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Aziz Ahmad Haider
Reg # 2011-EE-458
What is an energy meter?
Why it is used?
What is the working Principle of the energy
Which Components are used in an energy
What are the Advantages and disadvantages
of usual energy meters?
What is the Solution for the drawbacks of
commonly used energy meters?
An energy meter is a device that measures the
amount of electrical energy consumed by
a residence, business, or an electrically
What is the energy?
Energy is the product of power and time for
which power is used i.e
Induction watt hour meter(Energy meter)
which are commonly used measure
electrical energy in KWH(killo watt-hour)
It involve four steps in it’s working
Energy meter has a moveable Aluminum disk
in it which is mounted on a vertical shaft.
The rotation of this disk is base of energy
When a load is connected poles of potential and
the current coils produces their magnetic field
because of flow of current which produce
resultant flux .
This resultant flux develops eddy current inside
the disk.So that disk starts to rotate as
“Current carrying conductor placed inside a
magnetic field will experience a force called
Why Breaking is require?
When the disk start to rotate it is under a
torque and that torque is depend upon current
in coil so for a large load their will be very
high torque and speed of the Aluminum disk
is also very high which produce different
mechanical loses(e.g go to run away, disk
become frictionless) therefore we require a
retarding torque to prevent from these loses.
For this purpose permanent magnets are used
in energy meter across the disk.
Working of permanent magnets
Flux of the permanent magnets is cut because of
motion of Al-disk that produce additional eddy
current. This eddy current will develop it’s own
torque that is opposite to the driving torque.
Retarding torque produced by permanent magnets is
directly proportional to speed of the disk so that
High for heavy loads and less for small loads.
At what speed disk rotates?
Disk should rotate on a speed value where
Driving torque=retarding torque
The amount of energy is being displayed by
using the mechanical counter which are in
couple with the shaft through a gear train.
How the mechanical counters
Incorrect magnitude of fluxes,
Incorrect phase angles,
Changes in strength of brake magnet,
Changes in disc resistance,
Abnormal friction of moving parts
To avoid disk resistance and abnormal
friction(appears with time) we have to
replace our meters after a specific time
duration for accurate reading.
For incorrect magnitudes of fluxes and
Phase angles we can use creep or low
Besides of replacing meters our adjust them
on low load we can use Smart Energy meters
Which are more accurate and also have long
life with no frictional loses.
Internal scheme of smart Energy
Benefits of Smart Energy meter
Low Current Performance
Low voltage performance
Difficult to temper