Pressure good judgment method

Transformer good or bad judgment method

It can measure its primary resistance, typically around 50-300 ohms, and the resistance between each winding is also infinite. The secondary resistance is measured in the same way, generally small, around 2-30 ohms, and the winding resistance between them is also infinite. Finally, the primary and secondary resistances can be measured, which is infinite.

Generally, a small power transformer has a smaller number of secondary coils. It is difficult to judge whether it is good or bad (by its turn-to-turn short circuit) by resistance measurement. It can be tested on a low-voltage power supply, and the voltage at both ends and the marked The voltages are proportional to each other, so it is easy to judge. Use the multimeter resistance file ~ measure the resistance of the transformer input two lines. What is the resistance between the two wires that measure the output of the transformer. Because I don't know what type of transformer you are, it's hard to say how much resistance! Anyway, there is a certain resistance is good, if there is no resistance or the circuit is broken!

The power transformer is good or bad, and it must be "good" through four steps of testing.

1, all the primary and secondary coils are not open. Generally, the low-power step-down transformer has a small and fine primary coil, so it is easy to break, and the secondary is thick and small, and rarely breaks. The primary resistance is generally in the range of tens to hundreds of ohms, and the smaller the power, the greater the resistance measured. 181 ohms, normal, estimated to be 4~5W transformer. The secondary resistance is much smaller and should be between a few ohms and a few ohms.

2, there is no short circuit between the primary and secondary coils, no leakage. With a multi-meter high-resistance file, the two meter pens are respectively connected to one of the primary and secondary coils, and the indication should be above several megaohms, and infinity is better.

3. The primary and secondary coils are not short-circuited with the iron core and do not leak electricity. Refer to point 2 measurement.

4. There is no short circuit between the primary and secondary coils. If the power is turned on at no load, the transformer will be abnormally hot. It is necessary to think of this reason. Moreover, the short circuit between turns can not be measured with a multimeter.