How to test the eponymous side of a common mode inductor

This can be considered in terms of both common mode and differential mode.

There are three types of measurement methods that we usually use:

1. DC resistance measurement method: use the resistance level of the multimeter to measure the DC resistance value of the antenna coil, oscillation coil, mid-perimeter, and input and output transformer coils, and you can judge the quality of these inductive components. When measuring the antenna coil and oscillation coil, the range should be set to r 10 gear; When measuring the mid-cycle and the output and input transformer, the range should be placed in the R 10 or R 100 gear; The measured resistance value is compared with the maintenance data and the daily experience data accumulated by oneself, and if it is very close, it means that the measured component is normal.

If the resistance value is much smaller than the empirical data, it indicates that there is a local short circuit in the coil; If the gauge hand indicates that the resistance value is zero, it means that the coil is short-circuited;

2. Power-on inspection method: the power transformer can be energized to check whether the secondary voltage drops, if the secondary voltage decreases, it is suspected that the secondary (or primary) has a local short circuit. When the transformer is quickly hot or has a burning smell or smoke after power-on, it can be judged that the transformer must have a local short circuit, which is not suitable for measurement at this time.

3. Instrument inspection method: you can use a high-frequency Q meter to measure the inductance and its Q value, and you can also use an inductance short-circuit meter to judge the local short-circuit phenomenon of the low-frequency coil. With a megohmmeter, the insulation resistance between the primary and secondary stages of a power transformer can be measured.

Some friends will say, if I have a non-professional single-piece measurement in my hand, and I only have simple equipment such as a multimeter on hand, then what should I do, can I still measure? Yes, the indirect measurement methods listed below are recommended

The inductive reactance of the inductance coil is z=2 fl

The DC resistance r of the inductor coil can be measured directly with a multimeter.

Then the total impedance z total = [r 2 + (2 fl) 2] under the root number

The coil is connected to the 220 volt 50 Hz mains, and the multimeter measures the circuit current i, which is totaled by i=u z.

The total impedance z = u i (u = mains voltage 220 volts, i is measured).

Bring the data into the formula z-total = [r 2 + (2 fl) 2] under the root number

The "inductance of the inductance coil l" can be obtained

If the coil inductance is too small to be directly connected to the 220-volt mains, a small transformer can be used to step down the mains and then connect it. The actual input voltage of the coil can still be measured with a multimeter.

The magnitude of the error of the obtained inductance mainly depends on the measurement accuracy of the multimeter, and there is no problem in principle.

There are several ways to do this:

Test directly with a comprehensive tester.

Judging by the hypothetical method, if it is the end of the same name, the inductance between the test pins of the short-circuit pin will be the largest. On the contrary, the inductance will be much smaller.

From this ** view, the easiest way is to see if the lead pins are on the same side, such as your ** look, the feet are on the same side outside, so or the end of the same name.

The above statement is only a personal opinion, welcome to verify, thank you!