GB2388970A

GB2388970A - Connector for use in hazardous environment

Info

Publication number: GB2388970A
Application number: GB0308870A
Authority: GB
Inventors: Edward Hand
Original assignee: Hawke Cable Glands Ltd
Current assignee: Hawke Cable Glands Ltd
Priority date: 2002-04-19
Filing date: 2003-04-17
Publication date: 2003-11-26
Also published as: GB0308870D0; AU2003227874A1; GB0208954D0; WO2003090320A1

Abstract

An electrical connector 10 suitable for use in classified hazardous areas and hazardous environments comprising a first part 12 and a second part 18 operable to mate to form an electrical connection. Each part has electrical contact means, 26 and 28, disposed therein, and enclosing means 30 operable to prevent a flame front or spark travelling from the electrical contact means to a potentially flammable atmosphere external to the connector, and also to prevent contamination of the electrical contact means by fluids normally disposed external to the connector. Spring biassed elements 34 and 32 are moved by fixed elements 42 and 40 during mating.

Description

An electrical connector.

5 The present invention relates to electrical connectors, particularly to electrical connectors suitable for use in classified hazardous areas and hazardous environments.

Hazardous areas are environments in which potentially flammable atmospheres exist. The flammable substance is usually a gas or vapour, but may also be dust or fibre. Hazardous lo areas generally exist in industries such as, for example, coal mining, petrochemical plants, chemical plants, offshore oil platforms, sewage treatment, paint shops, dry cleaning, petrol stations and grain handling industries.

In relation to gases, The international Electrotechnical Commission (lEC) and the 5 European Committee for Electrotechnical Standardisation (CENELEC) have classified hazardous areas into zones relating to the likelihood of the hazard actually being present in the immediate environment. The classified zones include: Zone 0, which represents an area in which an explosive atmosphere is constantly present, or is present for long periods of time; 20 Zone I, which represents and area in which an explosive atmosphere is likely to occur periodically in normal operation; and, Zone 2, which represents an area in which an explosive atmosphere is not likely to occur in normal operation and if it does it will exist for a short period only.

Is Certification also exists for electrical devices intended for use in the various hazardous area zones. These include: Flameproof (Ex d), wherein safety is achieved by the suppression of flame propagation to prevent any explosion within the switch enclosure igniting the surrounding atmosphere; 30 Increased Safety (Ex e), wherein safely is achieved by ensuring the device is non sparking in normal operation and under certain fault conditions;

Flameproof/lncreased Safety (Ex ed), wherein safety is achieved by combing the protective concepts of the above mentioned Ex d and Ex e. Additionally, Ex ed devices should have no external flame paths; and, I!ltrinsic Safety (Ex ia), wherein safety is achieved by maintaining electrical 5 energy below the minimum ignition energy of the hazard.

Electrical connectors having Ex d, Ex e or Ex ed certification, are operable in Zones 1 and 2, whereas only devices certified as Ex ia are operable in Zone 0.

0 Electrical connectors generally take the form of a male part and a female part adapted to mate to form an electrical connection. The path that a spark or flame front is likely to take from the electrical contacts of an electrical connector to the flammable atmosphere surrounding the connector, is commonly known as the flame path.

5 Known connectors generally comply with the requirements of Ex ed certification by Conning each part thereof from an insulating material having both thermal and electrical insulating properties suitable to prevent a flame front or a spark, respectively, crossing the flame path from the electrical contacts to the potentially flammable atmosphere.

20 However, disconnection ofthese connectors exposes the contacts to the flammable atmosphere in which a spark is likely to cause an explosion. Furthermore, if an explosion occurs within the connector causing an external surface thereof to rise above the ignition temperature of the surrounding flammable atmosphere, an explosion may result.

25 Therefore, electrical charge must be removed from the connectors during mating and demating thereof. This is often a hazardous activity, inconvenient, and results in relatively high installation and maintenance costs.

Furthermore, in electrical connector applications in which the connector is submersed in 30 water such as, for example, sub-marine cabling, connectors conducting a charge cannot be demated while submersed, as the electrical contacts will be exposed to the liquid.

Again, this is often a hazardous activity, inconvenient and results in relatively high installation and maintenance costs.

