GB2055264A - A circuit protection switch - Google Patents
A circuit protection switch Download PDFInfo
- Publication number
- GB2055264A GB2055264A GB8023024A GB8023024A GB2055264A GB 2055264 A GB2055264 A GB 2055264A GB 8023024 A GB8023024 A GB 8023024A GB 8023024 A GB8023024 A GB 8023024A GB 2055264 A GB2055264 A GB 2055264A
- Authority
- GB
- United Kingdom
- Prior art keywords
- tripping device
- thermal
- current
- protection switch
- circuit protection
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000010438 heat treatment Methods 0.000 claims abstract description 20
- 239000000956 alloy Substances 0.000 claims 1
- 229910045601 alloy Inorganic materials 0.000 claims 1
- 230000009471 action Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 230000006978 adaptation Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- UGKDIUIOSMUOAW-UHFFFAOYSA-N iron nickel Chemical compound [Fe].[Ni] UGKDIUIOSMUOAW-UHFFFAOYSA-N 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 229910001285 shape-memory alloy Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
- H02H3/085—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current making use of a thermal sensor, e.g. thermistor, heated by the excess current
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H71/00—Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
- H01H71/10—Operating or release mechanisms
- H01H71/12—Automatic release mechanisms with or without manual release
- H01H71/40—Combined electrothermal and electromagnetic mechanisms
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H71/00—Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
- H01H71/74—Means for adjusting the conditions under which the device will function to provide protection
- H01H2071/749—Means for adjusting the conditions under which the device will function to provide protection with a shunt element connected in parallel to magnetic or thermal trip elements, e.g. for adjusting trip current
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Breakers (AREA)
- Thermally Actuated Switches (AREA)
Abstract
The invention relates to an overcurrent protection switch having a thermal tripping device 18 such as a bimetallic strip and a magnetic tripping device 20 comprising a coil which surrounds at least part of a plunger armature. A resistance wire which has a positive temperature coefficient is used as a heating filament for heating the thermal tripping device 18. An additional resistor 22 having a positive temperature coefficient is connected in parallel with the series combination of the tripping devices 18, 20 to achieve shunting. Normally, current is shunted through the resistor 22, but as the temperature rises in the case of a over-current, the resistance of the resistor 22 increases so that the majority of the current is commutated to the combination of the tripping devices 18 and 20. In the case where the current is sufficiently high, the magnetic tripping device 20 opens the contact 16. <IMAGE>
Description
SPECIFICATION
A circuit protection switch
The invention relates to a circuit protection switch with two tripping devices, the functioning of one of the tripping devices being dependent on the heating effect of the current (thermal tripping device) and that of the other tripping device being dependent on the action of the current in a magnetic coil. Both tripping devices open a latch of a contact.
To protect wiring and other devices traversed by the current from over-current, in the case of circuit-breakers or also circuit protection switches, the over-current protection function is effected by a thermal tripping device in the overload range and by an electromagnetic tripping device in the short circuit range. Bimetallic members are generally used as thermal tripping devices, whereas flap or plunger type tripping devices are used as magetic tripping devices. Generally speaking, the individual tripping devices and, in particular, the thermal tripping devices and the coil of the magnetic tripping device are connected in series. Solutions are also known in which the coil and portions of the current paths are connected in parallel to increase the rated current of the thermal tripping device.Moreover, it is known to replace the bimetallic member used for the overload trip by resistance materials having a positive temperature coefficient in which a nickeliron wire is connected in parallel with the magnetic tripping coil.
Circuit breakers are needed for a broad rated current range. A rated current range of from 0.2 to 100 A is normal. The plurality of rated currents necessitates many variations in production, so attempts are being made to reduce the production costs by developing a single basic pattern for a predetermined basic rated current and by permitting adaptation to the other rated currents by means of shunt elements. In parallel with the tripping elements there is connected a shunt by means of which the tripping elements can be designed for small rated currents. Higher rated currents are achieved by means of the shunt or differing shunts (cf. German Offenlegungsschrift
No. 21 01 456). Installation equipment and circuit-breakers can be designed for low rated currents and can be produced on a large scale.
