How to learn inductance of the coil

How to learn inductance of the coil

The more inductance of the coil, the better it detains alternating current and sharp impulses, at the same time without preventing course of constant. It is possible to measure this parameter in the indirect way.


1. Find the active resistance of the coil. For this purpose use a usual ohmmeter. After its connection wait about a second that transition processes came to the end. Only after it read instrument readings. At connection and shutdown of the measuring device do not concern any current carrying parts: even if ohmmeter supply voltage is also small, at the moments of sharp change of current via the coil there can be self-induction impulses. Transfer the measured active resistance to ohms.

2. Turn on consistently the generator of a sinusoidal signal, the milliamperemeter of alternating current showing it operating, but not amplitude value, and the coil. Parallel to the output of the generator attach the voltmeter of alternating voltage which is also measuring it acting, but not amplitude value. Turn on the generator and measure tension and current. Then switch off the generator and sort a chain. At the switched-on generator and within the first second after its shutdown also do not concern current carrying parts even if measuring tension is not enough.

3. Divide the measured tension into the measured current, previously having transferred these sizes to the SI system. You learn the sum of inductive and active resistance of the coil. It will be expressed in ohms.

4. Subtract from total resistance active, and it will turn out inductive. On it calculate inductance, having used the following formula: L=Xl / (2πf), where L - inductance, (henry); Xl is inductive resistance, Ohm; f - frequency, Hz; π - number of Pi. If necessary transfer result of measurement to more convenient units: millihenry or microhenry. Consider that in this way it is impossible to separate a capacitive component of reactive resistance from inductive, but in most cases the parasitic capacity of the coil can be neglected.

Author: «MirrorInfo» Dream Team