In both hazardous and submersible cabling applications there are often numerous s electrical connectors in close proximity. When disconnecting such electrical connectors, for example, during maintenance, significant care is needed to ensure that each male part of each electrical connector is reconnected to the correct corresponding female part. This increases the time taken to carry out installation, testing and maintenance and therefore increases the relative costs associated with such activities. Furthermore' it is often lo necessary to isolate cables from electrical charge for relatively short periods of time in instances such as, for example, when testing other cables. It is therefore desirable for a connector to be electrically disconnected whilst still maintaining a mechanical connection between its constituent parts.

5 It is an object of the present invention to provide an electrical connector suitable for use in a flammable atmosphere, which may be safely mated and demated without removing the electrical charge therefrom.

It is also an object of the present invention to provide an electrical connector suitable for 20 use in liquid, which may be mated and demated without exposing its electrical contacts to the liquid in which it is submersed.

Furthermore, it is also an object of the present invention to provide an electrical connector suitable for use in the above mentioned applications, which may be electrically 2s isolated whilst maintaining mechanical connection between its constituent parts.

According to the present invention an electrical connector suitable for use in a flammable atmosphere comprises a first part and a second part adapted to mate to form an electrical connection, each part comprising electrical contact means and enclosing means operable 30 to maintain enclosure of the electrical contact means within that part following demating thereof, to at least substantially maintain insulation across at least the minimum allowable

flame path between the contact and the atmosphere thereby preventing escape from the connector of means significant to ignite the flammable atmosphere.

The means significant to ignite the flammable atmosphere may be at least one of a spark 5 or a flame front.

The maintained insulation may be at least one of electrical insulation and thermal insulation. lo The enclosing means may comprise sealing means operable to at least substantially prevent exposure of the electrical contact means to fluids disposed externally of the electrical connector.

Alternatively, or additionally, the sealing means may be operable to at least substantially 5 prevent exposure of the electrical contact means to dust disposed externally of the electrical connector.

According to a second aspect of the present invention an electrical connector suitable for use in a liquid comprises a first and second part adapted to mate to form an electrical 20 connection, each part comprising electrical contact means and enclosing means, the enclosing means having sealing means adapted, following demating of the parts, to maintain a boundary which is at least substantially impermeable to the liquid in which the connector is disposed.

25 The enclosing means may also be operable to maintain enclosure of the electrical contact means within the respective parts during at least one of mating and demating thereof.

The enclosing means may comprise a first displaceable member, disposed on the first part of the connector, and a second displaceable member disposed on the second part of the 30 connector Each displaceable member is preferably adapted to be displaceable between a first position, in which each is disposed to overlie their respective electrical contact

means, and a second position, in which each is disposed to expose their respective electrical contact means.

The enclosing means may also comprise a first fixed member, disposed on the first part i s and operable to displace the second displaceable member between the first and second positions thereof, and a second fixed member, operable to displace the first displaceable member between the first and second positions thereof.

The electrical contact means may be suitably disposed on the first and second fixed lo members, such that mating of the first and second parts causes the first fixed member to displace the second displaceable member and the second fixed member to displace the first displaceable member, such that one fixed member at least partially overlies the other fixed member, thereby aligning the electrical contacts to fomm an electrical connection.

5 The first fixed member is advantageously disposed within and substantially shares a longitudinal axis with the first displaceable member to form a first coaxial member having a fixed inner member and a displaceable outer member. Similarly, the second displaceable member is advantageously disposed within and substantially shares a longitudinal axis with the second fixed member to form a second coaxial member having 20 a displaceable inner member and a fixed outer member.

Advantageously, on mating of the first and second parts, the first and second coaxial members substantially share a longitudinal axis. More advantageously, the fixed inner member, disposed on the first coaxial member, is operable to displace the displaceable 25 inner member, disposed on the second coaxial members and the fixed outer member, disposed on the second coaxial member, is operable to displace the displaceable outer member, disposed on the first coaxial member, thereby aligning the electrical contact means to form an electrical connection.

30 Preferably, the first fixed member and the second displaceable member are substantially cylindrical in shape, each having an external radius defining one or more outer surfaces.

More preferably, the external radius of the fixed member is substantially equal to the external radius of the second displaceable member.

5 Preferably, the first displaceable member and the second fixed member are substantially annular in shape, each having internal and external radii.

