This case study describes the key components of an electric transmission substation. It discusses transformers that change voltage levels, conductors that transmit electricity, insulators that prevent arcing, isolators for safety during maintenance, busbars for distributing power, lightning arresters for overvoltage protection, and circuit breakers for interrupting faults. The document provides details on the working principles and applications of these various substation equipment.
3. INTRODUCTION
ELECRIC SUBSTATION : Part of an electrical, generation ,
transmission ,distribution system . Here voltage gets
transforms from low to high or high to low(generally).
Between generation to consumption various sub station may
involve, at various level
May be public or private owned
May be of several types of substations ; transmission, pole,
switching , distribution e.t.c.
4. This case study is based on TRANSMISSION SUBSTATION
so important components used here are as follows,
ELECTRICAL POWER TRANSFORMERS
INSTRUMENTS TRANSFORMERS
CONDUCTORS
INSULATORS
ISOLATORS
BUS BARS
LIGHTNING ARRESTERS
CIRCUIT BREAKERS
ELECTRICAL PANELS
6. ELECTRICAL POWER TRANSFORMERS
• A STATIC ELECTRICAL MACHINE USED TO TRANSFORMS
LOW VOLTAGE TO HIGH OR VICE VERSA.
• WORKING PRINCIPLE BASED ON FARADAY LAW OF
ELECTROMAGNETIC INDUCTION ( a varying current in
one coil produces varying magnetic field which in turn
induces voltage in other coil)
13. INSTRUMENT TRANSFORMERS
CURRENT TRANSFORMERS
VOLTAGE TRANSFORMERS
Instrument transformers scale the large values of voltage or current to
small, standardized values that are easy to handle for instruments
and protective relays.
. This is because measuring meters or instruments and protective relays
are low voltage devices, thereby cannot be connected directly to high
voltage circuit for the purpose of measurement and protection of the
system.
A current transformer provides a secondary current that is accurately
proportional to the current flowing in its primary.
The current transformer presents a negligible load to the primary circuit.
Current transformers are the current sensing units of the power system.
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16. CONDUCTORS
The material that allows the flow of electric charge is called conductor.
Conductors permit free movement of the flow of electrons through them.
These are used for the transmission of power or electrical energy.
Conductors are of different types and mostly aluminum conductors are
preferred in practical power systems.
Al 61% of conductivity than Cu.
But has 30 % weight of copper.
Bare wire of Al weighs half of Cu of same resistance.
18. INSULATORS
An electrical insulator is a material whose internal electric charges do not
flow freely
Insulators used for high-voltage power transmission are made
from glass, porcelain or composite polymer materials.
Strain insulator
Suspension insulator
19. ISOLATORS
Isolator switch is used to ensure that an electrical circuit is completely de-
energized for service or maintenance.
The disconnector is usually not intended for normal control of the circuit,
but only for safety isolation.
Disconnectors can be operated either manually or automatically.
Disconnectors lack a mechanism for suppression of electric arcs.
They are off-load devices.
Disconnectors have provisions for a lockout-tagout so that inadvertent
operation is not possible.
20. LIGHTNING ARRESTER
A lightning arrester is a device used on electrical power systems to protect
the insulation and conductors of the system from the damaging effects
of lightning.
If protection fails or is absent, lightning that strikes the electrical system
introduces thousands of kilovolts that may damage the transmission lines, and
can also cause severe damage to transformers and other electrical or
electronic devices.
USED BOTH SIDE OF TRANSFORMER
These prevent the flow of the normal power or signal currents to ground, but
provide a path over which high-voltage lightning current flows bypasses to
earth.
connected parallel to device to be protected
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25. BUSBARS
A busbar is a metallic strip or bar, typically housed inside switchgear, panel
boards, and busway enclosures for local high current power distribution.
They are also used to connect high voltage equipment at electrical
switchyards, and low voltage equipment in battery banks.
They are generally uninsulated, and have sufficient stiffness to be supported
in air by insulated pillars.
These features allow sufficient cooling of the conductors, and the ability to
tap in at various points without creating a new joint.
It can be used outside
26. CIRCUIT BREAKERS
Vacuum interrupter is a switch which uses electrical contacts in a vacuum.
It is the core component of medium-voltage switches.
Separation of the electrical contacts results in a vacuum arc, which is quickly
extinguished.
The separation of contacts causes the release of vapour which is filled in the
contact space. It consists positive ions liberated from contact material.
The vapour density depends on the current in the arc. When the current
decreases, the rate of vapour release decreases and after current zero.
Medium regain its dielectric strength if the vapour density is reduced.
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28. CONCLUSION
VARIOUS ELECTRICTAL SYSTAMS ARE WONDERFULLY CONTRIBUTING TO
TRANSMISSION AND DISTRIBUTION SYSTEMS
KNOWING THE SAFETY PRECAUTION TAKEN DURING WORKING
MAINTAINING THE HEALTH OF EQUIPMENT IS VERY NECESSARY
