Secure supplies
The mains electrical supply the United Kingdom extremely reliable
and secure. These distor-
tions the mains supply can cause computers ‘crash’ provoke errors
and are shown Fig.7. 14.
Double socket outlets must have two
terminals for protective conductors.
FIGURE 14. 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.44.
. 14.43
Recommended method connecting equipment socket outlets. IEE Regulation
543.
Clean supplies
Supplies computer circuits must ‘clean’ and ‘secure’.
Clean supply
Spikes, caused over voltage
transient surging through the mains
‘Noise’: unwanted electrical signals picked
up power lines supply cords
FIGURE 14.
C R
R100Ω
C0. This
is clearly not fault current, but typical the current which flows the
CPC equipment under normal operating conditions.
To avoid this, ‘clean’ supply required for the computer network. supply.1 μF
FIGURE 14. IEE Guidance Note
7 recommends that equipment should connected double sockets
as shown Fig. 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. Mainframe com-
puters and computer networks are sensitive mains distortion interfer-
ence, which referred ‘noise’. UPS essentially battery
supply electronically modified provide clean and secure a.45
A simple noise suppressor.
One solution this problem protect ‘precious’ software systems
with uninterruptible power supply (UPS).
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. 14. One
terminal used for each protective
conductor, minimum size 1.44
Distortions the a.1 and deals with the earthing requirements for the installation of
equipment having high protective conductor currents.c.43. mains supply.c.Basic Electrical Installation Work
330
or distortions the mains supply and many computers incorporate filters
which produce high protective conductor currents around 3mA. Noise mostly caused switching an
inductive circuit which causes transient spike, brush gear making
contact with the commutator segments electric motor.45.5mm2
Separate
connections
Distribution
fuse board
PE
Ring final circuit supplying
twin socket outlets
(total protective conductor
current exceeding 10mA)
