GB1576995A - Installation inporating a fire-damp-proof and/or explosion-proof coupling - Google Patents

Installation inporating a fire-damp-proof and/or explosion-proof coupling Download PDF

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Publication number
GB1576995A
GB1576995A GB6492/78A GB649278A GB1576995A GB 1576995 A GB1576995 A GB 1576995A GB 6492/78 A GB6492/78 A GB 6492/78A GB 649278 A GB649278 A GB 649278A GB 1576995 A GB1576995 A GB 1576995A
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United Kingdom
Prior art keywords
bushing
pressure
transmitters
resistant
receivers
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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.)
Expired
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GB6492/78A
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Siemens AG
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Siemens AG
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Publication date
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Publication of GB1576995A publication Critical patent/GB1576995A/en
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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
    • H02H9/008—Intrinsically safe circuits
    • 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
    • H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage

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  • Arrangements For Transmission Of Measured Signals (AREA)
  • Optical Couplings Of Light Guides (AREA)
  • Photo Coupler, Interrupter, Optical-To-Optical Conversion Devices (AREA)

Description

(54) AN INSTALLATION INCORPORATING A FIRE-DAMP-PROOF AND/OR EXPLOSION-PROOF COUPLING (71) We, SIEMENS AKTIENGESELLSCHAFT, a German company of Berlin and Munich, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to an installation incorporating a fire-damp-proof and/or explosion-proof coupling.
"Fire-damp" is an explosive mixture of methane (CH4) and air formed, for example, in coal mines.
According to the present invention, there is provided an installation incorporating an intrinsically safe electrical circuit and a nonintrinsically safe electrical circuit separated from each other by a pressure-resistant wall, wherein the circuits are coupled together by a fire-damp-proof and/or explosion-proof coupling comprising: a) two or more transmitters for transmitting radiation when acted upon by electrical signals; b) two or more receivers for supplying electrical signals when acted upon by radiation from the transmitters; and c) two or more optical fibres for conducting radiation from the trarismitters to the receivers; at least one of the transmitters and/or at least one of the receivers and/or at least a portion of at least one of the optical fibres being embedded in a pressure-resistant bushing which extends through the wall in pressure-resistant manner.
According to one embodiment of the invention, the coupling comprises: (i) a first transmitter for transmitting radiation when acted upon by an electrical signal from the non-intrinsically safe circuit; (ii) a first receiver for supplying an electrical signal to the intrinsically safe circuit when acted upon by radiation from the first transmitter; (iii) a first optical fibre for conducting radiation from the first transmitter to the first receiver; (iv) a second transmitter for transmitting radiation when acted upon by an electrical signal from the intrinsically safe circuit; (v) a second receiver for supplying an electrical signal to the non-intrinsically safe circuit when acted upon by radiation from the second transmitter; and (vi) a second optical fibre for conducting radiation from the second transmitter to the second receiver.
Conveniently the first transmitter and the second receiver or the first receiver and the second transmitter are embedded in the pressure-resistant bushing.
Preferably each transmitter, each receiver and each optical fibre are housed in pressure-resistant manner.
In order that the present invention may be more fully understood, several embodiments of an installation according to the present invention will now be described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a diagrammatic representation of the basic principle of a known optoelectronic coupling; Figure-2 is a diagrammatic representation of a first embodiment; Figure 3 is a section through a second embodiment; Figure 4 is a section through a third embodiment; and Figure 5 is a section through a detail of the first embodiment.
For the coupling of intrinsically safe and non-intrinsically safe circuits in fire-dampproof or explosion-proof installations, coupling members are known, which each comprises a line bushing, a magnetically operable circuit element including a coil, e.g. a relay, embedded in the bushing and a rectifier connected to the coil. Each bushing is provided with intrinsically safe connecting terminals disposed at one end of the bushing and nonintrinsically safe connections are guided out of the other end of the bushing. The nonintrinsically safe end of the bushing is provided with a screwthread and can be screwed into a bore in a wall of a pressure-resistant housing, which bore is provided with a corresponding screwthread (see German Patent Specifications Nos. 1,180,030 and 1,440,158).Coupling members of this type are predominantly used for transmitting binary signals from the intrinsically safe side to the non-intrinsically safe side of the members or vice versa.
