WO1993007667A1 - Dispositif de protection contre la surcharge et les courts-circuits dans des installations electriques - Google Patents
Dispositif de protection contre la surcharge et les courts-circuits dans des installations electriques Download PDFInfo
- Publication number
- WO1993007667A1 WO1993007667A1 PCT/SE1992/000696 SE9200696W WO9307667A1 WO 1993007667 A1 WO1993007667 A1 WO 1993007667A1 SE 9200696 W SE9200696 W SE 9200696W WO 9307667 A1 WO9307667 A1 WO 9307667A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- thermistor
- polymer composition
- electrodes
- pressure
- current
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
- H02H9/026—Current limitation using PTC resistors, i.e. resistors with a large positive temperature coefficient
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
- H01C7/02—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient
- H01C7/027—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient consisting of conducting or semi-conducting material dispersed in a non-conductive organic material
Definitions
- the present invention relates to a device for overload and short-circuit protection in electric plants .
- the device comprises a circuit breaker and a current limiter arranged in series with the circuit breaker and comprising at least two parallel-connected current branches, of which one branch comprises a thermistor with a positive temperature coefficient, and the other comprises an impedance for current and voltage relief of the thermistor upon a short circuit.
- the protection device is primarily intended for use in low-voltage plants by which is meant here plants with an operating voltage of at most 1000 V.
- a device of the above-mentioned kind which includes a ther ⁇ mistor of a ceramic type, is previously known from patent publication DE-A-2 510 322.
- a disadvantage of ceramic ther ⁇ mistors is that they exhibit a negative temperature coeffi ⁇ cient when the temperature exceeds a certain value.
- a ceramic thermistor will easily crack if traversed by a short-circuit current because of the thermal and mechani ⁇ cal stress to which it is subjected when it changes to its high-resistance state. In addition, it is relatively expen ⁇ sive.
- thermoelectric sensors intended for overcurrent protec ⁇ tion
- Thermistors of this type are composed of a polymeric material, for example high-pressure polyethylene, containing particles of an electrically con ⁇ ductive material, for example carbon black.
- a polymer-based thermistor of the above-mentioned kind possesses several advantages compared with a ceramic one. For example, its resistance in the temperature range in question increases monotonously with the temperature and the resistance increase is considerably greater. In addition, it is much less expensive.
- thermistors of the polymer-based type a disadvantage with hitherto known thermistors of the polymer-based type is that the resistance of such a thermistor, after having changed from a low- resistance to a high-resistance state, does not return to the initial resistance.
- the thermistor is subjected to very great electrical stresses, such as short-circuit currents, the formation of blisters and cracks occurs in the central or other parts of the polymer composition of the thermistor so that it can no longer operate, that is, the thermistor is destroyed.
- the aim has been to secure the electrodes as efficiently as possible to the body of polymer composition to achieve the best possible electrical contact and hence minimize the transition resis ⁇ tance.
- they are normally designed with an uneven surface structure on the side which faces the body of polymer composition, such that the polymer composition during the manufacturing of the thermistor may melt and penetrate into cavities in the elec ⁇ trode surface.
- the electrodes usually consist of metal foils and are applied by being pressed onto the body during heating.
- the present invention aims to provide a relatively simple and inexpensive protective device of the above-mentioned kind r which is capable of breaking the highest short-circuit currents occurring in low-voltage networks and which does not have the above-mentioned disadvantages which previous protective devices with thermistors suffered from.
- This is achieved according to the invention by a device which exhibits the characteristic features described in claim 1.
- the protective device according to the present invention includes a polymer-based thermistor which, contrary to hitherto known thermistors of this kind, after changing from a low-resistance to a high-resistance state returns to the 5 initial resistance, and which is reusable also after having been subjected to short-circuit currents. Further, the thermistor changes its resistance at a lower energy development, that is, its current-limiting properties are improved.
- the above-mentioned result is obtained by effecting at least one electrical contact between an electrode and a body of electrically conductive polymer composition or between two bodies of electrically
- the pressure which is maintained on the electrodes perpen ⁇ dicularly to the parallel surfaces of the body or bodies of polymer composition preferably amounts to at least 0.1 MPa. Especially preferred is a pressure of 0.1 MPa-10 MPa.
