GB2237937A - Electric switch for use in hazardous environments - Google Patents

Electric switch for use in hazardous environments Download PDF

Info

Publication number
GB2237937A
GB2237937A GB8925077A GB8925077A GB2237937A GB 2237937 A GB2237937 A GB 2237937A GB 8925077 A GB8925077 A GB 8925077A GB 8925077 A GB8925077 A GB 8925077A GB 2237937 A GB2237937 A GB 2237937A
Authority
GB
United Kingdom
Prior art keywords
housing
electric switch
sealed
solid state
state switching
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.)
Withdrawn
Application number
GB8925077A
Other versions
GB8925077D0 (en
Inventor
Gerwin Williams
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RYAN MINING SERVICES Ltd
Original Assignee
RYAN MINING SERVICES Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by RYAN MINING SERVICES Ltd filed Critical RYAN MINING SERVICES Ltd
Priority to GB8925077A priority Critical patent/GB2237937A/en
Publication of GB8925077D0 publication Critical patent/GB8925077D0/en
Publication of GB2237937A publication Critical patent/GB2237937A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K5/00—Casings, cabinets or drawers for electric apparatus
    • H05K5/06—Hermetically-sealed casings
    • H05K5/064—Hermetically-sealed casings sealed by potting, e.g. waterproof resin poured in a rigid casing

Abstract

An electric switch for use in hazardous or potentially explosive atmospheres comprising a solid state switching circuit 10, embedded in a body 12 of foamed plastics material, which fills an hermetically sealed plastics housing 14. Flameproof cable connectors 18, 20 are sealed to the housing 14 for connection to incoming and outgoing electrical power cables 22, 24, and further cables 26, 28 are sealed to the casing and lead to a start/stop controller and a load respectively. <IMAGE>

Description

ELECTRIC SWITCH FOR HAZARDOUS ENVIRONMENTS This invention relates to an electric switch for use in hazardous environments, particularly in areas liable to explosive atmosphere e.g. underground mines.
At present in underground mines, electrical switching is carried out using flameproof switchgear, which is designed to contain any explosion within its enclosure without allowing any flame or spark to escape which could ignite methane in the atmosphere. An explosion will occur if air and gas are present in certain proportions and if then that mixture receives a spark of sufficient power.
We have now devised an electric switch which is safe to use in hazardous atmospheres because it provides a space which will remain free of gas and also because it eliminates the generation of any spark.
Thus, in accordance with this invention, there is provided an electric switch which comprises a sealed housing, solid state switching means within the housing, and foamed plastics material filling the housing and embedding the solid state switching means.
Because the electrical switching is carried out by solid state circuits, there is no possibility for the generation of any spark. The housing excludes any explosive mixture of air and gas from the interior thereof, but even if the housing develops a leak, the foamed plastics material prevents the air and gas mixture from reaching the switching circuit, thus guarding against any breakdown of the switching circuit which might conceivably lead to a spark.
The switch is preferably provided with flame proof connectors e.g. of known type for connecting electic cables thereto.
An embodiment of this invention will now be described by way of example only and with reference to the accompanying drawing, the single figure of which is a diagrammatic cross section through one form of electric switch in accordance with the invention.
Referring to the drawing, there is shown an electric switch for use in hazardous or potentially explosive atmospheres, e.g. in underground mines. The electric switch comprises a circuit board 10 on which are mounted solid state switching circuits or device. This circuit is embedded in a body 12 of insitu foamed closed-cell plastics material, which fills an hermetically sealed plastics housing 14.
Flameproof cable connectors 18,20 are mounted in sealed manner to the housing for connection to incoming and outgoing 3phase electrical power cables 22,24, the connectors 18,20 being connected to the circuit 10 within the housing. Two further cables 26,28 lead from the circuit 10 and through the housing in sealed manner: cable 26 leads to a remote start/stop controller and cable 28 leads to a load (typically an electric motor) being controlled.
It will be appreciated that the flameproof connectors 18,20 are sealed off from the atmosphere when the power cables 22,24 are coupled to them. Further, the sealed housing 14 prevents any air/gas mixture entering, but even should the housing 14 become cracked or otherwise develop a leak, the body of foamed plastics prevents the mixture reaching the circuit 10.
Because this circuit is composed of solid state switching devices, the switching takes place without risk of generating any spark, but should any breakdown of the circuit occur, there will be no risk of explosion because of the air/gas mixture is excluded.

