Single Phase Induction Type Energy Meter

1. EEM PRESENTATION ON INDUCTION TYPE ENERGY METER PRESENTED BY -

2. (Single Phase Induction Meter) Introduction -

3. Construction - Driving system, Moving system, Braking syatem , and R egistering system

4. Theory & Operation - (Working)

5. ( Phasor Diagram of Single Phase Induction Type Energy Meter)

6. Let , V = applied voltage I = load current ϕ = phase angle of load I P = pressure coil current Δ  = phase angle between supply voltage and pressure coil flux f = frequency Z = impedence of eddy current paths α = phase angle of eddy current paths E ep = eddy emf induced by flux Φ p I ep = eddy current due to flux Φ p E es = eddy emf induced by flux Φ s I es = eddy current due to flux Φ s Net driving torque, T d ∝ Φ p Φ s (f/Z) sin β cos α T d = K 1 Φ p Φ s (f/Z) sin β cos α Where ,k 1 = a constant, β = phase angle between fluxes Φ p and Φ s , Φ s = ( Δ - ϕ )

7. Thus , Driving Torque , T d = K 1 Φ p Φ s (f/Z) sin ( Δ - ϕ ) cos α But Φ p ∝ V and Φ s ∝ I, ∴ T d = K 2 V I (f/Z) sin( Δ - ϕ ) cos α For constants f , Z and α , T d = K 3 V I sin( Δ - ϕ ) If N is the steady speed, braking torque T b = K 4 N At steady speed , driving torque = braking torque, ∴ K 3 V I sin( Δ - ϕ ) = K 4 N Thus , N = K V I sin( Δ - ϕ ) and for Δ = 90 ° i.e., N = K V I sin(90 ° - ϕ )

8. N = K V I cos ϕ Now V I cos ϕ = P (Power) Or N = K x (Power ) Total number of revolutions = ∫ N dt = K x ∫ (Power ) dt = K x (energy)

9. Errors - Incorrect magnitude of fluxes, Incorrect phase angles, Changes in strength of brake magnet, Changes in disc resistance, Abnormal friction of moving parts Adjustments - Preliminary light load adjustment, Light load adjustment, Creep adjustment