More preferably, the internal radius of the first displaceable member is substantially equal to the internal radius of the second fixed member.

The enclosing means may also comprise biasing means, which may be operable to bias at least one of the first and second displaceable members into the first position, in which each overlies their respective electrical contact means. The biasing means may be disposed in the first and second parts of the connector and may comprise at least one 5 spring.

The electrical connector preferably comprises retaining means operable to retain the first and second parts in a mated mode. More preferably, the electrical connector may advantageously comprise retaining means operable to retain the first and second parts in a 20 first mode of connection, wherein the first and second parts are mechanically connected and electrically disconnected, or in a second mode of connection, wherein the first and second parts are mechanically connected and electrically connected.

The retaining means comprises at least one region of greater radius, disposed on one of 2s the first or second parts, and at least one region of lesser radius disposed on the opposing part, wherein, in use, the regions of greater and lesser radius are engageable with each other to retain the first and second parts in the first or second mode of connection.

( 7 The, or each, region of greater radius may comprise a pin, disposed on the first or second part to extend radially outwards therefrom.

Preferably, the electrical connector also comprises axis alignment means operable to s align the longitudinal axis of the first and second parts at least during interconnection thereof. Additionally, or alternatively, the alignment means may also be operable to align the electrical contact means disposed on the first part with the electrical contact means disposed on the second part.

lo The axis alignment means may comprise an alignment member disposed on one ofthe first or second parts and an alignment member receiver disposed on the opposing part.

Preferably the alignment receiver is shaped to correspond with the shape of the alignment member. 5 The connector may comprise electrical contact alignment means comprising an alignment pin disposed on the first or second part and a pin receiver disposed on the opposing part. The pin and receiver may be disposed on each part so as to operably combine with the axis alignment means to at least substantially prevent rotational displacement of one part relative to the opposing part.

The electrical connector may be of a single pole type or, alternatively, may be of a multi pole type.

The electrical connector may be used to form part of a network, and may be used to 25 connect instrumentation in field bus applications.

The present invention will be described further, by way of example, with reference to the accompanying drawings, in which: 30 Figure I is a cross section of an electrical connector according to the present invention, in a mated mode;

Figure 2 is a cross section of a first part of the electrical connector of Figure 1, in a demated mode; 5 Figure 3 is a cross section of a second part of the electrical connector of Figures I and 2, in demated mode; Figure 4 is a cross section of the first part of Figure 2, but with a first displaceable member displaced to reveal electrical contact means; Figure 5 is a cross section of the second part of Figure 3, but with a second displaceable member displaced to reveal electrical contact means; Figure 6 is a schematic drawing of a container which forms part of means for retaining 5 the electrical connector in a connected mode; Figure 7 is a schematic drawing of a bezel which, in combination with the container of Figure 6, forms the retaining means; 20 Figure 8 is a cross section of an electrical connector, according to the present invention, in a mechanical and electrical disconnected mode, having retaining means of Figures 6 and 7; Figure i) is a cross section of the electrical connector of Figure 8 in a mechanically 25 connected and electrically disconnected mode of connection; and, Figure 10 is a cross section of the electrical connector of Figure 8 in a mechanically connected and electrically connected mode of connection.

! 9 Referring to Figures I to S. there is shown an electrical connector 10 which, when combined with suitable outer housings, is suitable for use in a flammable atmosphere, comprising a first part 12, having a proximate end 14 and a distal end 16, and a second part 18, having a proximate end 20 and a distal end 22, operable to mate, via the s proximate ends, to form an electrical connection.

The first part 12 is disposed in a housing 24.

Each of the first and second parts, 12 and 18 respectively, have electrical contact means, lo 26 and 28, respectively, and enclosing means 30.

The enclosing means 30 comprises a first displaceable member 32, disposed on the first part 12, and a second displaceable member 34, disposed on the second part 18, each displaceable member adapted to be displaceable between a first position 36 (as shown in 5 Figures 2 and 3), in which each is disposed to overlie their respective electrical contact means, 26 and 28, and a second position 38 (as shown in Iigures 4 and 5), in which each is disposed to reveal their respective electrical contact means, 26 and 28.

The enclosing means 30 also comprises a first fixed member 40, disposed on the first part 20 12, and a second fixed member 42, disposed on the second part 18.

The second fixed member 42 is also operable as a housing for the second part 18.

The first fixed member 40 and the second displaceable member 34 are cylindrical in 25 shape, each having a longitudinal axis, 44a and 44a', respectively, and each having an external radius, 46 and 48, respectively. The external radii, 46 and 48, are equal and define external surfaces, 50 and 52, of the first fixed member 40 and the second displaceable member 34, respectively.

30 The first displaceable member 32 and the second fixed member 42 are annular in shape, each having a longitudinal axis, 44b and 44b' respectively, and each having an internal

( lo radius, 54 and 56 respectively. The internal radii 54 and 56 are equal and define internal surfaces 58 and 60 of the first displaceable member 32 and the second fixed member 42, respectively. 5 The external radius 46 of the first fixed member 40 is less than the internal radius 54 of the first displaceable member 32 and is disposed within the first displaceable member so as to share the longitudinal axis 44 thereby forming a first coaxial member 62 having a fixed inner member 40' and a displaceable outer member 32'. The displaceable outer member 32' slides over the fixed inner member 40', in the direction of the longitudinal lo axis, between the first position 36, shown in Figure 2, and the second position 38, shown in Figure 4.

Similarly, but conversely, the external radius 48 of the second displaceable member 34 is less than the internal radius 56 of the second fixed member 42 and is disposed within the 5 second fixed member so as to share the longitudinal axis 44 thereby forming a second coaxial member 64 having a displaceable inner member 34' and a fixed outer member 42'. The displaceable inner member 34'slides within the fixed outer member 42', in the direction of the longitudinal axis, between the first position 36, shown in Figure 3, and the second position 38, shown in Figure 5.

The first and second parts,l2 and 18, each have biasing means 66 and 68, respectively.

The first biasing means 66 has an annular biasing base 70 mounted on the fixed inner member 40' so as to share the longitudinal axis 44 therewith. The annular biasing base 70 25 is fixed, relative to the fixed inner member 40', in the region of the distal end 16 of the first part 12.

The biasing means also comprises a spring 72, which is attached at one end to the biasing base 70 and extends outwardly therefrom, in the direction of the longitudinal axis 44, 30 towards the proximate end 14 where it is attached to the displaceable outer member 32'.

Similarly, but conversely, the second biasing means 68 has a cylindrical biasing base 74 attached, in the region of the distal end 22 of the second part 18, to the fixed outer member 42' so as to share the longitudinal axis 44 therewith. The biasing base 74 is fixed in position relative to the fixed outer member 42'.

The biasing means 68 also comprises a spring 76, which is attached to the biasing base 74 and extends outwardly therefrom, in the direction of the longitudinal axis 44, towards the proximate end 20 where it is attached to the displaceable inner member 34'.

0 The biasing means, 66 and 68, are operable to bias the displaceable outer member 32'and the displaceable inner member 34' into the first position 36.

Each of the first and second biasing means, 66 and 68, also have stop means, 78 and 80, respectively. The stop means are operable to prevent the displaceable members, 32 and 5 34, being biased beyond the proximate ends of each of the first and second parts.

The first stop means 78 comprises a region of greater radius disposed adjacent a peripheral region of the displaceable outer member 32', to form a shoulder 82 therein, and a region of lesser radius disposed on a peripheral region of the housing 24, to form an 20 abutment member 84 therein, adjacent the proximate end 14 of the first part 12.

In use, in a demated mode, the displaceable outer member 32' is prevented from being biased beyond the proximate end 14 by abutment of the shoulder 82 against the abutment member 84, as shown in Figure 2.

Is Similarly, the second stop means 80 comprises a region of greater radius disposed adjacent a peripheral region of the displaceable inner member 34', to form a shoulder 86 therein, and a region of lesser radius disposed on a peripheral region of the fixed outer member 42' to form an abutment member 88 therein, adjacent the proximate end 20 of the second part 18.

( 12 In use, in a demated mode, the displaceable inner member 34' is prevented from being biased beyond the proximate end 20 of the second part 18, by abutment of the shoulder 86 against the abutment member 88, as shown in Figure 4.

