Installation procedures
2-9
2.i.12
Earthing
2.1.12.1
Functional earth
The functional earth is separated from the Power Protective earth in the
CCV. The functional earth for the 2+8 must be derived from the main
building earth point and not from any 13A ring main. Current BT
practices for functional earthing should be applied on all installations.
The 2+8 requires a functional earth to be connected if:
•
The functional earth terminal is to be used for
Electro-static Precautions
(ESP).
See paragraph 1.1.6.
•
It is to be piggy-backed on a PABX requiring a forward Earth recall from
the 2+8 to the host PABX.
•
The 2+8 could be subjected to high-voltage line surges. This a
discretionary decision of the system maintainer and should be agreed
before acceptance testing.
The functional earth wire must be 1.5mm2 solid copper conductor using
cream-coloured insulation. Any other colours such as green or
green/yellow must not be used because these are reserved for the power
protective earths.
Feed the functional earth wire into the CCU and terminate securely on
the functional earth terminal (see Figure 2.4) provided on the CCU PCB.
CAUTION
Do not use excessive force when tightening this screw.
2.1.12.2
Mains protective earth
The mains protective earth is derived from the mains supply socket.
Before connecting the CCU power plug, test that a good earth exists at
the mains socket earth with an Earth Loop Impedance Tester (Tester
400A or equivalent).
You should also ensure that there is a good continuity between the earth
pin of the mains plug and the metalwork of the CCU base.
2.i.13
Setting the CCU OIL switches
Refer to the customer 2+8 configuration form.
There are four banks of 8-way Dual In Line (DIL) switches on the main
Printed circuit board (see Figure 2.4). These must now be set for the
required operating conditions (see Figure 2.5). Check each switch in
each switch bank and ensure that it is correctly set before switching on
the mains supply.
If a switch setting is changed while the mains power is connected, it will
be necessary to switch off the CCU and switch it back on again for the
processor to reset itself and store the new switch setting.
TPU
1371Issue3(4/91)
Summary of Contents for 2+8
Page 1: ...Installation and maintenance manual 2 8...
Page 2: ......
Page 36: ...Notes 10 2 Notes 10 3 TPU 1371Issue3 4 91...
Page 37: ...Notes TPU 1371Issue3 4 91 10 4...
