. One
terminal used for each protective
conductor, minimum size 1.Basic Electrical Installation Work
330
or distortions the mains supply and many computers incorporate filters
which produce high protective conductor currents around 3mA. These distor-
tions the mains supply can cause computers ‘crash’ provoke errors
and are shown Fig. supply. clean earth can also taken from this
point, which usually one core the cable and not the armour SWA
cable, and distributed around the final wiring circuit.
C R
R100Ω
C0.45.
FIGURE 14.7.
Clean supplies
Supplies computer circuits must ‘clean’ and ‘secure’.43
Recommended method connecting equipment socket outlets. Mainframe com-
puters and computer networks are sensitive mains distortion interfer-
ence, which referred ‘noise’.45
A simple noise suppressor. Noise mostly caused switching an
inductive circuit which causes transient spike, brush gear making
contact with the commutator segments electric motor.c.
This can provided taking the ring radial circuits for the computer
supplies from point close possible the intake position the
electrical supply the building. Alternatively, the
computer supply can cleaned means filter such that shown in
Fig.1 μF
FIGURE 14.1 and deals with the earthing requirements for the installation of
equipment having high protective conductor currents. This
is clearly not fault current, but typical the current which flows the
CPC equipment under normal operating conditions.43. IEE Guidance Note
7 recommends that equipment should connected double sockets
as shown Fig. 14.
Secure supplies
The mains electrical supply the United Kingdom extremely reliable
and secure.5mm2
Separate
connections
Distribution
fuse board
PE
Ring final circuit supplying
twin socket outlets
(total protective conductor
current exceeding 10mA).c. 14. However, the loss supply mainframe computer com-
puter network for even second can cause the system ‘crash’, and hours
or even days work can lost.
To avoid this, ‘clean’ supply required for the computer network.
Clean supply
Spikes, caused over voltage
transient surging through the mains
‘Noise’: unwanted electrical signals picked
up power lines supply cords
FIGURE 14. 14. IEE Regulation
543.44. mains supply. UPS essentially battery
supply electronically modified provide clean and secure a.
One solution this problem protect ‘precious’ software systems
with uninterruptible power supply (UPS).
Double socket outlets must have two
terminals for protective conductors.44
Distortions the a