5 The first electrical contact means 26 comprises a set of three electrical contacts 90. Each contact having a contact end 92 and a connecting end 94. The fixed inner member 40' comprises a set of three spaced apart channels 96 formed in the external surface 50 thereof, in the direction of the longitudinal axis 44. In each of the channels, one of the electrical contacts 90 is disposed. Each channel 96 has sufficient depth to house each lo respective contact 90 without protrusion thereof beyond the external surface SO of the inner fixed member 40'. Each contact 92 is fixed relative to the inner fixed member 40'at the annular biasing base 70 leaving the contact end 92 free of attachment and the connecting end 94 to extend to the region of the distal end 16.

I 5 The inner fixed member 40' also comprises a spring 98, disposed in each channel 96 to underlie the contact end 92, and operable to bias the contact end 92 into a position in which it protrudes beyond the external surface 50, as shown in Figure 4.

The displaceable outer member 32' comprises three contact abutments 100, each 20 disposed to extend into a respective channel 96 to abut the respective electrical contact 90. When the displaceable outer member 32' is disposed in the first position 36, that is, when it is biased to overlie each contact end 92 as shown in Figure 2, the contact abutments 25 l DO overcome the resilience of the respective spring 98 to retain the contact end 94 within the depth of their respective channel 96. This creates enclosures 102, defined by part of the respective channel 96 and internal surfaces of the displaceable outer member 32', in which the contact ends 92 are enclosed.

30 The second electrical contact means 28 comprises a set ofthree contact plates 104. Each contact plates is disposed on the internal surface 60 of the fixed outer member 42' to

( 13 extend from a region adjacent the proximate end 20 to a region of the distal end 22, as shown in Figures 3 and 5.

The electrical connector l O also comprises axis alignment means 106 operable to align 5 the longitudinal axis 44 of the first part 12 with that of the second part 18. The alignment means 106 comprises an alignment member 108 disposed on the fixed inner member 40' to share the longitudinal axis 44 therewith and extend beyond the proximate end l 4 thereof, and an alignment member receiver 110, disposed in the proximate end 20 of the displaceable inner member 34' to share the longitudinal axis therewith. The member 108 lo and the receiver l 10 have equal diameters such that, on mating of the first and second parts, the member fits tightly within the receiver thereby aligning the longitudinal axis of the first and second parts.

The electrical connector also comprises electrical contact alignment means 112, operable 5 to align the electrical contacts 90 with the electrical contact plates 104 during mating of the first and second parts, and to prevent rotational displacement of one part relative to the opposing part when in the mated mode. The electrical contact alignment means 112 comprises an alignment pin 114 disposed on the fixed inner member 40' to extend outwardly from the proximate end 14 thereof, and a pin receiver 116 disposed on the 20 proximate end 20 of the displaceable inner member 34'.

The pin 1 14 and the pin receiver 116 are disposed in corresponding positions, spaced away from the longitudinal axis 44, suitable to align the electrical contacts of the first part with the electrical contacts of the second part during mating thereof and to prevent 25 rotational displacement of the first and second parts when in the mated mode.

The electrical connector also comprises sealing means 1 18, operable to prevent exposure of the electrical contact means, 26 and 28, to fluid disposed in the environment external to the connector.

The sealing means may comprise, disposed on the first part 12, a first seal 120 disposed on the f xed inner member 40, to provide a seal between the external surface 50 thereof and the displaceable outer member 32', and a second seal 122, disposed on an inner surface of the housing 24 to provide a seal between there and the displaceable outer 5 member 32'.

Disposed on the second part 14, the sealing means comprises a third seal 124, disposed on the fixed outer member 42' to provide a seal between an inner surface thereof and an outer surface of the displaceable inner member 34'.

In use, from the demated mode, the axis alignment member 108 is aligned with alignment member receiver 1 10 and the alignment pin 1 14 aligned with the pin receiver 1 16. The proximate end 14, of the first part 12, is abutted to the proximate end 20 of the second part 1 8.

Further force applied in the mating direction overcomes the opposing biasing forces, provided by the biasing means 66 and 68, whereby the fixed inner member 40' displaces the displaceable inner member 34'and, simultaneously, the fixed outer member 42' displaces the displaceable outer member 32', thereby aligning the contact ends 92 ofthe 20 first part 12 with the contact plates 104 of the second part 18 to form an electrical connection between the two parts.

