6. There are approximately 5,000
miles high-voltage transmission lines England and Wales, running
mostly through the countryside.
supply
energy
source
FIGURE 6. long transmission lines the losses can high, but raising
the operating voltage and therefore reducing the current for given power,
the I2
R losses are reduced, the cable diameter reduced and the overall
Circuit
control
Switch
Load
Earthed metal-
work load
Neutral
conductor
Protective
conductor
Line
conductor
Circuit
Protection
Fuse or
MCB
a.
For those who consider transmission towers unsightly, the obvious sugges-
tion might run all cables underground.
Man-made structures erected rural areas often give rise concern, but
every effort made route the overhead lines away from areas where
they might spoil fine view. The cost running the largest lines
underground about million per mile compared with about £200,000
overhead. Farmers
are paid small fee for having transmission line towers their land. This network cables, mostly very high
voltage, suspended from transmission towers, linking together the 175
power stations and millions consumers.c.
We will looking detail all the different wiring systems and circuits
later this book Chapter 14.
.3. d. Over
the years many different tower designs and colours have been tried, but for
the conditions the United Kingdom, galvanized steel lattice towers are
considered the least conspicuous and most efficient.c. areas exceptional beauty
this done, but underground cables are about times more expensive
than the equivalent overhead lines.
Electricity supplies
Electricity generated modern power stations 25kV and fed through
transformers the consumer over complex network cables known as
the national grid system. cable
with terminating gland and seal shown Fig. There full consultation with local author-
ities and interested parties the route which lines will take.5
Component parts electric circuit.Basic electrical circuits and cables
129
for hazardous high-temperature installations such oil refineries,
chemical works, boiler houses and petrol pump installations
