The given figure represents the phasor diagram of:

This question was previously asked in

PGCIL DT Electrical 13 Aug 2021 Official Paper (NR I)

Option 3 : nominal π model

**Nominal π Method for Medium Transmission Line:**

- In this method, the capacitance of each conductor (i.e., the line to neutral) is divided into two halves.
- One half being lumped at the sending end and the other half at the receiving end as shown in Fig below.

It is obvious that capacitance at the sending end has no effect on the line drop.

However, its charging current must be added to line current in order to obtain the total sending end current.

Let,

I_{R} = load current per phase

R = resistance per phase

X_{L} = inductive reactance per phase

C = capacitance per phase

cos ϕ_{R} = receiving end power factor (lagging)

V_{S} = sending end voltage per phase

Taking the receiving end voltage as the reference phasor then, phasor can be drawn as,

Since, I_{C1} = jfCV_{R}

And, I_{C2} = jfCV_{S}

Consider, Y = jfC

∴ I_{C1} = YVR

And, I_{C2} = YVS

Hence, Phasor can be drawn as,