How to judge the quality of the motor coils

Update:19-01-2020
Summary:

When selecting and using the induction coil of a motor, […]

When selecting and using the induction coil of a motor, we must first think of the inspection and measurement of the coil, and then judge the quality of the coil and its quality. To accurately detect the inductance and quality factor Q of an inductance coil, special instruments are generally required, and the test method is more complicated. In actual work, such detection is generally not performed, and only the on-off check of the coil and the judgment of the Q value are performed. The DC resistance of the coil can be measured by using a multimeter resistance file, and then compared with the originally determined or nominal resistance. If the measured resistance is much larger than the originally determined or nominal resistance, the pointer may not move. (The resistance value tends to infinity X) It can be judged that the coil is disconnected; if the measured resistance value is extremely small, it is judged that it is a severe short circuit or a local short circuit which is difficult to compare. In both cases, it can be determined that the coil is bad and cannot be used.

If the detection resistance is not significantly different from the originally determined or nominal resistance value, it can be judged that this coil is good. In this case, we can judge the quality of the coil, that is, the value of the Q value, according to the following situations. When the inductance of the coil is the same, the smaller the DC resistance, the higher the Q value; the larger the diameter of the wire used, the larger the Q value; if the multi-strand winding is used, the more the number of wires, the more the Q value High; the smaller the loss of the material used in the coil bobbin (or iron core), the higher its Q value. For example, when a high-silicon silicon steel sheet is used as an iron core, its Q value is higher than when an ordinary silicon steel sheet is used as an iron core; the smaller the coil distributed capacitance and magnetic leakage, the higher its Q value. For example, the coil of the honeycomb winding method has a higher Q value than that of the flat winding, and a higher value than the random winding; the coil has no shielding cover, and there is no metal member around the installation position, and the Q value is higher. Conversely, the Q value Lower. The closer the shield or metal member is to the coil, the more serious its Q value decreases; the position with the magnetic core should be properly arranged and reasonable; the antenna coil and the oscillating coil should be perpendicular to each other, which avoids the influence of mutual coupling.