However, a problem arises since, in designs with which the adaptation to predetermined rated currents is effected by shunting, a higher power dissopation has to be taken into consideration than in previously adapted designs.
An object of the invention is to propose a circuit arrangement in which the problem existing in the prior art is avoided, i.e. in which a so-called "adjustment" of the current for the magnetic tripping device relative to the rated currents is avoided. In other words, a circuit protection switch is to be provided in which, on the one hand, the internal resistance is relatively low but in which a high response sensitivity is achieved.
According to the present invention there is provided a circuit protection switch comprising a thermal tripping device connected in series with a magnetic tripping device, each of the tripping devices acting separately on a latch to open a contact, wherein a resistance wire having a positive temperature coefficient is used as heating filament for heating the thermal tripping device, and at least one additional resistor having a positive temperature coefficient is connected in parallel with the series combination of the thermal and magnetic tripping devices to achieve shunting.
The advantages achieved with this arrangement lie essentially in the reduction in the circuit-breaker resistance and in the reduction in the power dissipation. The reduction in the internal resistance, in particular, is very important for control systems due to the low voltage drop needed. Moreover, the reduction in the power dissipation is also important as excessive heating in the instrument and, additionally, in the distribution occurs with excessive power dissipation and this would lead, in turn, to increased expense for achieving adequate cooling and air circulation.
Furthermore, an additional advantage lies in the fact that economic production is permitted due to large numbers of a basic design and that adaption to the desired rated currents is permitted onty by subsequent shunting, i.e. by suitable installation of the correspondingly designed PTC-resistor connected in parallel.
An embodiment of the invention will be illustrated and described in more detail with reference to the drawings.
Figure 1 shows a circuit arrangement for a circuit protection switch according to the invention.
Figure 2 shows a schematic illustration of the important elements of a circuit protection switch.
Figure 1 shows the main current path with two terminals 12 and 14 leading outwards. A contact 16, a thermal tripping device 1 8 and a magnetic tripping device 20 are located in the main current path. A resistor 22 having a positive temperature coefficient is connected in parallel with the thermal tripping device 18 and the magnetic tripping device 20. The thermal tripping device 18 which is designed as a bimetallic member has a heating filament wound round it which is also designed as a resistor having a positive temperature coefficient. This is clarified in Figure 1 by the PTC-resistor 24.
Figure 2 shows a schematic structural embodiment of the arrangement according to
Figure 1. The terminal 12 and the main current guide circuit 10 as well as the thermal tripping device 1 8 can be seen. Also shown is the magnetic tripping device 20 which opens the contact 16 by means of a plunger armature 26 which is shown schematically in broken lines, which contact is formed by a pivoting layer 28 which is rotatable about an axis 30.
A movable contact member 32 is located at the free end of the pivoting lever 28 whereas a fixed contact member 34 is mounted on a wire which is connected to the terminal 14 and corresponds to the main wire 10. A thermal bimetallic member 37 is fixed, with interposition of an insulating member 36, on the main wire 10 which is connected to the terminal 12 and is shown as a Lshaped rail in this case. A heating filament which is designated with the reference numberal 24 to show its identity and which is designed as a PTCresistance wire and is produced from a nickel-iron alloy is wound round the thermal bimetallic member. The thermal tripping device 18 acts via the line of action 38 on a schematically illustrated latch 40 which charges the movable contact lever 28 in the opening direction via another line of action 42 which is illustrated in broken lines.The plunger armature 26 whose right end strikes the movable contact lever directly and whose lefthand end acts via a line of action 44 on the latch 40 is surrounded by a coil 48 which, at one end, is connected via an intermediate wire 46 to the heating element 24 and at its other end via a stranded wire 50 to the movable contact lever 28.
The flow of current travels in the connected state, i.e. when the contact 16 is closed and the two contact members 32 and 34 touch each other, as follows: from the terminal 12 via the wire 10, the heating filament 24, the intermediate wire 46 to the coil 48 and thence via the stranded wire 50 to the contact 1 6 and via the wire 10 to the starting terminal 14.
The PTC-resistor 22 is connected in parallel with the current circuit just described and merges between the terminal 12 and the connecting point 25 of the heating filament 24 at 52 and at the output of the coil 48 at 54 back into the main current path.