In Figure 1 the basic principle of a known optoelectronic coupling is illustrated diagrammatically. It is to be assumed that a signal is to be transmitted from a non-intrinsically safe circuit, for instance a circuit forming part of an apparatus encased in a pressureresistant manner, which apparatus is at risk from explosion or the presence of fire-damp, connected to the coupling via connections 2.
The connections 1 are connected to a light transmitter 4 which preferably consists of a luminescent diode. The light produced by the light transmitter when acted upon by an electrical signal via the connections 1 is transmitted by means of a light conductive (or optical) fibre 3 to a light receiver 6 which preferably consists of a photo-cell, for example a photo-conductive cell, a photo-diode, a photo-transistor or a photo-thyristor. An electronic switching circuit 7, e.g. an electronic amplifier, may be required at the output of the light receiver 6, depending on the further processing or evaluating of the output signal supplied via the connections 2.
Thus electrical signals may be transmitted from the non-intrinsically safe circuit to the intrinsically safe circuit by converting these signals into light signals and then converting the light signals back to electrical signals without it being necessary to take further protective measures. The immunity to ageing effects and the low attenuation of commercial light conductive fibres allow low-power separation of adequate dielectric strength.
The coupling illustrated diagrammatically in Figure 2 forms part of an installation according to the present invention and differs from the one illustrated in Figure 1 in that a plurality of light conductive fibres 5 are provided, these fibres 5 being guided through a pressure-resistant wall via a pressure-resistant bushing 8 which consists of a socket 9 and two plugs 10 for coupling the light conductive fibre portions on either side of the wall to the portions of the fibres embedded in the socket 9. A section through one of the plugs 10 and the socket 9 is shown in Figure 5. Furthermore the coupling comprises two transmitting and receiving parts 11 and 12 respectively connected to nonintrinsically safe and intrinsically safe circuits via the connections 1, 2.The transmitting and receiving part 11 comprises a light transmitter 4 and a light receiver 6 and possibly an associated switching circuit 7 and is disposed, by way of example, in a housing of protection type (Sch) d (encased in a pressure resistant manner). The transmitting and receiving part 12 comprises similar elements and is disposed, by way of example, in a chamber of protection type (Sch) i (intrinsically safe). The pressure resistant bushing 8 extends through the wall in pressureresistant manner between a chamber of protection type (Sch) e (increased safety) and a chamber of protection type (Sch) d.
The symbols (Sch) d, Sch e and (Sch) i are abbreviations for types of protection set up by the VDE (Association of German Electrical Engineers) in the regulations of fire-damp- and explosion-proofing. (Sch) d indicates that devices which can trigger an explosion of ignitable mixtures are enclosed in a housing which prevents the explosion from being transferred to gas mixtures outside the housing. (Sch) e means that suitable measures are taken which prevent the formation of sparks, electric arcs and raised temperatures at parts, e.g. connection terminals, where in operation these phenomena are not expected. (Sch) i means that the voltage and current which flows in the circuits is so low that the danger of triggering a fire or of igniting explosive gas mixtures or of impermissible heating is obviated.
In the coupling of Figure 2, the transmitting and receiving parts 11, 12 are equipped for the transmission of two signals, that is a signal from the non-intrinsically safe circuit to the intrinsically safe circuit and a signal from the intrinsically safe circuit to the nonintrinsically safe circuit. Thus it is possible to transmit signals in both directions by means of a single coupling. It is of course, also possible to equip the transmitting and receiving part 11 with a plurality of light transmitters and/or receivers including any complementary electronic circuits which might be required, and the transmitting and receiving part 12 with a corresponding number of receivers and/or transmitters with complementary circuits.
Figure 3 shows a coupling in the form of a pressure-resistant bushing 13 in which transmitters and receivers are embedded together with light conductive fibres 16, the bushing 13 being provided with a sleeve 14.
In this embodiment, luminescent diodes 15 are used as the transmitters and phototransistors 17 are used as the receivers.
