The lesson on measurements using the voltage and current transformer.

1. MEASUREMENT USING CURRENT AND
VOLTAGE TRANSFORMERS

2. MEASUREMENT USING CURRENT
AND VOLTAGE TRANSFORMERS
 Introduction.
 Current Transformer CT.
 Voltage Transformer VT.
 Difference between C.T. and V.T.
 Experiment (Use the voltage transformer and the current
transformer in the power measurement of the load ).
 Review.

3. Current Transformer CT
• Definition of Current Transformer(CT).
• Function of Current Transformer(CT).
• Examples of how to calculate turns ratio.

4. Examples1
250/5 A CT is used along with ammeter. If the
ammeter reading is 2.7 A, estimate the line
current.
𝑰𝒑
𝑰𝒔
=
𝑰𝟏
𝑰𝟐

5. Voltage Transformer (VT)
• Definition of Voltage Transformer(VT).
• Function of Voltage Transformer(VT).
• Examples of how to calculate turns ratio and ratio
error.

6. Examples 2
11000/100 V VT is used along with voltmeter. If
the voltmeter reading is 87.5 V, estimate the line
voltage
𝑽𝒑
𝑽𝒔
=
𝑽𝟏
𝑽𝟐

7. Examples 3
1000/5 A CT has no-load current of 38A. Calculate
the ratio error at full load.
ratio error =
Ip −(K×Is)
Ip
× 100

8. Difference between C.T. and V.T.
Current Transformer(CT). Voltage Transformer(VT).
Connected in series with power
circuit.
Connected in Parallel with Power
circuit.
Secondary is connected to
Ammeter.
Secondary is connected to
Voltmeter.
The current transformer works to
reduces the current for
measurement purposes.
The voltage transformer works to
reduce the voltage only for
measurement purposes.

9. Experiment