EEM PRESENTATION

ON INDUCTION TYPE ENERGY METER

PRESENTED BY -

(Single Phase Induction Meter)

Introduction -

Construction -

Driving system, Moving system, Braking syatem, and Registering system

Theory & Operation -

(Working)

(Phasor Diagram of Single Phase Induction Type Energy Meter)

Let , V = applied voltage I = load current ϕ = phase angle of load IP = 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 Eep = eddy emf induced by flux Φp

Iep = eddy current due to flux Φp

Ees = eddy emf induced by flux Φs

Ies = eddy current due to flux Φs Net driving torque,Td ∝ Φp Φs (f/Z) sinβ cosαTd = K1 Φp Φs (f/Z) sinβ cosαWhere ,k1 = a constant,β = phase angle between fluxes Φp and Φs ,Φs = (Δ- ϕ)

• Thus , Driving Torque , Td = K1 Φp Φs (f/Z) sin(Δ- ϕ) cosα

• But Φp V and ∝ Φs I,∝

• ∴ Td = K2 V I (f/Z) sin(Δ- ϕ) cosα

• For constants f , Z and α ,

• Td = K3 V I sin(Δ- ϕ)

• If N is the steady speed, braking torque• Tb = K4 N

• At steady speed , driving torque = braking torque,

• ∴ K3 V I sin(Δ- ϕ) = K4 N

Thus, N = K V I sin(Δ- ϕ) and for Δ = 90°i.e., N = K V I sin(90°- ϕ)

• 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)

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