How to judge the quality of an inductor?

1. Visual inspection

Directly observe whether the lead of the inductor is disconnected, whether the magnetic core is loose, whether the insulating material is damaged or burnt, etc.

2. Multimeter testing

In the judgment of the quality of the inductor, a multimeter is often used to measure the continuity and resistance value of the inductor. Place the multimeter in the Ω block, and connect the red and black test leads to any lead end of the inductor. At this time, the pointer should swing to the right. According to the measured resistance value, the judgment can be divided into the following three situations.

(1) The resistance value of the inductor under test is too small. It indicates that the internal coil of the inductor has a short-circuit fault. Pay attention to the test operation, be sure to set the multimeter to zero first, and carefully observe whether the position where the pointer swings to the right actually reaches the zero position to avoid misjudgment. When it is suspected that there is a short-circuit fault inside the inductor, it is best to repeat the test several times with the R×1 Ω block, so that a correct judgment can be made.

(2) The measured inductor has a resistance value. The DC resistance value of the inductor is directly related to the diameter of the enameled wire used for winding the inductor coil and the number of turns. The thinner the wire diameter and the more turns, the greater the resistance value. Under normal circumstances, use a multimeter to measure R×1 Ω. As long as the resistance value can be measured, the measured inductor can be considered normal.

(3) The resistance value of the measured inductor is infinite. This phenomenon is relatively easy to distinguish, indicating that an open-circuit fault has occurred at the coil or terminal of the inductor and the coil contact.

3. Insulation detection

Insulation detection is mainly for inductors with iron cores or metal shields. Place the multimeter in the R*1K file and measure the resistance between the coil lead and the iron core or metal shield. Normally, it is infinite (the needle does not move), otherwise the inductor is poorly insulated.

Note: When measuring a coil with a very small inductance, it is good as long as the two ends of the measuring coil are electrically blocked.

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