Reference numeral 18 denotes the complementary circuits which might be necessary. One end of the bushing 13 is provided with a screwthread 20 for screwing the bushing into the pressure-resistant wall 23 of a fire-damp-proof or explosion-proof housing so as to extend therethrough in pressureresistant manner. Terminals 22 and/or sockets for the insertion of suitably constructed plugs 21 may be provided on the bushing 13 for the connection of the signal lines.
Figure 4 shows a coupling which comprises two pressure-resistant bushings 19 and The pressure-resistant bushing 19 contains only one transmitting and receiving part 11, e.g. consisting of two luminescent diodes 15, one photo-transistor 17 and one complementary circuit 18. The pressure-resistant bushing 19 also contains only one transmitting and receiving part 12, e.g. consisting of one luminescent diode 15, two photo-transistors 17 and two complementary circuits 18. The associated light conductive fibres 25 extend between these two bushings 19 and 24 and are combined in a single light cable 26 in which the fibres are encased in plastics material or embedded in a sealing compound.
The bushing 19 is screwed, by way of example, into the pressure-resistant wall 23 of a fire-damp-proof and explosion-proof housing. The light cable 26 ends on the right hand side of the figure in a plug 27 which plugs into a suitably constructed socket 28 on the bushing 24 and thereby establishes optical connection between the bushing 19 and the bushing 24. A similar plug and socket arrangement could be provided for connecting fibres to the bushing 19. The bushing 24 may be replaced by a flat module. The major portion of each optical fibre is disposed outside the bushings 19, 24.
Although, for the sake of clarity, the transmitting and receiving parts 11 and 12 are only represented with two transmitters and one receiver or one transmitter and two receivers (as the case may be), both parts may be provided with a larger number of transmitters and receivers associated with one another in pairs. The number of transmitters and receivers provided is restricted solely by the dimensions of the bushings 19 and 24.
The bushings 13, 19 and 24 may, for example, be made predominantly of steel or light metal (aluminium), and the pressureresistant wall 23 is preferably made of the same material. The bushing 8 is preferably constituted by plastics material or moulding resin. The optical fibres are preferably glass fibres.
The embodiments described above with reference to Figures 2 to 5 of the drawing enable electrical signals to be transmitted from an installation part which is at risk from explosion or the presence of fire-damp to at least one other installation part or vice versa in a manner such as to ensure separation of intrinsically safe and non-intrinsically safe circuits.
Transmission of electrical signals converted into light signals via light conductive fibres means that a galvanic separation of the circuits is achieved with the result that an electrical connection of high currents in the non-intrinsically safe circuit to the intrinsically safe circuit is obviated. Thus an explosion on the non-intrinsically safe side, i.e. in the fire-damp-proof housing, does not have an effect on the intrinsically safe side.
The space requirement for these couplings is small, even if a plurality of transmitters and receivers is needed for transmitting control, measurement, or alarm signals in one or both directions.
WHAT WE CLAIM IS: 1. An installation incorporating an intrinsically safe electrical circuit and a nonintrinsically safe electrical circuit separated from each other by a pressure-resistant wall, wherein the circuits are coupled together by a fire-damp-proof and/or explosion-proof coupling comprising: a) two or more transmitters for transmitting radiation when acted upon by electrical signals; b) two or more receivers for supplying electrical signals when acted upon by radiation from the transmitters; and c) two or more optical fibres for conducting radiation from the transmitters to the receivers; at least one of the transmitters and/or at least one of the receivers and/or at least a portion of at least one of the optical fibres being embedded in a pressure-resistant bushing which extends through the wall in pressure-resistant manner.
2. An installation according to claim 1, wherein the coupling comprises: (i) a first transmitter for transmitting radiation when acted upon by an electrical signal from the non-intrinsically safe circuit; (ii) a first receiver for supplying an electrical signal to the intrinsically safe circuit when acted upon by radiation from the first transmitter; (iii) a first optical fibre for conducting radiation from the first transmitter to the first receiver; (iv) a second transmitter for transmitting radiation when acted upon by an electrical signal from the intrinsically safe circuit; (v) a second receiver for supplying an electrical signal to the non-intrinsically safe
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (14)

