Applications of carbon materials in electrical engineering Introduction Carbon Use for Making Filament of Incandescent Lamp Carbon Use for Making Electrical Contacts Carbon Use for Making Resistors Carbon Use for Making Brushes for Electrical DC Machines and Alternators Carbon Use for Making Dry Cell Elements Carbon Electrodes Use for Electric Furnaces Graphite Carbon Use for Arc Lighting and Welding Electrodes Carbon use as Component of Vacuum Valves and Tubes

1. Presented by
Dr. R. RAJA, M.E., Ph.D.,
Associate Professor, Department of EEE,
Muthayammal Engineering College, (Autonomous)
Namakkal (Dt), Rasipuram – 637408
MUTHAYAMMAL ENGINEERING COLLEGE
(An Autonomous Institution)
(Approved by AICTE, New Delhi, Accredited by NAAC, NBA & Affiliated to Anna University),
Rasipuram - 637 408, Namakkal Dist., Tamil Nadu, India.
Applications of Carbon Materials in
Electrical Engineering

2. Introduction
 Carbon, in various forms and in combination of other materials, is widely used
in electrical engineering.
 Electrical carbon materials are manufactured from graphite and other forms of
carbon. Carbon is having following applications in Electrical Engineering
1. For making filament of incandescent lamp
2. For making electrical contacts
3. For making resistors
4. For making brushes for electrical machines such as DC machines, alternators
5. For making battery cell elements
6. For making carbon electrodes for electric furnaces
7. Arc lighting and welding electrodes
8. For making component for vacuum valves and tubes
9. For makings parts for telecommunication equipment.
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3. Carbon Use for Making Filament of Incandescent Lamp
 Carbon is used with inert gas medium for making filament for incandescent
lamp.
 Resistivity of carbon is about 1000-7000 µΩ -cm and melting point is about
3500oC.
 Which make it suitable for making filament for Incandescent lamp. Commercial
efficiency of carbon filament lamp is 4.5 lumens per watts or 3.5 watts per
candle power.
 Carbon is having blackening effect in incandescent lamp.
 To prevent this blackening of bulb, the working temperature is limited up to
1800oC.
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4. Carbon Use for Making Electrical Contacts
 Carbon is used as fiber formed from polymers by pyrolysis. Carbon fibers
shows an unusual mechanical strength under a tensile load.
 These carbon fibers are used to increase the mechanical strength of electrical
contacts which are subject to under compressive or tensile loads during
operation.
 These carbon fibers also reduce the wear and tear of electrical contacts.
Moreover, carbon being a conductor of electricity, contributes for carrying
current passing through electrical contact in terms it reduces the contact
resistance.
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5. Carbon Use for Making Resistors
 High resistivity, high melting point and low temperature coefficient of
resistance make the carbon suitable for manufacturing resistors.
 Resistors made of carbon are widely used in electronic circuits.
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6. Carbon Use for Making Brushes for Electrical DC
Machines and Alternators
 Graphite Carbon is very much suitable for making brushes for large rating DC
machines and alternators. Brushes made graphite carbon are having following
advantages –
 Graphite Carbon brushes are having high contact resistance. This high
resistance of graphite carbon brushes helps to improve commutation.
 High thermal stability – which make them suitable to withstands at high
temperature developed due friction during operation of rotating machine.
 Self-lubrication between stationary brushes and rotating commutator or slip
rings. Which reduces the wear and tear of commutator or slip rings.
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7. Carbon Use for Making Dry Cell Elements
 Carbon is an important element of construction of dry cells.
 Carbon is used for making electrodes for zinc-carbon batteries (Dry cells).
 Carbon electrode works as positive pole of battery.
 In dry cells the carbon is an inert material as it does not take part in electro-
chemical reaction occurring in dry cells.
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8. Carbon Electrodes Use for Electric Furnaces
 Graphite carbon is widely used for manufacturing the electrodes for Electric
Arc furnaces.
 In Electric Arc furnaces used for steel production the operating temperature
level is about 2760oC.
 Graphite carbon is only commercial available material which has the high level
of electrical conductivity and ability to with stand with such high level of
temperature.
 Which make it suitable for making electrodes for electric arc furnaces.
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9. Graphite Carbon Use for Arc Lighting and Welding
Electrodes
 Graphite carbon is also widely used for manufacturing the electrodes for Arc
lighting and welding.
 As discussed above, graphite carbon has the high level of electrical conductivity
and ability to with stand at high level of temperature during Arc lighting and
welding.
 Which make it suitable for making electrodes for Arc lighting and welding.
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10. Carbon use as Component of Vacuum Valves and Tubes
 In vacuum valves and tubes, carbon is used for coating of cathode and grid to
protect against mechanical deformation produced at very high temperature
produced during operation of vacuum vales and tubes.
 In high power application, the anode used in vacuum valves and tube, must be
capable to withstand at high operating temperature and must be capable to
dissipate the heat produced.
 For this purpose carbon is very much suitable for making anodes for vacuum
valves and tubes.
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11. Carbon use for Makings Parts for Telecommunication
Equipments
 Carbon is used for making transducers such as microphones which converts the
sound to electrical signal.
 Before development of vacuum tube based amplifiers, the carbon-microphones
were the only practical means for obtaining high level audio signals.
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12. Thank You
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