Operation of Single-Phase Energy Meters
The supply voltage is applied across the pressure coil. The pressure coil winding is highly inductive as it has a very large number of turns and the reluctance of its magnetic circuit is very small owing to the presence of air gaps of very small length. Thus the current I, through the pressure coil is proportional to the supply voltage and lags it by a few degrees less than 90°. This is because the winding has a small resistance and there are iron losses in the magnetic circuit.
Current I produce a flux. This flux divides itself into two parts, and. The major portion flows across the side gaps reluctance of this path is small. The reluctance to the path of flux is large and hence its magnitude is This flux, goes across the aluminum disc and hence is responsible for the production of driving torque. Flux is in phase with current I, and is proportional to it. Therefore flux is proportional to voltage V and lags it by an angle a few degrees less than 90°. Since flux o, is alternating in P nature, it induces an eddy emf in the disc which in turn produces an eddy current.
The load current I flow through the current coil and produces a flux ₁. This flux is proportional to the load current and is in phase with it. This flux produces eddy current I in the disc. Now the eddy current interacts with flux o, to produce a torque, and eddy current interacts with it to produce another ep torque. These two torques are in the opposite direction and the net torque is the difference.
Phasor Diagram of Energy Meter
Operation-of-Single-Phase-Energy-Meter
Let,
V = applied voltage
I = load current
Φ = phase angle of load
Ip = pressure coil current
del = phase angle between supply voltage and pressure coil flux
f = frequency.
Z = impedance of eddy current paths
α = phase angle of eddy current paths
Eep = eddy emf induced by flux Φp
Iep = eddy current due to flux Φp
Eev = eddy emf induced by flux Фs
Ies = eddy current due to flux Фs
Td ∝ Ф1 x Ф2 x f / Z x sinß x cosα = K1 x Ф1 Ф2 f / Z sinßcosα
where K1 = a constant
Now ß = phase angle between fluxes Ф₁ and Φ2
In our case, the two fluxes are Φp and Φs
ß = Phase angle between fluxes, Φp and Φs = (Delta – Ф)
Driving torque, Td = K1 Φp Φs f/Z sin(del – Φ) cos α
But Φp ∝ V and Φs ∝ Ι.
Td = K2 Φp Φs f/Z sin(del – Φ) cos α
If f, Z, and α are constants,
Td = K3 VI sin( del – Φ )
If N is the steady speed, braking torque
TB = K4 x N
At steady speed, the driving torque must equal the braking torque
K4 N = K3 VI sin( del – Φ )
or
N = KVI sin( del – Φ )
If Delta = 90°
Speed, N = KVI x sin(90 deg – Ф) = KVI x cosФ = K x (power)
The Speed of the rotation is directly Proportional to the power.
Thus so that the speed of rotation is proportional to power, angle del should be equal to 90°. Hence the flux Φp’ must be made to lag the supply voltage to be exactly 90°.
Total Number of revolution=[Tex]\int N dt=k\int VI sin(\Delta-\phi) [/Tex]
taking del=90°,total number of revolutions
=[Tex]k\int VI cos\phi dt [/Tex]
[Tex]=k\int power dt=k \times energy [/Tex]
So the three phase energy meter is used for measuring the large power Consumption.
Energy Meter
Energy meters play a crucial role in measuring and monitoring electrical energy consumption, enabling fair billing, promoting energy efficiency, and supporting the management of power distribution networks. These meters come in different forms, including analog, digital, smart meters, and advanced metering infrastructure (AMI). There are various types of energy meters, which have several functions. It is used for household or domestic purposes for measuring electricity bills. In this article, we will go through what is energy meter?, construction with its operations, Then we will go through its types and finally, we will conclude our article with its Advantages, Disadvantages, and characteristics.
Table of Content
- Energy Meter
- Construction and Working
- Operation
- Types
- Advantages and Disadvantages
- Characteristics
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