**WARNING** start of CLMS field may overlap end of DESC **. transmitters and receivers are embedded together with light conductive fibres 16, the bushing 13 being provided with a sleeve 14. In this embodiment, luminescent diodes 15 are used as the transmitters and phototransistors 17 are used as the receivers. Reference numeral 18 denotes the complementary circuits which might be necessary. One end of the bushing 13 is provided with a screwthread 20 for screwing the bushing into the pressure-resistant wall 23 of a fire-damp-proof or explosion-proof housing so as to extend therethrough in pressureresistant manner. Terminals 22 and/or sockets for the insertion of suitably constructed plugs 21 may be provided on the bushing 13 for the connection of the signal lines. Figure 4 shows a coupling which comprises two pressure-resistant bushings 19 and The pressure-resistant bushing 19 contains only one transmitting and receiving part 11, e.g. consisting of two luminescent diodes 15, one photo-transistor 17 and one complementary circuit 18. The pressure-resistant bushing 19 also contains only one transmitting and receiving part 12, e.g. consisting of one luminescent diode 15, two photo-transistors 17 and two complementary circuits 18. The associated light conductive fibres 25 extend between these two bushings 19 and 24 and are combined in a single light cable 26 in which the fibres are encased in plastics material or embedded in a sealing compound. The bushing 19 is screwed, by way of example, into the pressure-resistant wall 23 of a fire-damp-proof and explosion-proof housing. The light cable 26 ends on the right hand side of the figure in a plug 27 which plugs into a suitably constructed socket 28 on the bushing 24 and thereby establishes optical connection between the bushing 19 and the bushing 24. A similar plug and socket arrangement could be provided for connecting fibres to the bushing 19. The bushing 24 may be replaced by a flat module. The major portion of each optical fibre is disposed outside the bushings 19, 24. Although, for the sake of clarity, the transmitting and receiving parts 11 and 12 are only represented with two transmitters and one receiver or one transmitter and two receivers (as the case may be), both parts may be provided with a larger number of transmitters and receivers associated with one another in pairs. The number of transmitters and receivers provided is restricted solely by the dimensions of the bushings 19 and 24. The bushings 13, 19 and 24 may, for example, be made predominantly of steel or light metal (aluminium), and the pressureresistant wall 23 is preferably made of the same material. The bushing 8 is preferably constituted by plastics material or moulding resin. The optical fibres are preferably glass fibres. The embodiments described above with reference to Figures 2 to 5 of the drawing enable electrical signals to be transmitted from an installation part which is at risk from explosion or the presence of fire-damp to at least one other installation part or vice versa in a manner such as to ensure separation of intrinsically safe and non-intrinsically safe circuits. Transmission of electrical signals converted into light signals via light conductive fibres means that a galvanic separation of the circuits is achieved with the result that an electrical connection of high currents in the non-intrinsically safe circuit to the intrinsically safe circuit is obviated. Thus an explosion on the non-intrinsically safe side, i.e. in the fire-damp-proof housing, does not have an effect on the intrinsically safe side. The space requirement for these couplings is small, even if a plurality of transmitters and receivers is needed for transmitting control, measurement, or alarm signals in one or both directions. WHAT WE CLAIM IS:
1. An installation incorporating an intrinsically safe electrical circuit and a nonintrinsically safe electrical circuit separated from each other by a pressure-resistant wall, wherein the circuits are coupled together by a fire-damp-proof and/or explosion-proof coupling comprising: a) two or more transmitters for transmitting radiation when acted upon by electrical signals; b) two or more receivers for supplying electrical signals when acted upon by radiation from the transmitters; and c) two or more optical fibres for conducting radiation from the transmitters to the receivers; at least one of the transmitters and/or at least one of the receivers and/or at least a portion of at least one of the optical fibres being embedded in a pressure-resistant bushing which extends through the wall in pressure-resistant manner.
2. An installation according to claim 1, wherein the coupling comprises: (i) a first transmitter for transmitting radiation when acted upon by an electrical signal from the non-intrinsically safe circuit; (ii) a first receiver for supplying an electrical signal to the intrinsically safe circuit when acted upon by radiation from the first transmitter; (iii) a first optical fibre for conducting radiation from the first transmitter to the first receiver; (iv) a second transmitter for transmitting radiation when acted upon by an electrical signal from the intrinsically safe circuit; (v) a second receiver for supplying an electrical signal to the non-intrinsically safe
circuit when acted upon by radiation from the second transmitter; and (vi) a second optical fibre for conducting radiation from the second transmitter to the second receiver.
3. An installation according to claim 1 or 2, wherein a portion of each of the optical fibres is embedded in the pressure-resistant bushing.
4. An installation according to claim 3, wherein the portions of the optical fibres embedded in the bushings are coupled to further portions of the optical fibres on each side of the pressure-resistant wall by a respective plug and socket arrangement.
5. An installation according to claim 1 or 2, wherein the transmitters, the receivers and the optical fibres are all embedded in the pressure-resistant bushing.
6. An installation according to claim 1 or 2, wherein at least one, but not all, the transmitters and at least one, but not all, the receivers are embedded in the pressureresistant bushing.
7. An installation according to claim 6 when appended to claim 2, wherein the first transmitter and the second receiver or the first receiver and the second transmitter are embedded in the pressure-resistant bushing.
8. An installation according to claim 6 or 7, wherein the major portion of each optical fibre is disposed outside the pressureresistant bushing.
9. An installation according to claim 6, 7 or 8, wherein the optical fibres are connected to the pressure-resistant bushing by a plug and socket arrangement.
10. An installation according to any preceding claim, wherein the pressure-resistant bushing is screwed into the pressure-resistant wall.
11. An installation according to any preceding claim except claim 3 or 4 or any other claim when appended directly or indirectly to claim 3 or 4, wherein the bushing is provided with one or more sockets and/or one or more terminals electrically connected to the transmitters and receivers.
12. An installation according to any preceding claim, wherein each transmitter comprises a luminescent diode and each receiver comprises a photo-conductive cell, a photodiode a photo-transistor or a photothyristor.
13. An installation according to claim 12, wherein each receiver further comprises an amplifier.
14. An installation incorporating an intrinsically safe electrical circuit and a nonintrinsically safe electrical circuit separated from each other by a pressure-resistant wall wherein the circuits are coupled together by a fire-damp-proof and/or explosion-proof coupling substantially as hereinbefore described with reference to, and as illustrated in, Figures 2 and 5 or Figure 3 Figure 4ofthe accompanying drawing.
GB6492/78A 1977-02-18 1978-02-20 Installation inporating a fire-damp-proof and/or explosion-proof coupling Expired GB1576995A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2707190A DE2707190B2 (en) 1977-02-18 1977-02-18 Arrangement for optoelectronic coupling of intrinsically safe and non-intrinsically safe circuits, especially in firedamp or explosion-proof systems