In the normal case, i.e. when the contact is closed, the majority of the current flows via the parallel circuit that is to say via the readily conducting PTC-resistor 22. If the current is sufficiently high, the electromagnetic tripping device 20 opens the contacts 16 without the PTCresistor 22 having to change as the resistors in the tripping circuit 20 are dimensioned such that the current flowing through the heating elements 24 and the coil 48 is still sufficiently high. If the heating element 24 were produced from normal material, the current flowing via it would be even smaller as the resistance of a heating element made of normal material is higher.
If there is merely an overcurrent, the PTCresistor 22 becomes hot and increases its resistance so that the majority of the current is commutated to the heating and coil circuit. The heating filament 24 thus heats up and bends the thermal bimetallic member outwards. As the temperature of the thermal bimetallic member is proportional to the i2x R, thus proportional to the square of the traversing current times resistance value, the temperature increases more than in the case of a normal heating filament while the resistance remains almost constant so that the thermal bimetallic member heats up more quickly and is thus bent out more quickly.
The basic pattern of the electric circuit protection switch is thus the part comprising the thermal and the magnetic tripping device. The subsequent shunting and the associated adaptation of this basic pattern to differing rated currents is effected by the PTC-resistor 22 connected in parallel. The main circuit with the thermal and the magnetic tripping device can thus be designed at relatively low rated currents and this basic pattern can be adapted to the correct and necessary rated current by suitable dimensioning of the PTC-resistor 22 or of an additional shunt resistor without further ado.
The above description states that the thermal tripping device is a bimetallic member. It is obviously also possible to use other materials in which a change in shape is produced by heating.
For example, elements of a so-called shape memory alloy can be used which changes its shape at an elevated temperature and thus triggers a latch in virtually the same way as a bimettalic member.
Owing to the PTC-resistor 22 which is connected in parallel, it is possible to design the main circuit with a thermal and magnetic tripping device to relatively low rated currents and it can be adapted to the correct and necessary rated current without further ado by suitable dimensioning of the PTC-resistor 22 or of an additional shunt resistor.
Claims (5)
1. A circuit protection switch comprising a thermal tripping device connected in series with a magnetic tripping device, each of the tripping devices acting separately on a latch to open a contact, wherein a resistance wire having a positive temperature coefficient is used as a heating filament for heating the thermal tripping device, and at least one additional resistor having a positive temperature coefficient is connected in parallel with the series combination of the thermal and magnetic tripping devices to achieve shunting.
2. A circuit protection switch as claimed in claim 1 wherein said thermal tripping device comprises a bimetallic strip.
3. A circuit protection switch as claimed in claim 1 wherein said thermal tripping device comprises a shaped alloy which changes its shape at an elevated temperature whereby to trigger said latch.
4. A circuit protection switch as claimed in any preceding claim wherein said thermal tripping device comprises a plunger armature which is at least partially surrounded by a coil.