- Figure 1 shows a circuit diagram for a protective device * . according to the invention
- Figure 2 shows a curve of the resistance versus the tempe ⁇ rature for a thermistor included in the protective device according to Figure 1
- Figures 3 and 4 show in cross section two different thermis ⁇ tors consisting of two electrodes and one and two bodies, respectively, of electrically conductive polymer composition between the electrodes,
- Figures 5 and 6 show in cross section two different embodi ⁇ ments of a thermistor, provided with a pressure device, of the type which is included in the pro ⁇ tective device according to Figure 1,
- Figure 7 shows the variation of the current during a short- circuit breaking with a protective device accor ⁇ ding to Figure 1,
- Figures 8a, 8b and 8c show in perspective different parts of a current limiter included in the protective device according to Figure 1, in dismantled condition,
- Figure 9 shows in perspective part of the same device in a vertical section
- FIGS 10 and 11 show circuit diagrams for additional variants of the current limiter included in the protective device according to the invention.
- the device for overcurrent and short-circuit protection shown in Figure 1 comprises a circuit breaker and a current limiter connected in series with the circuit breaker.
- the circuit breaker may, for example, consist of a so-called automatic fuse, also called MCB (Miniature Circuit Breaker) or midget circuit breaker, with a rated current of, for example, 63 A.
- the circuit breaker comprises a contact device 1, a bimetallic tripping device 2 adapted to initiate the opening of the contact device at moderate overcurrents as well as an instantaneous tripping device 3 in the form of a percussion armature magnet (a so-called kicker) to influence the contact device directly at a short-circuit current.
- the current limiter comprises a thermistor 4 with a positive temperature coefficient (PTC element) connected in parallel with an impedance 5, which in the embodiment shown consists of a linear resistor with a resistance of, for example, 100 m ⁇ ,
- Thermistor 4 is of the above-mentioned polymer-based type.
- Figure 2 shows the resistance R for such a thermistor versus the temperature T.
- the resistance In the normal operating range of the thermistor, which may extend up to, for example, 80°C, the resistance is low, for example 3 m ⁇ , and increases slightly with the temperature. If the temperature of the thermistor rises above the mentioned value, for example because of an overcurrent, the resistance increases more rapidly, and when exceeding a certain temperature T , referred to below as the transition temperature, which, for example, may lie at about 120°C, the thermistor suddenly changes from a low-resistance to a high-resistance state, in which the resistance amounts to, for example, 150 m ⁇ .
- the thermistor according to Figure 3 comprises a centrally arranged body 10 of an electrically conductive polymer composition with a positive temperature coefficient, for example consisting of 67 per cent by volume polyethylene and 33 per cent by volume carbon black, in the form of a rec ⁇ tangular 1 mm thick disc as well as two electrodes 11 and 12, arranged at the parallel end surfaces 10' and 10" of the body (the flat sides of the disc) , with associated terminals 13 and 14, respectively.
- the electrode 11 consists of an 0.5 mm thick plate of nickel with an even surface structure on both sides. On its outside the plate is coated with a thin layer of copper. It makes contact with the body 10 only by abutting against the body, that is, it is not fixed to the body.
- the electrode 12 consists of an 0.3 mm thick copper foil which, on its side facing the body 10, is coated with an 0.1 mm thick layer of copper with uneven surface struc- ture, which layer is applied by plasma spraying.
- the elec ⁇ trode 12 is fixed to the polymer by pressing it against the body 10 after the body has been heated such that the polymer material in liquid state may penetrate into irregularities on the inwardly-facing side of the electrode.
- the device according to Figure 4 includes two bodies, 10a and 10b, of the same electrically conductive polymer compo ⁇ sition as that in body 10 in Figure 3, in the form of 1 mm thick rectangular discs with the parallel surfaces 10a',
- the electrodes 11 and 12 may be of the same kind as the electrodes 11 and 12 in Figure 3. However, the electrode 11 may also be of the same kind as the electrode 12 and, like this electrode, be fixed to the body 10a.
- the bodies 10a and 10b may be of different electrically conduc ⁇ tive polymer compositions and have different resistivities to modify the properties of the thermistor.
- the device may also be modified so as to comprise more than two bodies (10a and 10b) of conductive polymer composition with the same or a different resistivity.
- the electrodes are fixed to adjacent bodies or electrically conductive polymer composi- tion, at least one of the bodies must make free contact with another one of the bodies. If one of or both of the elec ⁇ trodes make free contact with an adjacent body of electri ⁇ cally conductive polymer composition, all the polymer bodies may be fixed to each other, for example by fusion.
- FIG 5 illustrates a device according to the invention in which a thermistor according to Figure 3 is arranged in a pressure device comprising two plates 15, 16, which are parallel to the parallel end surfaces of the body 10 (the flat sides of the disc 10) and to the electrodes 11 and 12.
- the terminals 13 and 14 are not shown in the figure.
- the plates are of electrically insulating material, for example resin reinforced with glass fibre.
