How to measure check the good transformer ?kindly if anyone might upload the video for me . in this regarddo we have to take it out of the board ? (isolate from other components) .what to check . what should be the values ?when checking , supply should keep on or not ?any website that explain these things and upload the videos in these kind of matters . I want to learn the repairing and maintenance of electronic electrical devices instruments of daily use ?thanksGOD BLESS YOU ALL
If you mean a power transformer that is used in large industries, then there is a big list of tests to ensure the healthiness of the transformer. There are no videos. may be you please mail me and I would send you the list of tests.
cutting-edge transformers are rated via cutting-edge, no longer voltage. to objective it, positioned a typical cutting-edge interior the direction of the hollow (accepted) with the the final option termination resistance around the secondary and diploma the secondary voltage. The secondary voltage would desire to be near to (Ip/N)Rsec.
You should compare the readings and current drawn off load with a similar transformer that is known to be good, do this, Measure the off load current at the primary with the secondary terminals disconnected, all current drawn will be due to hysteresis loss and any shorted turns. Measure the output voltage off load. Do this with both the suspected and the identical 'known to be good' transformer and expect similar results. For a double wound isolating transformer, also check for electrical separation between primary and secondary windings. Should be in the order of megohms.
A quick-and-dirty check is to measure the resistance of the windings. There is no correct value because every transformer is different. For a mains step-down transformer normally the primary windings will be 50 ohms and the secondaries will be a few ohms. If there are double windings (like 0-115 0-115 on the primaries) then both windings should have a similar resistance. This is not a guarantee of a good transformer because it will not detect shorted turns. The only way to detect that is to take the transformer out, power it and measure the output voltages.