5. A circuit protection switch substantially as hereinbefore described with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19792928786 DE2928786A1 (en) | 1979-07-17 | 1979-07-17 | CIRCUIT BREAKER |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2055264A true GB2055264A (en) | 1981-02-25 |
| GB2055264B GB2055264B (en) | 1982-11-10 |
Family
ID=6075916
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8023024A Expired GB2055264B (en) | 1979-07-17 | 1980-07-15 | Circuit protection switch |
Country Status (4)
| Country | Link |
|---|---|
| DE (1) | DE2928786A1 (en) |
| FR (1) | FR2462016A1 (en) |
| GB (1) | GB2055264B (en) |
| IT (1) | IT1131568B (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0614207A2 (en) * | 1993-02-27 | 1994-09-07 | ABBPATENT GmbH | Switching device with a thermal and a magnetic trip device |
| EP0655760A2 (en) * | 1993-11-30 | 1995-05-31 | ABBPATENT GmbH | Electrical switch device |
| WO1997010637A1 (en) * | 1995-09-14 | 1997-03-20 | Raychem Corporation | Overcurrent protection circuit |
| FR2772524A1 (en) * | 1997-12-12 | 1999-06-18 | Legrand Sa | OVERCURRENT PROTECTION DEVICE, ESPECIALLY FOR THE RESET PROTECTION OF A CONTROLLED SWITCH |
| EP1361637A2 (en) * | 1995-09-14 | 2003-11-12 | Tyco Electronics Corporation | Overcurrent protection circuit |
| US9414534B2 (en) | 2012-06-05 | 2016-08-09 | Industrial Technology Research Institute | EMI shielding device and manufacturing method thereof |
| CN109216125A (en) * | 2017-07-06 | 2019-01-15 | 王静洋 | A kind of high breaking circuit breaker without arc |
| US10818462B2 (en) | 2016-03-22 | 2020-10-27 | Eaton Intelligent Power Limited | Circuit breaker |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
| US5737160A (en) * | 1995-09-14 | 1998-04-07 | Raychem Corporation | Electrical switches comprising arrangement of mechanical switches and PCT device |
| CN106898528B (en) * | 2015-12-21 | 2019-09-06 | 浙江正泰电器股份有限公司 | The Pyromagnetic release of breaker |
-
1979
- 1979-07-17 DE DE19792928786 patent/DE2928786A1/en not_active Ceased
-
1980
- 1980-07-14 IT IT23430/80A patent/IT1131568B/en active
- 1980-07-15 GB GB8023024A patent/GB2055264B/en not_active Expired
- 1980-07-16 FR FR8015670A patent/FR2462016A1/en active Granted
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0614207A3 (en) * | 1993-02-27 | 1995-07-26 | Abb Patent Gmbh | Switching device with a thermal and a magnetic trip device. |
| EP0614207A2 (en) * | 1993-02-27 | 1994-09-07 | ABBPATENT GmbH | Switching device with a thermal and a magnetic trip device |
| EP0655760A3 (en) * | 1993-11-30 | 1997-06-04 | Abb Patent Gmbh | Electrical switch device. |
| EP0655760A2 (en) * | 1993-11-30 | 1995-05-31 | ABBPATENT GmbH | Electrical switch device |
| EP1361637A2 (en) * | 1995-09-14 | 2003-11-12 | Tyco Electronics Corporation | Overcurrent protection circuit |
| US5689395A (en) * | 1995-09-14 | 1997-11-18 | Raychem Corporation | Overcurrent protection circuit |
| WO1997010637A1 (en) * | 1995-09-14 | 1997-03-20 | Raychem Corporation | Overcurrent protection circuit |
| EP1361637A3 (en) * | 1995-09-14 | 2004-11-10 | Tyco Electronics Corporation | Overcurrent protection circuit |
| FR2772524A1 (en) * | 1997-12-12 | 1999-06-18 | Legrand Sa | OVERCURRENT PROTECTION DEVICE, ESPECIALLY FOR THE RESET PROTECTION OF A CONTROLLED SWITCH |
| WO1999031778A1 (en) * | 1997-12-12 | 1999-06-24 | Legrand | Protective device against excessive currents, in particular for resettable protection of a controlled switch |
| US6342994B1 (en) | 1997-12-12 | 2002-01-29 | Legrand | Protective device against excessive currents, in particular for resettable protection of a controlled switch |
| US9414534B2 (en) | 2012-06-05 | 2016-08-09 | Industrial Technology Research Institute | EMI shielding device and manufacturing method thereof |
| US10818462B2 (en) | 2016-03-22 | 2020-10-27 | Eaton Intelligent Power Limited | Circuit breaker |
| CN109216125A (en) * | 2017-07-06 | 2019-01-15 | 王静洋 | A kind of high breaking circuit breaker without arc |
| CN109216125B (en) * | 2017-07-06 | 2023-07-25 | 王静洋 | High breaking arcless circuit breaker |
Also Published As
| Publication number | Publication date |
|---|---|
| IT8023430A0 (en) | 1980-07-14 |
| DE2928786A1 (en) | 1981-02-05 |
| IT1131568B (en) | 1986-06-25 |
| GB2055264B (en) | 1982-11-10 |
| FR2462016A1 (en) | 1981-02-06 |
| FR2462016B3 (en) | 1982-05-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |