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4 ELECTRICAL CONNECTIONS
4.1 Connections – General
Warning.
• Mains power – before making any connections, ensure that the power supply, any high voltage-operated control circuits
and high common mode voltages are switched off.
Information.
• Earthing (grounding) – stud terminal(s) is fitted to the transmitter case for bus-bar earth (ground) connection – see Fig. 4.2 or 4.5.
• Cable routing – always route signal output cable leads and mains-carrying/relay cables separately, ideally in earthed metal
conduit. Twist the signal output leads together or use screened cable with the screen connected to the case earth stud.
Ensure that the cables enter the transmitter through the glands nearest the appropriate screw terminals and are short and
direct. Do not tuck excess cable into the terminal compartment.
• Cable glands & conduit fittings – ensure a moisture-tight fit when using cable glands, conduit fittings and blanking plugs/bungs
(M20 holes).
• Relays –the relay contacts are voltage-free and must be appropriately connected in series with the power supply and the
alarm/control device which they are to actuate. Ensure that the contact rating is not exceeded. Refer also to Section 4.1.2
for relay contact protection details when the relays are to be used for switching loads.
• Retransmission output – Do not exceed the maximum load specification for the selected current retransmission range
(see the associated Specification sheet).
Because the retransmission output is isolated the –ve terminal must be connected to earth (ground) if connecting to the
isolated input of another device.
4.1.1 Cable and Gland Specifications
Caution.
• Cabling – connections between the Transmitter and the Interface Electronics Unit must be in accordance with BS5345 pt3
– Installation and Maintenance Requirements for Electrical Apparatus with type 'd' Protection Flameproof Enclosure.
• Glands – EEx d glands used on the Interface Electronics Unit must be of the EEx d 'Barrier Gland' type with BASEEFA
certification because the enclosure is over 2 liters volume, has a source of ignition within and is designed for use in Zone
1 areas (reference BS5345 part 3.
Information.
• The M20 glands ready-fitted to wall-mounted instruments accept cable of between 4 and 7mm diameter.
• A spare set of grommets is supplied for cable sizes between 8 and 12mm diameter.
Gland Specification
M20 BASEEFA certified
EEx d barrier gland
(not supplied)
M20 BASEEFA certified
EEx d barrier gland
(not supplied)
Table 4.1 Cable and Gland Specifications (electrical requirements only)
6
Signal Cable
Mains Power Cable
Cable Specifications
Signal cable
16/0.2, 4-core copper, overall screened,
(not supplied)
flameproof (two pairs)
Max. loop resistance 750Ω
Mains power cable
3-core, 0.5mm
(not supplied)
2
copper (min.)
or
4685
4680
Gland Specification
4680
4685
M20 Uncertified
No gland
(fitted)
required
4680
4685
M20 Uncertified
No gland
(fitted)
required
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