Claims (3)

1) An electric switch comprising a sealed housing, a solid state switching means within the housing, and foamed plastics material filling the housing and embedding the solid state switching means.
2) An electric switch as claimed in claim 1 in which the switch is provided with flame proof connectors.
3) An electric switch substantially as described herein with reference to the accompanying drawings.
GB8925077A 1989-11-07 1989-11-07 Electric switch for use in hazardous environments Withdrawn GB2237937A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8925077A GB2237937A (en) 1989-11-07 1989-11-07 Electric switch for use in hazardous environments

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8925077A GB2237937A (en) 1989-11-07 1989-11-07 Electric switch for use in hazardous environments

Publications (2)

Publication Number Publication Date
GB8925077D0 GB8925077D0 (en) 1989-12-28
GB2237937A true GB2237937A (en) 1991-05-15

Family

ID=10665844

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8925077A Withdrawn GB2237937A (en) 1989-11-07 1989-11-07 Electric switch for use in hazardous environments

Country Status (1)

Country Link
GB (1) GB2237937A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2839415A1 (en) * 2002-05-02 2003-11-07 Sylea Car electronic assembly having circuit card/component/conductor held within plastic mould.
FR2908011A1 (en) * 2006-10-25 2008-05-02 Valeo Electronique Sys Liaison Electrical or electronic package, especially for use in automobiles, comprises a base and side walls and a board defining a space that is filled with a filler material
WO2008064623A1 (en) * 2006-11-27 2008-06-05 Hilmar Kraus Assembly comprising electric and/or electronic components
FR3030750A1 (en) * 2014-12-22 2016-06-24 Finsecur OPTICAL DETECTOR OF A VALUE OF A PHYSICAL SIZE OF THE ATMOSPHERE REPRESENTATIVE OF A DANGER

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1259804A (en) * 1969-02-28 1972-01-12 Hawker Siddeley Dynamics Ltd Improvements in or relating to the manufacture of electrical circuit assemblies
US3772452A (en) * 1972-04-17 1973-11-13 Globe Union Inc An encapsulated electrical device
GB1469184A (en) * 1973-04-17 1977-03-30 Roederstein Kondensatoren Electronic circuit assembly
GB2102207A (en) * 1981-07-17 1983-01-26 Ferranti Ltd Electrical circuit assembly
GB2146176A (en) * 1983-09-05 1985-04-11 Gec Avionics Encapsulated assemblies of electrical components
GB2212677A (en) * 1987-11-16 1989-07-26 Sanyo Electric Co An electric circuit and a molded electric board for supplying controlled frequency electric power to a load

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1259804A (en) * 1969-02-28 1972-01-12 Hawker Siddeley Dynamics Ltd Improvements in or relating to the manufacture of electrical circuit assemblies
US3772452A (en) * 1972-04-17 1973-11-13 Globe Union Inc An encapsulated electrical device
GB1469184A (en) * 1973-04-17 1977-03-30 Roederstein Kondensatoren Electronic circuit assembly
GB2102207A (en) * 1981-07-17 1983-01-26 Ferranti Ltd Electrical circuit assembly
GB2146176A (en) * 1983-09-05 1985-04-11 Gec Avionics Encapsulated assemblies of electrical components
GB2212677A (en) * 1987-11-16 1989-07-26 Sanyo Electric Co An electric circuit and a molded electric board for supplying controlled frequency electric power to a load

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2839415A1 (en) * 2002-05-02 2003-11-07 Sylea Car electronic assembly having circuit card/component/conductor held within plastic mould.
FR2908011A1 (en) * 2006-10-25 2008-05-02 Valeo Electronique Sys Liaison Electrical or electronic package, especially for use in automobiles, comprises a base and side walls and a board defining a space that is filled with a filler material
WO2008064623A1 (en) * 2006-11-27 2008-06-05 Hilmar Kraus Assembly comprising electric and/or electronic components
FR3030750A1 (en) * 2014-12-22 2016-06-24 Finsecur OPTICAL DETECTOR OF A VALUE OF A PHYSICAL SIZE OF THE ATMOSPHERE REPRESENTATIVE OF A DANGER
WO2016102891A1 (en) * 2014-12-22 2016-06-30 Finsecur Optical detector of a value of an atmospheric physical quantity representative of a danger
US20170370835A1 (en) * 2014-12-22 2017-12-28 Finsecur Optical detector of a value of an atmospheric physical quantity representative of a danger

Also Published As

Publication number Publication date
GB8925077D0 (en) 1989-12-28

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Legal Events

Date Code Title Description
WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)