Determination of Transformation Ratio
of a Single Phase Transformer
Experiment No. : 5
Experiment Name :
Determination of Transformation Ratio of a
Single Phase Transformer.
Objective:
To determine transformation ratio of a single
phase transformer.
Theory:
Transformer is a static electrical a.c. powered
device, which transfer the electrical power from
one circuit to another circuit without changing its
frequency.
The level of voltage may be stepped up or down
depending upon the number of turns on low
voltage side winding and high voltage side
winding. If we connect the ac power supply with
low voltage side winding, then the winding is
considered as Primary Side. And the remaining
winding, i.e. high voltage winding, from which
we take power output, is considered as
Secondary Side.
And if we connect the ac power supply with high
voltage side winding, then the winding is
considered as Primary Side. And the remaining
winding, i.e. low voltage winding, from which we
take power output, is considered as Secondary
Side.
So, there is a ratio, depending on which, the
level of voltage is stepped up or down, that is
called, Transformation Ratio.
The transformation ratio is defined as the ratio
of secondary voltage to primary voltage. The
transformation ratio is indicated as K.
If the value of K is


greater than 1. Then the transformer is step
up Transformer
less than 1. Then the transformer is step
down Transformer
equal to 1. Then the transformer is isolator
Transformer
As, K is the ratio of two same quantity, so it is
unitless.
Circuit Diagram:
Observation Table:
Primary
Sl.No. Voltage
(V1) volt
Secondary
Voltage (V2)
volt
Transformation
Ratio
Remarks
(K= V2 / V1 )
1.
230
124.7
0.54
Step down transformer
2.
115
212.9
1.85
Step up transformer
Apparatus Used:
Sl.
No.
Name of the
Quantity
Apparatus
Specification
1.
Single phase
1
Transformer
230/115
V,
Shell type, Air
cooled
2.
Digital
Multimeter
0-10 MΩ, 0Akademika
750 V, 0-10 A
1
Maker’s Name
Remarks:
The transformation ratio is calculated by
measuring the primary voltage and secondary
voltage.