During mating of the first and second parts, as described above, the electrical contact means 26 and 28 are continuously enclosed by an arrangement of members suitable to 25 suppress the flame path of a spark or flame front, when in the demated mode, during mating of the first and second parts and in the mated mode. Therefore, on mating of the first and second parts, the flamepath is in place before the corresponding contacts have moved sufficiently close to each other for there to be a possibility of arcing or sparking therebetween, particularly, for example, in the context of Exe certification. On demating 30 of the first and second parts the flamepath is maintained until at least the point when arcing or sparking can no longer occur.

In an alternative embodiment ofthe invention, the electrical connector 10 is suitable for use submersed in waters wherein the first and second parts, 12 and 18, form a waterproof barrier between the water and the electrical contact means, 26 and 28.

In this second embodiment, sealing means of a superior quality are needed to operate under greater pressures which may be caused by the depth of the water in which the connector is operating.

0 The arrangement of the members as described above in relation to the first embodiment, in combination with superior sealing means, is operable to maintain isolation of the electrical contact means, 26 and 28, relative to the water external to the electrical connector 10, when in the demated mode, during mating of the first and second parts, and when in the mated mode.

Referring to Figures 6 to 10, there is shown retaining means 200 comprising a container i.

202 (Figure 6) operable to contain the second part 18 and to cooperate with a bezel 204 (Figure 7) disposed around the first part 12, to retain the first and second parts in a first mode of connection, wherein the first and second parts are mechanically connected and 20 electrically disconnected, or a second mode of connection, wherein the first and second parts are mechanically and electrically connected. However, it will be appreciated that alternatively the container may contain the first part and the bezel may be disposed around the second part.

2s Referring to Figure 6 the container 202 is cylindrical in shape and comprises an engaging end 206 and an outer surface 208. The outer surface has two regions of greater radius in the form of a first pair of diametrically opposing retaining pins 210 and two further regions of greater radius in the fore, of a second pair of diametrically opposing retaining pins 21 2(only one of the pair shown). The first pair ofretaining pins 210 are angularly so spaced apart relative to the second pair 212 such that each retaining pin has a 90 relationship with its adjacent pins. However, it should be noted that the retaining pins

( 16 may alternatively be disposed such that they have an angular relationship other than 90 relative to each other. The first pair of retaining pins 210 are also longitudinally spaced apart relative to the second pair of retaining pins 212. The container also comprises an abutment collar 214.

s Referring to Figure 7 the bezel 204 is also cylindrical in shape and is radially dimensioned internally such that when engaging the container 202 its internal surface 216 is able to travel over the pairs of pins, 210 and 212, disposed on the container 202.

lo The bezel 204 comprises two regions of reduced radius, relative to the internal surface 216 thereof, which form a pair of diametrically opposing retaining stops 220 disposed around the internal circumference of the bezel 204. The pair of retaining stops 220 comprise an inner abutment face 222 and an outer abutment face 224 and are circumferentially separated by a pair of diametrically opposed gaps 226 dimensioned to 5 receive the first and second pairs of pins, 210 and 212, therethrough.

Referring also to Figures 9 and 10, the electrical connector 10 is retained in the first or second mode of connection by the biasing force provided by the first and second biasing means, 66 and 68. The biasing force maintains abutment of the inner abutment face 222 20 with the first pair of pins 210 in relation to retention of the connector in the first mode of connection and the second pair of pins 212 in relation to retention of the connector in the second mode of connection.

Referring also to Figure 8, during mating of the first and second parts, 12 and 18, the first 25 pair of pins 210 are aligned with the pair of gaps 226 and, by applying a force sufficient to overcome the opposing biasing force, the engaging end 206 of the container is inserted into the bezel 204 until the first pair of pins 210 have cleared the pair of gaps 226. The bezel 204 is then rotated so that the pair of stops 220 overlie the first pair of pins 210.

