Can make use of universal DC resistance of flat coil resistance profile measuring table flat coil coil volume, compared with the original that the resistance value or nominal resistance, if the measured resistance value than the original value or standard flat coil said that flat coil resistance increases, and the pointer does not move (resistance tends to infinity X can distinguish the coil break; if the measured resistance is minimal, that is serious short fruit million local short circuit is difficult to compare the two kinds of situation emerged, can be concluded that the flat coil to coil is bad, can not be used. If the resistance is not the same as that of the original or nominal flat coil, it can be concluded 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 the Q value. The phase inductance coil, the DC resistance is small, the higher the Q value; the wire diameter is larger, the larger Q value; if the selection of Multi Strands winding, the more number of wires of the flat coil, the higher the Q value; the coil frame (or core) for data loss the smaller, the higher Q value. For example, when a high silicon steel sheet is used as an iron core, the Q value is higher than that of a general silicon steel sheet; the more the coil distribution capacitance and the leakage flux are, the smaller the coil is, and the higher the Q value. For example, the coil of the honeycomb winding method has a higher Q value, higher winding time and higher volume than a random winding; the coil has no shield; when the metal component is positioned around the azimuth, the Q value is higher; on the contrary, the Q value is low. The nearer the off line of shield or metal component is, the more severe the decrease of Q value; the high frequency coil with magnetic core has higher Q value than the magnetic core; the smaller the magnetic core is, the higher the Q value is.
In the power filter, the low frequency choke is not very important in Q value, but the magnitude of inductance L affects the filtering greatly. Attention should be paid to that the low frequency choke has more direct DC in use. In order to avoid the magnetic fullness, the iron core is required to be inserted in order to make it have larger air gap. In order to avoid the breakdown of the coil and core, the insulation between the two shall comply with the request. Therefore, the insulation resistance between the coil and the core should be examined before use. The specific method is the same as that of the transformer insulation resistance (see the transformer).
As for the high frequency flat coils, the inductance L is more difficult to test because it is usually adjusted according to the application of the circuit to determine whether the inductance is suitable. A plurality of winding coils, but also with a multimeter check coil windings is not between short-circuit; with coil iron core and the metal shield, to measure its winding and iron core or metal shield is not short.
