surge protection module 102 is used to discharge and suppress a surge current and voltage. The short-circuit current protection 101 is integrated in a pedestal for mounting the surge protection module 102. The surge protection module 102 is plug-in type.
The short-circuit current protection module 101 comprises a base 103, a lid 105, a moving contact 106, a static contact 107, a lightning sensitive switch 108, an electromagnetic mechanism 109, a handle 110, an operation mechanism 111, an elastic connection piece 112, a baffle plate 113, a block plate 114, a first connection terminal 115, a second connection terminal 116, a first elastic plug 117, a second elastic plug 118 and a remote alarm device 104, the remote alarm device 104 is optionally installed.
The lid 105 covers the base 103 to form a housing of the pedestal, that is, the housing of the surge protection module 102. The static contact 107 includes a bracket 107a. The bracket 107a is a U shaped static bracket using a U shaped static structure so as to ensure that the direction of a current flowing through the static contact 107 is consistent with the direction of a current flowing through the moving contact 106. Thus, the moving contact 106 and a near side of the U shaped static bracket (mounted with the static contact) which is close to the moving contact will attract each other under the electrical force. When a large current capacity impact occurs, a response time of moving contact opening will be delayed and an impact force caused by moving contact opening is small, therefore the operation mechanism 111 will not trip by mistake.
The electromagnetic mechanism 109 includes an iron yoke 109a and a coil 109b. The coil 109b includes a high resistance resistor and the high resistance resistor performs current limiting for the coil 109b. The resistance of the high resistance resistor is larger than 300m Ω. The number of windings of the coil 109b is larger than 100 turns, which may facilitate the actions of the electromagnetic mechanism under a low fault current while ensuring a high breaking capacity of the short-circuit protection module.
The lightning sensitive switch 108 is connected in parallel with the coil 109b of the electromagnetic mechanism in electrical connection. Further, a first end of the lightning sensitive switch 108 is connected to the U shaped static bracket 107a of the static contact 107. A second end of the lightning sensitive switch 108 is connected to an elastic terminal of the elastic connection piece 112. The elastic connection piece 112 provides an elastic force for pressing the lightning sensitive switch 108. The elastic connection piece 112 includes an elastic terminal, an upper curved extension part and a lower extension part. An upper extension part of the U shaped static bracket 107a, on which the static contact 107 is mounted, is welded to a first end of the coil 109b at an extension part of the iron yoke 109a. The upper curved extension part of the elastic connection piece 112 is welded to a second end of the coil 109b. The lower extension part of the elastic connection piece 112 is connected to a first elastic plug 117 through a connection piece 119. In such a connection type, the lightning sensitive switch is disposed in front of the coil of the electromagnetic mechanism in electrical route. More particularly, when a surge current intrudes, the surge current is discharged by the lightning sensitive switch first. The current after discharge then flows through the coil, thus the surge energy born by the coil and the high resistance resistor is significantly decreased. The surge bearing capacity of the short-circuit protection module is increased.
The base 103 and the baffle plate 113 are assembled and form a self-extinguishing arc extinguishing chamber 120 within the product. More particularly, a ladder shaped grate is disposed on the baffle plate 113, when the base 103 and the baffle plate 113 are assembled tightly, a semi-hermetic interrupter 120 forms around a position where the moving contact and the static contact close or open. The moving contact and the static contact are completely surrounded by the interrupter. When the moving contact opens and generates an arc, the arc is driven by the electrical force and moves downward along one side of the U shaped static bracket, the arc is directly cut by the ladder shaped grate at the first time and is extinguished.
The short-circuit current protection module 101 is integrated within the pedestal for mounting the surge protection module 102. The first connection terminal and the second connection terminal for connecting external lines are both disposed within the short-circuit current protection module. The first connection terminal 115 disposed within the short-circuit current protection module is used to connect an external phase line, and the second connection terminal 116 disposed within the short-circuit current protection module is used to connect an external phase line or a ground line. The first connection terminal 115 disposed within the short-circuit current protection module is connected to the first elastic plug 117 for mounting the surge protection module through a series of internal electrical connections, and the second connection terminal 116 disposed within the short-circuit current protection module is connected to the second elastic plug 118 for mounting the surge protection module, so that the short-circuit protection module provides backup protection to the surge protection module.
The surge protection module 102 is designed to have a plug-in structure, which may be replaced easily and quickly. The first plug plate 122 and the second plug plate 123 of the surge protection module 102 are plugged into the corresponding first elastic plug 117 and the second elastic plug 118 of the short-circuit current protection module respectively, so that the surge protection module and the short-circuit current protection module are connected to each other. The surge protection module has convex edges 121 with different heights on both sides, and the short-circuit current protection module has grooves corresponding to different heights on corresponding mounting surfaces, therefore the surge protection module may be mounted reliably and plug operations in error may be avoided.
The width of the surge protection module 102 is designed to be 9mm or 18mm, which complies to the international practice and may obtain a strong mounting compatibility.
The moving contact 106 is made of silver tungsten alloy material. The static contact 107b is made of silver tungsten carbide alloy material. The alloy material may attenuate the erosion of the moving contact and the static contact caused by the surge energy. The short-circuit current protection module still works after multiple impacts of large current capacity, the service life of the short-circuit current protection module is increased.
The lightning sensitive switch 108 is a switch element, and is preferred to be a gas discharge tube, such as a ceramic gas discharge tube. The nominal DC breakdown voltage of the ceramic gas discharge tube is higher than 250V.
The surge protection device with short-circuit protection function of the present invention has the following advantages:

The above embodiments are provided to those skilled in the art to realize or use the invention, under the condition that various modifications or changes being made by those skilled in the art without departing the scope of the invention, the above embodiments may be modified and changed variously, therefore the protection scope of the invention is not limited by the above embodiments, rather, it should conform to the scope defined by the appended claims.

Claims

A surge protection device (100) with short-circuit protection function, comprising:
a surge protection module (102) discharging and suppressing a surge current and voltage, the surge protection module being a plug-in type module;

a short-circuit current protection module (101) integrated in a pedestal and providing short-circuit protection and plug-in mounting for the surge protection module,

wherein the short-circuit current protection module (10) comprises:
a moving contact (106) and a static contact (107), the static contact including a bracket (107a);

an electromagnetic mechanism (109) including an iron yoke (109a) and a coil (109b); and

a lightning sensitive switch (108) connected to the static contact (107) and an elastic connection piece (112), the lightning sensitive switch (108) being connected in parallel with the coil (109b) and a first end of the lightning sensitive switch (108) being connected to the bracket (107a) of the static contact, characterised in that

the bracket (107a) is a U shaped static bracket and direction of a current flowing through the static contact is consistent with the direction of a current flowing through the moving contact, and in that the coil (109b) includes a resistor with positive temperature coefficient.
The surge protection device (100) with short-circuit protection function according to claim 1, wherein the short-circuit protection module (101) further comprises:
a base (103) and a lid (105), the lid covering the base to form a housing of the pedestal;

an elastic connection piece (112) including an elastic terminal, an upper curved extension part and a lower extension part;

a baffle plate (113) mounted on the base (103), the baffle plate and the base forming a self-extinguishing arc extinguishing chamber (120);

a first connection terminal (115) connected to an external phase line;

a second connection terminal (116) connected to an external phase line or a ground line;

a first elastic plug (117) and a second elastic plug (118) for connecting to the surge protection module (102), the first elastic plug (117) being connected to the first connection terminal (115) and the second elastic plug (118) being connected to the second connection terminal (116).
The surge protection device with short-circuit protection function according to claim 1 or 2, wherein
the resistor is a high resistance resistor with a resistance larger than 500m Q .
The surge protection device with short-circuit protection function according to claim 3, wherein
the second end of the lightning sensitive switch (108) is connected to an elastic terminal of the elastic connection piece (112), the elastic connection piece provides an elastic force for pressing the lightning sensitive switch;
an upper extension part of the bracket (107a) of the static contact is welded to a first end of the coil (109b) at an extension part of the iron yoke (109a);
the upper curved extension part of the elastic connection piece (112) is welded to a second end of the coil (109b), the lower extension part of the elastic connection piece (112) is connected to a first elastic plug through a connection piece.
The surge protection device with short-circuit protection function according to claim 2, wherein a ladder shaped grate is disposed on the baffle plate (113).
The surge protection device with short-circuit protection function according to any of claims 1 to 5, wherein
the moving contact (106) is made of silver tungsten alloy material;
the static contact (107) is made of silver tungsten carbide alloy material.
The surge protection device with short-circuit protection function according to any of claims 1 to 6, wherein
the lightning sensitive switch (108) is a ceramic gas discharge tube with a nominal DC breakdown voltage higher than 250V.
The surge protection device with short-circuit protection function according to any of claims 1 to 7, wherein the short-circuit current protection module (101) further comprises a handle (110), an operation mechanism (111), a block plate (114) and a remote alarm device (104) which is optionally installed.
The surge protection device with short-circuit protection function according to any of claims 1 to 8, wherein the surge protection module (102) comprises a first plug plate (122) and a second plug plate (123), the first plug plate (122) and the second plug plate (123) are plugged with the first elastic plug (117) and the second elastic plug (118).
The surge protection device with short-circuit protection function according to any of claims 1 to 9, wherein
a width of the surge protection module (102) is 9mm or 18mm;
the surge protection module (102) has convex edges with different heights on both sides, the short-circuit current protection module (101) has grooves with corresponding heights on corresponding surfaces.