The applied force is then released thereby allowing the biasing force to cause abutment of 30 the inner abutment faces 222 with the first pair of pins 210, thereby retaining the electrical connector 10 in the first mode of connection, wherein the first and second parts,

l7 12 and 18, are mechanically connected and electrically disconnected as shown in Figure 9. The first and second parts, 12 and l 8, are converted from the first mode of connection to 5 the second mode of connection by further rotation of the bezel 204 so that the pair of gaps 226 align with the second pair of pins 212. This will be 90 rotation from alignment of the pair of gaps 226 with the first pair of pins 210. Further applied force, sufficient to overcome the biasing force, passes the second pair of pins 212 through the pair of gaps 226. When the second pair of pins 212 have cleared the pair of gaps 226 the bezel is lo again rotated to the extent that the pair of retaining stops 220 overlie the second pair of pins 212. The applied force is then released allowing the biasing force to cause abutment of the inner abutment faces 222 with the second pair of pins 210, thereby forming the second mode of connection, wherein the first and second parts, 12 and 18, are mechanically connected and electrically connected as shown in Figure 10.

The longitudinal spacing between the first pair of pins and the second pair of pins allows mechanical connection of the first part 12 relative to the second part 18 in either an! electrically connected or electrically disconnected mode.

20 It will be appreciated that in order to convert the electrical connector I O from the second mode of connection to the first mode of connection, and to mechanically disconnect the parts, a procedure in reverse to that mentioned above is carried out.

It should be noted that the first and second modes of connection may be utilised in 25 hazardous environments wherein the electrical connector may be certified for use in, for example, an Ex d hazardous area zone in the first mode of connection and an Ex e hazardous area zone in the second mode of connection.

Furthermore, in relation to the above mentioned alternative embodiment wherein the 30 electrical connector 10 is suitable for use submerged in water, the above mentioned retaining means allows electrical disconnection whilst simultaneously maintaining

mechanical connection of the first and second parts, 12 and 18, thereby providing means for enhanced isolation of the electrical contact means 26 and 28, relative to the water external to the electrical connector 10 and ease of location of electrically disconnected first and second parts relating to a corresponding cable connection

Claims

C|a As: 1. An electrical connector suitable for use in a flammable

atmosphere comprising a first 5 part and a second part adapted to mate to form an electrical connection, each part comprising electrical contact means and enclosing means operable to maintain enclosure of the electrical contact means within that part following demating thereof to at least substantially maintain insulation across at least the minimum allowable flame path, between the contact and the atmosphere thereby preventing escape from lo the connector of means significant to ignite the flammable atmosphere.
2. An electrical connector as claimed in Claim 1, wherein the means significant to ignite

the flammable atmosphere comprises at least one of a spark and a flame front.

5
3. An electrical connector as claimed in Claims I and 2, wherein the maintained insulation is at least one of electrical insulation and thermal insulation.
4. An electrical contact as claimed in any of the preceding claims, wherein the enclosing means comprises sealing means operable to at least substantially prevent exposure of 20 the electrical contact means to fluid disposed externally of the electrical connector.
5. An electrical connector as claimed in Claim 4, wherein the sealing means is operable to at least substantially prevent exposure of the electrical contact means to at least one of fluid and dust, disposed externally of the electrical connector.
6. An electrical connector suitable for use in liquid comprising a first and second part adapted to mate to form an electrical connection, each part comprising electrical contact means and enclosing means, the enclosing means having sealing means adapted, following demating of the parts, to maintain a boundary which is at least 30 substantially impermeable to the liquid in which the connector is disposed.

(
7. An electrical connector as claimed in any of the preceding claims wherein the enclosing means is operable to maintain enclosure of the electrical contact means s within the respective parts during at least one of mating and demating thereof.
8. An electrical connector as claimed in any of the preceding claims, wherein the enclosing means comprises a first displaceable member disposed on the first part, and a second displaceable member disposed on the second part, each member adapted to lo be displaceable between a first position, in which each is disposed to overlie their respective electrical contact means, and a second position, in which each is disposed to reveal their respective electrical contact means.
9. An electrical connector as claimed in Claim 8, wherein the enclosing means 5 comprises a first fixed member, disposed on the first part and operable to displace the second displacement member between the first and second positions thereof, and a second fixed member, disposed on the second part, operable to displace the first displaceable member between the first and second positions thereof.

