How To Identify Primary And Secondary Of Transformers

Introduction:

• The transformer is one of the most common devices found in electrical system that links the circuits which are operating at different voltages.
• These are commonly used in applications where there is a need of AC voltage conversion from one voltage level to another.
• It is possible either to decrease or increase the voltage and currents by the use of transformer in AC circuits based on the requirements of the electrical equipment or device or load.
• Various applications use wide variety of transformers including power, instrumentation and pulse transformers.

method #1: using multimeter

A

• First turn ON digital multimeter and select continuity mode.
• Connect the test leads to the Transformer terminals. Keep test leads connected for a few seconds at connection(A).
• Read the measurement value is displayed. If the Transformer value is within the measurement range, the multimeter will display the Transformer value.
• displayed multimeter value is between 300 to 700, this side is primary.
• displayed multimeter value is between 2 to 3, this side is secondary. 

B

• Connect the test leads to the Transformer another side terminals. Keep test leads connected for a few seconds at connection(B).
• Read the measurement value is displayed. If the Transformer value is within the measurement range, the multimeter will display the Transformer value.
• displayed multimeter value is between 300 to 700, this side is primary.
• displayed multimeter value is between 2 to 3, this side is secondary.

method #2:

• first see the centre tap transformer, if wire connection is 2 -this side is primary. else, wire connection is 3 -this side is secondary.

method #3:

• the transformer details is display at top side of the transformer or display primary or secondary side.