Plugs and Sockets

At the time of writing (1999) the best available flame retardance is to UL94 VI rating but the incandescent wire resistance of up to 960°C makes the materials of interest in such electrical applications as plug and socket containers. 

Business machinery applications include keys for keyboards, typewriter ribbon guides, plug and socket connectors and optical cable sheathing. 

Busbar trunking systems are frequently employed in machine shops to facilitate relocation of the equipment. The busbars are located overhead, suspended from the roof stmcture, and arranged, in conjunction with the lighting system, in a suitable grid pattern. Fused plugs and sockets provide outlets to individual items of equipment. 

Each item of apparatus tested, all flexible cords, switches, fuses, plugs and socket outlets are in good serviceable condition except as stated. There is no sign of overloading of conductors or accessories except as stated. Apparatus tested includesjdoes not include Portable Appliances. 

Unlike phenol-formaldehyde polymers, the amino resins are not themselves deeply coloured, but are of a naturally light appearance. They can be easily pigmented to give a variety of shades, which leads to application in uses where good appearance is highly valued, for example in decorative tableware, laminated resins for furniture, and modem white electrical plugs and sockets. 

The General requirements cover apparatus grouping and temperature classification, constructional requirements for enclosures and fasteners, connection facilities and terminal compartments, cable entries and supplementary requirements for rotating electrical machines, switchgear, plugs and sockets and luminaires. A third part of the standards cover type verifications and tests as well as marking requirements. 

The main field of application of oil immersion - o is the explosion protection of Group II transformers in the high power range (up to some 1000 kVA). The terminal compartments often comply with increased safety -e or plug and socket connectors (in e ) are used in the high voltage range (see Section 6.7). 

Figure 6.10 shows a typical example for a q-apparatus. It is a power supply for intrinsically safe electric circuits to be installed in zone 1 (and zone 2). The power input (at 24 V AC/DC level) is fed via flameproof plug-and-socket connectors to the apparatus. So, the power supply can be replaced under load without conflicting with the requirements of explosion protection. 

Figure 6.18 Flameproof (EEx dl) plug-and-socket connectors for outgoing power lines (1140 V 3 AC, up to 450A) fitted at the sidewall of an EEx p I switchboard (this is shown in Fig. 6.19).

Plug-and-socket connectors complying with increased safety - e - (see Section 6.7.2) or with flameproof enclosure - d - (see Section 6.8.10) provide a simple installation and maintenance of pressurized apparatus, especially in coal mines where frequent and rapid changes of place are required. Figure 6.18 shows flameproof plug-and-socket connectors fitted at the sidewall of a Group I pressurized switchboard. 

A second example of encapsulation is a contactless operating plug-and-socket system with integrated electronics suitable for zone 1 application (Figs 6.37 and 6.38). The system allows power and data transmission with PROFIBUS DP/VI. The socket with an integrated pigtail cable is attached to a terminal box in increased safety - e Within the socket, the 24 V DC power... 

Figure 6.37 Contactless plug-and-socket system, unidirectional inductive power transmission, bidirectional data transmission via optical fibres.

Figure 6.54 High voltage plug-and-socket connector (single pole)...

Figure 6.81 Flameproof plug-and-socket connectors ( cable couplers ), fitted into a flameproof enclosure (EEx dl equipment for coal mines).

Plug-and-socket connectors, cable couplers, see Fig. 6.81. These parts are inserted into an opening of the flameproof enclosure and act as a flameproof seal. This also applies to the unplugged state of plug and socket. Such means are favoured where apparatus is frequently removed, e.g. in coal mines (Group I application). 

At the low voltage side, plug-and-socket connectors are applied for the outgoing lines. So, no low voltage terminal compartments are fitted. 

Dropdown slide rails for circuit breaker withdrawal 16 SF6 circuit breaker chamber 17 Auxiliary wiring harness multi-pin plug and socket 18 Integral skid underbase 19 Voltage transformer 20 Earth terminal 21 Fuses 22 Split clamp connectors 23 Earth fault current transformer 24 Incoming adaptor and half coupler. 

Requirements are given in EN 50014 as well as in IEC 60079-0 General requirements, covering all types of protection. Plugs and sockets shall be mechanically or electrically (or otherwise) interlocked to avoid disconnection when energized, or shall be fixed together by special fasteners and additionally be marked with a warning label DO NOT SEPARATE WHEN... 

ENERGIZED. (In Germany, plugs and sockets with an interlock are known as Steckvorrichtungen, without an interlock as Steckverbinder. )... 

The standards for flameproof enclosure - d EN 50018 and IEC 60079-1 give additional requirements for plugs and sockets not fixed together by means of special fasteners ... 

An example of a flameproof plug and socket is given in Figs 6.140 and 6.141. The socket - in the non-operating mode - is covered by a rotating shutter ... 

The plug and socket according to Fig. 6.142 shows a coaxial arrangement of the contacts of a three-phase system. The central multi-contact pin is intended for six pilot and auxiliary circuits. Plug and socket are fixed together by means of a special fastener. 

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