20
10. An electrical connector as claimed in Claims 8 and 9, wherein the electrical contact means are suitably disposed on the first and second fixed members, such that mating of the first and second parts causes the first fixed member to displace the second displaceable member, and the second fixed member to displace the first displaceable member, such that one fixed member at least partially overlies the other fixed 2s member, thereby aligning the electrical contacts to form an electrical connection.
11. An electrical connector as claimed in Claims 8 to 1 O. wherein the first fixed member is disposed within and substantially shares a longitudinal axis with the first displaceable member to form a first coaxial member having a f xed inner member and 30 a displaceable outer member, and the second displaceable member is disposed within and substantially shares a longitudinal axis with the second fixed member to form a

second coaxial member having a displaceable inner member and a fixed outer member.
12. An electrical connector as claimed in Claim 11, wherein, on mating of the first and s second parts, the first and second coaxial members substantially share a longitudinal axis and the fixed inner member, disposed on the first coaxial member, is operable to displace the displaceable inner member, disposed on the second coaxial member, and the fixed outer member, disposed on the second coaxial member, is operable to displace the displaceable outer member, disposed on the first coaxial member, thereby aligning the electrical contact means to form an electrical connection.
13. An electrical connector as claimed in Claims to 12, wherein the first fixed member and the second displaceable member are substantially cylindrical in shape, each having an external radius.
14. An electrical connector as claimed in Claim 13, wherein the external radius of the first fixed member is substantially equal to the external radius of the second displaceable member.

20
15. An electrical connector as claimed in Claims 8 to 14, wherein the first displaceable member and the second fixed member are substantially annular in shape, each having internal and external radii.
16. An electrical connector as claimed in claimed in Claim}S. wherein the internal radius 2s of the first displaceable member is substantially equal to the internal radius of the second fixed member.
17. An electrical connector as claimed in any of the preceding claims, wherein the enclosing means comprises biasing means.
18. An electrical connector as claimed in Claim 17, wherein the biasing means is operable to bias at least one of the first and second displaceable members into the first position, in which each overlies their respective electrical contact.

5
19. An electrical connector as claimed in Claims 17 and 18, wherein the biasing means is disposed in at least one of the first and second parts.
20. An electrical connector as claimed in Claim 17 to 19, wherein the biasing means comprises at least one spring.
21. An electrical connector as claimed in any of the preceding claims, comprising retaining means operable to retain the first and second parts in a first mode of connection, wherein the first and second parts are mechanically connected and electrically disconnected, or in a second mode of connection, wherein the first and I S second parts are mechanically connected and electrically connected.
22. An electrical connector as claimed in Claim 21, wherein the first mode of connection the flamepath is maintained such that the connector conforms with Ex d certification and in the second mode of connection the flamepath is maintained such that the 20 connector conforms to Ex e certification.
23. An electrical connector as claimed in Claims 21 or 22, wherein the retaining means comprises at least one region of greater radius, disposed on one of the first or second parts, and at least one region of lesser radius disposed on the opposing part, wherein, 2s in use, the regions of greater and lesser radius are engageable with each other to retain the first and second parts in the first or second mode of connection.
24. An electrical connector as claimed in any of the preceding claims, comprising axis alignment means operable to align the longitudinal axis of the first and second parts at 30 least during mating thereof.
25. An electrical connector as claimed in Claim 24, wherein the alignment means comprises an alignment member disposed on one of the first or second parts and an alignment member receiver disposed on the opposing part.

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26. An electrical connector as claimed in Claim 25, wherein the alignment member and the alignment receiver are disposed on the longitudinal axis of the first and second parts.
27. An electrical connector as claimed in any of the preceding claims, comprising lo electrical contact alignment means operable to align the electrical contact means of the first part with the electrical contact means of the second part, during mating thereof and maintain alignment thereof when in the mated mode.
28. An electrical connector as claimed in Claim 27, wherein the electrical contact 5 alignment means comprises a pin disposed on one of the first or second parts and a pin receiver disposed on the opposing part.
29. An electrical connector as claimed in Claim 28, wherein the pin and the pin receiver are suitably disposed on the first and second parts to prevent substantial rotational 20 displacement of one of the first or second parts relative to the opposing part, during mating thereof and when in the mated mode.
30. An electrical connector as claimed in any of the preceding claims operable for use in field bus applications.
31. An electrical connector as claimed in any of the preceding claims, wherein the connector is of a single pole type.
32. An electrical connector as claimed in Claims I to 30, wherein the connector is of a so multi pole type.
33. An electrical connector substantially as herein described with reference to, as shown in, the accompanying drawings.

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