- the pressure against the electrodes and against the end surfaces of the body 10 is brought about by tightening a number of bolts 17.
- stiff springs 17b are arranged which are not com- pletely compressed when the thermistor is pressurized and prepared for normal operation. In case of a short circuit, the springs may therefore be further compressed, which permits the electrode 11 to be separated from the body 10.
- the device according to Figure 6 differs from the device according to Figure 5 in that the springs 17a are not included and in that a 1 mm thick mat 30 of rubber is arranged between the electrode 11 and the plate 15. Such a mat of rubber may possibly be arranged between the electrode 12 and the plate 16 as well.
- a thermis ⁇ tor according to Figure 4 may be arranged, in an analogous manner, in the devices according to Figures 5 and 6.
- Figure 7 shows the variation of the current during a short- circuit breaking with a protective device according to Figure 1 at a network voltage of 500 V and a network short- circuit current of 30 kA.
- the thermistor 4 (Fig. 1) has a low resistance, for example 3 m ⁇ , and the entire operating current flows therethrough. If a short circuit occurs, the current rises very rapidly, and even after about 1 ms from the occurrence of the short circuit (Fig. 7), the thermistor trips (i.e. changes from a low- resistance to a high-resistance state) . This causes a very fast limitation of the current, which is for the main part commutated over to the parallel resistor 5, which has a resistance of about 100 m ⁇ .
- the thermistor is relieved of both current and voltage, whereby breakdown of the polymer material in the thermistor is avoided.
- the contact device 1 is opened by the action of the percussion armature magnet 3, whereby the current is broken after about 5 ms from the instant of short circuit. Since the current is limited to a relatively low value because of the current limiter 4, 5 and, in addition, is substantially resistive, the breaking is relatively easy. Through the contact opening a rapid voltage relief of the thermistor 4 is obtained, and there ⁇ fore the thermistor need not be designed to continuously withstand the operating voltage.
- a feasible explanation of the result obtained with the protective device according to the invention may be the following.
- the heating of the polymer composition is concen ⁇ trated at the initial stage substantially at contact sur ⁇ faces between those elements in the thermistor which make contact with each other, since the resistance is higher at the transition between the elements than in the polymer composition itself. This leads to the formation of gas in the material surface with ensuing pressure build-up between the elements, which, in addition, are influenced by electro- dynamic repulsion forces.
- the device according to Figures 8a, b, c and 9 comprises three identical thermistors, one of which being shown with the parts separated in Figure 8b.
- the body 10 of electri ⁇ cally conductive polymer composition for example of the same kind as in Figure 3, is arranged in a plastic frame 40 which extends around the body.
- the two electrodes 11 and 12 consist of 1 mm thick silver-plated plates of copper which make contact with the body 10. only by abutting against it, that is, they are not fixed to the body.
- Each electrode is provided with alternative conductor terminals 13a and 14a for cable connection and 13b (not shown) and 14b, respec- tively, for connection to a busbar.
- a package comprising the plates 41 and 42 and electrodes 11 and 12 arranged therebetween as well as with an intermediate body 10 of conductive polymer composition is arranged in each of three compartments 43a, 43b and 43c in an apparatus housing 43 with two intermediate walls 43d and 43e which form the compartments.
- the intermediate walls are parallel to two opposite parallel walls 43f and 43g in the apparatus housing.
- the apparatus housing is provided with recesses 44a and 44b for alternative connection of a conductor to the attachment 14a or 14b in the compartment 43a, with recesses 45a and 45b for alternative connection of a conductor to the attachment 14a or 14b in the compartment 43b, and with recesses 46a and 46b for alternative connection of a conduc- tor to the attachment 14a or 14b on an electrode 12 in the compartment 43c.
- recesses 44a and 44b for alternative connection of a conductor to the attachment 14a or 14b in the compartment 43a
- recesses 45a and 45b for alternative connection of a conductor to the attachment 14a or 14b in the compartment 43b
- recesses 46a and 46b for alternative connection of a conduc- tor to the attachment 14a or 14b on an electrode 12 in the compartment 43c.
- On the opposite, not visible wall of the apparatus housing there are corresponding recesses for the connection of conductors to attachments 13a and 13b on each electrode 11.
- the pressure between the electrodes 11 and 12 and the body in each one of the packages in the compartments 43a, 43b and 43c is effected by applying on the apparatus housing a cover 47 with wedge-shaped plates 48, 49 and 50 fixed on the cover, each of the wedge-shaped plate thus being inserted into a respective one of the compartments 43a, 43b and 43c until contact is made with a plate 41 located there.
- the cover is arranged with mechanical attachments 47a, 47b, 47c and 47d for mounting.
