transmissiion lines

1. TRANSMISSION LINE
• What is it?
• Uses?
• Practical Application?
*Coaxial cable *Microstrip *Stripline
*Balanced lines *Twisted pair *Star quad
*Over-Head Trasnmission Line
*Cables

2. OVER HEAD POWER LINES
 What are they?
 What are they used for?
 Materials?
 Use?
 Operating Voltages?

3. CLASSIFICATION OF OHTL
 Low Voltage <1000 volts
 Medium Voltage(Distribution) b/w 1kv-33kv
 High Voltage(subtransmission) <100 kv
*Use?
• Extra High Voltage Transmission >230 kv
-800 kv
• Ultra High Voltage Transmission >800 kv

6. CONDUCTOR
A conductor is a material that facilitates
the flow of electricity (or electric current)
through a transmission line.
• Copper
• Steel
• Aluminium
• ACSR

7. COPPER
• Abundantly available.
• Excellent conductor.
• Exist in three forms.
i. Soft drawn
ii. Medium drawn
iii.Hard drawn

8. COPPER
 Soft-drawn copper conductors are commonly used in
short transmission line spans and to ground
electrical systems. They are flexible and resistant to
breaking even under high stress.
 Medium-drawn copper conductors are used for
medium-range distribution lines.
 Hard-drawn copper conductors are used in longer
spans (greater than 200 feet) and are the strongest of
the three. Their strength, however, makes them
inflexible and often difficult to work with.

9. STEEL
• Not much effective.
• Rusts.(Due to which steel conductors are hardly used
alone)
• Steel conductors are commonly galvanized.
(coated with a layer of zinc to counteract their
rusting tendency)
• Three to five times stronger than copper.
conductors, and can be used for longer spans
with fewer supports.

10. ALUMINIUM
• Higher thermal expansion..
• Lower strength.
• Less than half the conductivity of copper..
• Light weight.(less sag)
• Cheap.
Aluminum conductors are commonly used for
higher-voltage overhead transmission lines,
power cables, busbars, motors, heating elements,
heat sinks and foil windings.

11. ACSR CONDUCTOR
• Steel-Reinforced Aluminium
• Used in medium-, high- and extra-high-voltage (EHV)
transmission lines.
• High-strength
• High-capacity
• Exhibit excellent conductivity
• Light weight(used in overhead transmission lines,
river crossings and longer spans)

12.  ACSR transmission lines have a central steel strand,
surrounded by outer aluminium strands.
 The steel conductor supports the weight of the
transmission line while the aluminium is used for its
conductive properties
ACSR transmission cables are available in specific sizes
and varying amounts of central steel strands as well
as outer aluminium conductors

13. TYPES OF OHTL W.R.T
CONSTRUCTION
Bundle conductors
Ground wires
Insulated conductors
Circuits

14. BUNDLE CONDUCTORS

15. GROUND WIRES

16. INSULATED CONDUCTORS

17. CIRCUITS

18. FURTHER APPLICATIONS
Used to supply
transmitting antennas
For Train power