Exact Voltage Drop of a Transformer

How to Calculate the Exact Voltage Drop of a Transformer?

Transformer voltage drop is important to know because it is one of the factors that affect the performance of an electrical system where it is installed. 

There are two most common methods to calculate the transformer voltage drop-

1. Approximate Method;
2. Exact Method.

The Approximate Method of Transformer Voltage drop calculation in details is explained in another article.

Let's explain the Exact Method of Transformer voltage drop calculation below:

where:

E_VD – Voltage drop, line-to-neutral, volts

Es – Source voltage, line-to-neutral, volts

I – Line (Load) current, amperes

R – Circuit (branch, feeder) resistance, ohms

X – Circuit (branch, feeder) reactance, ohms

cosθ – Power factor of load, decimal

sinθ – Reactive factor of load, decimal

Transformer voltage drop:

Exact method If the receiving end voltage, load current and power factor (PF) is known.

E_R is the receiving end voltage.