HOW TO TEST TRANSFORMER with Multimeter
TRANSFORMER TESTING Transformer consists of 2 winding ; primary winding and secondary winding. Transformer is the important device on power supply circuit. It convert high voltage to low voltage and provide safety feature as isolation between input and output , Isolation between high AC voltage and low AC voltage can achieve by transformer. This article explain basic transformer testing.
Step to test transformer with Digital Multimeter.
1. Turn equipment off ( unplug ) or remove power source from transformer under test.2. Turn rotary switch to resistor test function.
3. Connect test leads to primary winding.
Good transformer get measured resistance value.
Bad transformer ( open winding ) meter display " OL "
Bad transformer ( short turns ) meter display 0 ohm or very much low resistance.
4. Connect test leads to secondary winding.
Good transformer get measured resistance value.
Bad transformer ( open winding ) the meter display " OL "
Bad transformer ( short turns ) meter display very much low resistance.
Test primary winding , display resistance value.
Bad transformer display " OL" (for open ).
Test secondary winding ,display resistance value.
Bad transformer display " OL" (for open ).
Bad transformer display very much low resistance (for short ).
5. Test transformer core with primary winding. ( Isolation testing)
Connect test leads to transformer core and primary winding.
Good transformer meter display " OL "
Bad transformer meter display some resistance (leak)
6. Test transformer core with secondary winding. ( Isolation testing)
Connect test lead to transformer core and secondary winding.
Good transformer meter display " OL "
Bad transformer meter display some resistance (leak).
Test transformer core with secondary winding ( isolation testing).
Bad transformer display very much low resistance (for short ).
Bad transformer display " OL" (for open ).
Bad transformer display very much low resistance (for short ).
5. Test transformer core with primary winding. ( Isolation testing)
Connect test leads to transformer core and primary winding.
Good transformer meter display " OL "
Bad transformer meter display some resistance (leak)
6. Test transformer core with secondary winding. ( Isolation testing)
Connect test lead to transformer core and secondary winding.
Good transformer meter display " OL "
Bad transformer meter display some resistance (leak).
Test transformer core with primary winding ( isolation testing).
Good transformer meter display "OL"
Bad transformer (leak) meter display some resistance value.
Good transformer meter display "OL"
Bad transformer (leak) meter display some resistance value.
Good transformer meter display "OL"
Bad transformer (leak) meter display some resistance value.
7. Test isolation between primary winding and secondary winding.
Connect test leads to primary winding and secondary winding.
Good transformer meter display " OL ".
Bad transformer (leak) meter display some resistance.
Test isolation between primary winding and secondary winding.
Good transformer meter display "OL"
Bad transformer (leak) meter display some resistance value.
Step to test transformer with Analog Multimeter.
1. Turn equipment off ( unplug ) or remove power source from transformer under test.
2. Turn rotary switch to resistor test function , Rx1 range.
3. Connect test leads to primary winding.
Good transformer get measured resistance value.
Bad transformer ( open winding ) the pointer point at " ∞ ".
Bad transformer ( short turns ) the pointer point at 0 ohm.
4. Connect test leads to secondary winding.
Good transformer get measured resistance value.
Bad transformer ( open winding ) the pointer point at " ∞ ".
Bad transformer ( short turns ) the pointer point at 0 ohm.
5. Test transformer core with primary winding. ( Isolation testing).
Turn rotary switch to Rx10K range test function.
Connect test lead to transformer core and primary winding.
Good transformer the pointer point at " ∞ ".
Bad transformer (leak) the pointer show some resistance value.
6. Test transformer core with secondary winding. ( Isolation testing).
Connect test lead to transformer core and secondary winding.
Good transformer the pointer point at " ∞ ".
Bad transformer (leak) , the pointer point at some resistance value on scale.
Test transformer core with primary winding ( Isolation testing ).
Good transformer , the pointer must point at " ∞ ".
7. Test isolation between primary winding and secondary winding.
Connect test leads to primary winding and secondary winding.
Good transformer , the pointer point at " ∞ ".
Bad transformer , the pointer point at some resistance value on scale.
7. Test isolation between primary winding and secondary winding.
Connect test leads to primary winding and secondary winding.
Good transformer meter display " OL ".
Bad transformer (leak) meter display some resistance.
Good transformer meter display "OL"
Bad transformer (leak) meter display some resistance value.
Step to test transformer with Analog Multimeter.
1. Turn equipment off ( unplug ) or remove power source from transformer under test.
2. Turn rotary switch to resistor test function , Rx1 range.
3. Connect test leads to primary winding.
Good transformer get measured resistance value.
Bad transformer ( open winding ) the pointer point at " ∞ ".
Bad transformer ( short turns ) the pointer point at 0 ohm.
4. Connect test leads to secondary winding.
Good transformer get measured resistance value.
Bad transformer ( open winding ) the pointer point at " ∞ ".
Bad transformer ( short turns ) the pointer point at 0 ohm.
Test primary winding, use Rx1 range ,
meter display some resistor for good transformer.
meter display some resistor for good transformer.
Test secondary winding, use Rx1 range ,
meter display some resistor for good transformer.
5. Test transformer core with primary winding. ( Isolation testing).
Turn rotary switch to Rx10K range test function.
Connect test lead to transformer core and primary winding.
Good transformer the pointer point at " ∞ ".
Bad transformer (leak) the pointer show some resistance value.
6. Test transformer core with secondary winding. ( Isolation testing).
Connect test lead to transformer core and secondary winding.
Good transformer the pointer point at " ∞ ".
Bad transformer (leak) , the pointer point at some resistance value on scale.
Good transformer , the pointer must point at " ∞ ".
Test transformer core with secondary winding ( Isolation testing ).
Good transformer , the pointer must point at " ∞ ".
Good transformer , the pointer must point at " ∞ ".
Connect test leads to primary winding and secondary winding.
Good transformer , the pointer point at " ∞ ".
Bad transformer , the pointer point at some resistance value on scale.
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