When selecting and using the inductance coil of the motor, we should first think of the inspection and measurement of the coil, and then judge the quality of the coil of the long axis motor. In order to accurately detect the inductance and quality factor Q of inductance coil, special instruments are generally needed, and the test method is more complex. In practical work, this kind of detection is generally not carried out, only the on-off inspection of the coil and the judgment of Q value are carried out.

The DC resistance of the coil can be measured by using the resistance gear of the multimeter, and then compared with the original determined resistance or nominal resistance. If the measured resistance is much larger than the original determined resistance or nominal resistance, or even the pointer does not move (the resistance tends to infinity x), the coil can be judged to be broken; If the measured resistance is very small, it is difficult to judge whether it is a serious short circuit or a local short circuit. If these two conditions occur, it can be judged that the coil is broken and cannot be used. If the difference between the measured resistance and the original or nominal resistance is small, it can be judged that the coil is good.

In this case, we can judge the quality of the coil according to the following conditions, that is, the size of Q value. When the inductance of the coil is the same, the smaller the DC resistance is, the higher the Q value is; The larger the diameter of the conductor, the larger the Q value; If the multi strand winding system is adopted, the more strands the conductor has, the higher the Q value will be; The smaller the loss of the material used in the coil framework (or core), the higher the Q value.

For example, when high silicon steel sheet is used as core, its Q value is higher than that when ordinary silicon steel sheet is used as core; The smaller the distributed capacitance and magnetic flux leakage, the higher the Q value. For example, the Q value of the honeycomb winding method is higher than that of the flat winding method, and higher than that of the random winding method; When the coil has no shield and there is no metal component around the installation position, the Q value is higher, on the contrary, the Q value is lower. The closer the shield or metal component is to the coil, the more serious the Q value decreases; The position of magnetic core should be properly arranged; The antenna coil and oscillation coil should be perpendicular to each other, which avoids the influence of mutual coupling.