In Inductive Circuit, Why the Circuit Current (I) Decreases, When Inductance (L) or Inductive reactance (XL) Increases?
Another question from electrical and electronics engineering interviews question and answers series.
Explain the statement that ” In an Inductive circuit, when Inductance (L) or inductive reactance (XL) increases, the Circuit Current (I) decreases“.
We know that in DC circuits:
I = V / R,
But in case of AC circuits:
I = V / Z
Where “total resistance of AC circuits = Impedance = Z = √ (R2 + (XL – XC2)”
In case of Inductive circuit:
- Z = √ (R2 + XL2)
- I = V / XL or I = V / Z
It shows that in inductive circuit, Current is inversely proportional to the inductive reactance as well as inductance “L” as inductance and inductive reactances “XL” are directly proportional to each others.
Let’s check with an example to see how current reduced by inductive reactance.
When Inductance = 0.02 H
Suppose an inductive circuit where:
- Inductance = L = 0.02 Henry
- Voltage = V = 220 V
- Resistance = R = 10 Ω
- Frequency = f = 50 Hz
To find the inductive reactance;
XL = 2πfL
XL = 2 x 3.1415 x 50 x 0.02
XL = 6.28 Ω
Now circuit impedance:
Z = √ (R2 + XL2)
Z = √ (102 + 6.282)
Z = 11.8 Ω
Finally, current in inductive circuit:
I = V / Z
I = 220 V / 11.8 Ω
I = 18.64 A
- Why Power Factor Decreases When Inductance or Inductive Reactance Increases?
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When Inductance = 0.04 H
Now we increased the Inductance (L) of inductor form 0.02 H to 0.04 H,
V = 220 V, R = 10 Ω, L = 0.04 H, f = 50 Hz.
XL = 2πfL= 2 x 3.1415 x 50 x 0.04 = 12.56 Ω
Z = √ (R2 + XL2) = √ (102 + 12.562) = 16.05 Ω
I = V / Z = 220 V / 16.05 Ω
I = 13.70 A
- In a Capacitive Circuit, Why the Current Increases When Frequency Increases?
- In an Inductive Circuit, Why the Current Increases When Frequency Decreases?
We can see that, When inductance (L) was 0.02 Henry, then circuit current were 18.64 A,
But when circuit inductance increased from 0.02 H to 0.04 H, then the current decreased from 18.64 A to 13.70 A.
In an inductive circuit, when inductive reactance XL increases, the circuit current decreases and vice versa.
In oral or verbal,
- Inductive reactance is a kind of resistance. When resistance increases, the circuit current decreases and vice versa.
- Inductance is directly proportional to the inductive reactance
L ∝ XL
- Current is inversely proportional to the inductance and inductive reactance.
I ∝ 1/L and I ∝ 1/XL
- Why Flux in Primary and Secondary Winding is Always Equal?
- Why the reactance of a system under fault condition is low and faults currents may raise to the dangerously high value?
- Why Inductive Reactance (XL In DC Supply Is Zero (0)?