À MODEL TRANSFORMER CIRCUIT
Finding the inductance of a transformer Primary by the following steps.
Requirement Steps
1. Measure Resistance of Primary Coil
R = 300 Ohms
In the real circuit, transformer coil has
resistance which is not accounted in the
simulation model. Hence a resistor be
added with assumed value or Measure it
from a real transformer that we want to
analyze. In this case 300 Ohms
2. Measure Voltage Input of Primary
Vp = 312 x 0.707 = 220v (RMS)
If we are analyzing a real transformer,
measure it from your wall soçket with
multimeter test tool.
3. Apply Voltage ang measure Current on
Primary (while no load on Secondary).
Ip = 0.0243 Amp (RMS - No Load)
4. Identify or Measure Input Frequency
F = 60 Hz (some countries uses 50hz)
Let's Find Inductance of the Primary coil on with following steps:
1. Calculate Impedance:
Impedance Z = Vp/Ip
Impedance Z = 220/0.0243 = 9053.50 Ohm
Impedance is the combine resistance
of inductive, resistive, and capacitive
reaction in the circuit that resist flow of
current. In Transformer, there is at least two
reactance. The Resistance of wire, and the
reactive effect of the coiled wire which act
as Inductor once an AC current flows in the
coil. Hence Impedance Z² = XL² + R²
2. Calculate Inductive Reactance of coil (XL):
Impedance: Z² = XL ² + (R - Xc) ² ,
No capacitive Reactance hence Xc=0:
So circuit impedance Z² = XL ² + R ²
XL = √ ( Z² - R³)
XL = √ (9053.50² - 300²) = 9048 Ohm
What we did here is we simply subtract
The reactive Resistance R² to the
impedance Z² to get the inductive
reactance XL.
3. Knowing the Inductive reactance XL of the
coil, we can now calculate the Inductor
value of the Primary coil (Lp).
Using Reactance Formula.
XL = 2π x f x Lp
Or...
Lp = XL / 2 π f
Lp = 9048 Ohms/ (2 x π x 60Hz)
Lp = 24 Henry (Same as Simulated Value)