Publications (1)

Publication Number Publication Date
GB1576995A true GB1576995A (en) 1980-10-15

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GB6492/78A Expired GB1576995A (en) 1977-02-18 1978-02-20 Installation inporating a fire-damp-proof and/or explosion-proof coupling

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JP (1) JPS53102686A (en)
DE (1) DE2707190B2 (en)
GB (1) GB1576995A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2203859A (en) * 1987-04-21 1988-10-26 Preformed Line Products Co Resin encapsulating fiber optic cable where it passes through housing wall
GB2250871A (en) * 1990-12-12 1992-06-17 British Gas Plc Data transmission system

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2913262C2 (en) * 1979-04-03 1982-04-29 Kabelwerke Reinshagen Gmbh, 5600 Wuppertal Electro-optical connector
JPS5615088A (en) * 1979-07-19 1981-02-13 Omron Tateisi Electronics Co Optical fiber type photoelectric switch
DE3109888C2 (en) * 1981-03-14 1983-07-21 Kabelwerke Reinshagen Gmbh, 5600 Wuppertal Opto-electrical transmission path
JPS57174069U (en) * 1981-04-27 1982-11-02
US4556927A (en) * 1983-04-14 1985-12-03 Gilbarco, Inc. Intrinsically safe signal coupler
FR2560726B1 (en) * 1984-03-05 1986-11-21 Nal Etu Telecommunication Cent PROTECTION DEVICE AGAINST ELECTRICAL DISTURBANCES BETWEEN A TERMINAL AND A TELEPHONE LINE
DE3642923A1 (en) * 1986-12-16 1988-06-23 Siemens Ag Circuit arrangement for telecommunications switching systems, in particular videophone switching systems, with the setting-up of broadband links
US4954923A (en) * 1988-08-19 1990-09-04 Cooper Industries, Inc. Intrinsic safety module interface
US5144157A (en) * 1991-09-23 1992-09-01 Raytheon Company Pin diode driver circuit for radar system
DE4233108A1 (en) * 1992-10-02 1994-04-07 Fernsprech Und Signalbau Gmbh Safety coupling device, esp. for explosive environments - contains device with intrinsically safe components connected via cable and plug connector to device with encapsulated components

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DD115812A1 (en) * 1974-11-18 1975-10-12

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2203859A (en) * 1987-04-21 1988-10-26 Preformed Line Products Co Resin encapsulating fiber optic cable where it passes through housing wall
GB2203859B (en) * 1987-04-21 1991-06-12 Preformed Line Products Co Encapsulated fiber optic closure and method of encapsulating same
GB2250871A (en) * 1990-12-12 1992-06-17 British Gas Plc Data transmission system
AU630041B2 (en) * 1990-12-12 1992-10-15 British Gas Plc Data transmission system
GB2250871B (en) * 1990-12-12 1994-07-20 British Gas Plc Data transmission system
US5333088A (en) * 1990-12-12 1994-07-26 British Gas Plc Data transmission system

Also Published As

Publication number Publication date
DE2707190B2 (en) 1979-05-17
DE2707190A1 (en) 1978-08-24
JPS53102686A (en) 1978-09-07

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