- the apparatus housing is provided with plane-parallel reinforcement walls 51 and 52 on the pressure-absorbing sides.
- the device according to Figures 8a, b, c and 9 is intended to be connected into a three- phase line with a thermistor connected into each of the three phase conductors.
- the apparatus housing 43 with intermediate walls 43f and 43g, reinforcement walls 51 and 52, cover 47 and wedge-shaped plates 41, 48, 49 and 50 are all made of an electrical insulating material, for example polyamide, provided with a filler, for example in the form of short glass fibres.
- the impedance for current and voltage relief of the thermistor 4 need not necessarily consist of a linear resistor 5, but several other variants are possible.
- Figure 10 shows a second embodiment in which the thermistor 4 is connected in parallel with a voltage-dependent resistor 6, preferably in the form of a ZnO varistor.
- Figure 11 shows a third embodiment in which the thermistor 4 is connected in parallel with a second thermistor 7 with a higher initial resistance, for example 10-50 m ⁇ , and with a relief resistor 5, which may be linear or voltage-dependent.
- the relief impedance may also consist of a thermistor with a negative temperature coefficient (NTC element) .
- NTC element negative temperature coefficient
- at least the electrodes 11, 12 of the thermistor 4 are provided with cooling means, for example in the form of cooling flanges, which are then arranged thermally connected but electrically insulated from the electrodes.
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- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Chemical & Material Sciences (AREA)
- Dispersion Chemistry (AREA)
- Ceramic Engineering (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Power Engineering (AREA)
- Thermistors And Varistors (AREA)
Abstract
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP5506842A JPH06511617A (ja) | 1991-10-07 | 1992-10-05 | 電気設備の過負荷および短絡防護装置 |
EP92921495A EP0607269A1 (fr) | 1991-10-07 | 1992-10-05 | Dispositif de protection contre la surcharge et les courts-circuits dans des installations electriques |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE9102895-1 | 1991-10-07 | ||
SE9102895A SE469250B (sv) | 1991-10-07 | 1991-10-07 | Anordning foer oeverlast- och kortslutningsskydd i elektriska anlaeggningar |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1993007667A1 true WO1993007667A1 (fr) | 1993-04-15 |
Family
ID=20383921
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/SE1992/000696 WO1993007667A1 (fr) | 1991-10-07 | 1992-10-05 | Dispositif de protection contre la surcharge et les courts-circuits dans des installations electriques |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0607269A1 (fr) |
JP (1) | JPH06511617A (fr) |
SE (1) | SE469250B (fr) |
WO (1) | WO1993007667A1 (fr) |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0655760A2 (fr) * | 1993-11-30 | 1995-05-31 | ABBPATENT GmbH | Dispositif interrupteur électrique |
EP0713227A1 (fr) * | 1994-11-19 | 1996-05-22 | ABB Management AG | Thermistance et dispositif de limitation de courant avec au moins une thermistance |
FR2738681A1 (fr) * | 1995-09-12 | 1997-03-14 | Gec Alsthom T & D Sa | Limiteur de courant a polymere |
EP0786832A1 (fr) * | 1995-08-11 | 1997-07-30 | Maspro Denkoh Co., Ltd. | Dispositif de derivation |
US5666254A (en) * | 1995-09-14 | 1997-09-09 | Raychem Corporation | Voltage sensing overcurrent protection circuit |
US5689395A (en) * | 1995-09-14 | 1997-11-18 | Raychem Corporation | Overcurrent protection circuit |
US5737160A (en) * | 1995-09-14 | 1998-04-07 | Raychem Corporation | Electrical switches comprising arrangement of mechanical switches and PCT device |
US5864458A (en) * | 1995-09-14 | 1999-01-26 | Raychem Corporation | Overcurrent protection circuits comprising combinations of PTC devices and switches |
FR2772524A1 (fr) * | 1997-12-12 | 1999-06-18 | Legrand Sa | Dispositif de protection contre des surintensites, notamment pour la protection rearmable d'un interrupteur controle |
EP3416179A1 (fr) * | 2017-06-16 | 2018-12-19 | Schneider Electric Industries SAS | Appareil de protection électrique comportant un dispositif limiteur de courant |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
SE515262C2 (sv) * | 1995-02-16 | 2001-07-09 | Abb Research Ltd | Anordning för strömbegränsning och skydd mot kortslutningsströmmar i en elektrisk anläggning |
US10895609B2 (en) * | 2019-05-09 | 2021-01-19 | Littelfuse, Inc. | Circuit protection device with PTC element and secondary fuse |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4656555A (en) * | 1984-12-14 | 1987-04-07 | Harvey Hubbell Incorporated | Filament wrapped electrical assemblies and method of making same |
US4698614A (en) * | 1986-04-04 | 1987-10-06 | Emerson Electric Co. | PTC thermal protector |
EP0363746A1 (fr) * | 1988-10-13 | 1990-04-18 | Asea Brown Boveri Ab | Dispositif de protection contre les surintensités pour réseaux électriques et appareils |
-
1991
- 1991-10-07 SE SE9102895A patent/SE469250B/sv not_active IP Right Cessation
-
1992
- 1992-10-05 JP JP5506842A patent/JPH06511617A/ja active Pending
- 1992-10-05 EP EP92921495A patent/EP0607269A1/fr not_active Withdrawn
- 1992-10-05 WO PCT/SE1992/000696 patent/WO1993007667A1/fr not_active Application Discontinuation
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4656555A (en) * | 1984-12-14 | 1987-04-07 | Harvey Hubbell Incorporated | Filament wrapped electrical assemblies and method of making same |
US4698614A (en) * | 1986-04-04 | 1987-10-06 | Emerson Electric Co. | PTC thermal protector |
EP0363746A1 (fr) * | 1988-10-13 | 1990-04-18 | Asea Brown Boveri Ab | Dispositif de protection contre les surintensités pour réseaux électriques et appareils |
Cited By (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0655760A3 (fr) * | 1993-11-30 | 1997-06-04 | Abb Patent Gmbh | Dispositif interrupteur électrique. |
EP0655760A2 (fr) * | 1993-11-30 | 1995-05-31 | ABBPATENT GmbH | Dispositif interrupteur électrique |
US6094129A (en) * | 1994-11-19 | 2000-07-25 | Daimlerchrysler Ag | PTC thermistor and a current limiter device having at least one PTC thermistor |
EP0713227A1 (fr) * | 1994-11-19 | 1996-05-22 | ABB Management AG | Thermistance et dispositif de limitation de courant avec au moins une thermistance |
KR100391961B1 (ko) * | 1994-11-19 | 2003-10-30 | 다임러크라이슬러 레일 시스템즈 게엠베하 | Ptc서미스터및하나이상의ptc서미스터를갖는전류리미터장치 |
EP0786832A1 (fr) * | 1995-08-11 | 1997-07-30 | Maspro Denkoh Co., Ltd. | Dispositif de derivation |
EP0786832A4 (fr) * | 1995-08-11 | 1998-10-28 | Maspro Denkoh Co Ltd | Dispositif de derivation |
FR2738681A1 (fr) * | 1995-09-12 | 1997-03-14 | Gec Alsthom T & D Sa | Limiteur de courant a polymere |
US5689395A (en) * | 1995-09-14 | 1997-11-18 | Raychem Corporation | Overcurrent protection circuit |
US5737160A (en) * | 1995-09-14 | 1998-04-07 | Raychem Corporation | Electrical switches comprising arrangement of mechanical switches and PCT device |
US5864458A (en) * | 1995-09-14 | 1999-01-26 | Raychem Corporation | Overcurrent protection circuits comprising combinations of PTC devices and switches |
US5666254A (en) * | 1995-09-14 | 1997-09-09 | Raychem Corporation | Voltage sensing overcurrent protection circuit |
FR2772524A1 (fr) * | 1997-12-12 | 1999-06-18 | Legrand Sa | Dispositif de protection contre des surintensites, notamment pour la protection rearmable d'un interrupteur controle |
WO1999031778A1 (fr) * | 1997-12-12 | 1999-06-24 | Legrand | Dispositif de protection contre des surintensites, notamment pour la protection rearmable d'un interrupteur controle |
US6342994B1 (en) | 1997-12-12 | 2002-01-29 | Legrand | Protective device against excessive currents, in particular for resettable protection of a controlled switch |
EP3416179A1 (fr) * | 2017-06-16 | 2018-12-19 | Schneider Electric Industries SAS | Appareil de protection électrique comportant un dispositif limiteur de courant |
FR3067870A1 (fr) * | 2017-06-16 | 2018-12-21 | Schneider Electric Industries Sas | Appareil de protection electrique comportant un dispositif limiteur de courant |
US10741350B2 (en) | 2017-06-16 | 2020-08-11 | Schneider Electric Industries Sas | Electrical protection unit including a current limiter device |
Also Published As
Publication number | Publication date |
---|---|
JPH06511617A (ja) | 1994-12-22 |
EP0607269A1 (fr) | 1994-07-27 |
SE469250B (sv) | 1993-06-07 |
SE9102895D0 (sv) | 1991-10-07 |
SE9102895L (sv) | 1993-04-08 |
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