The local deformation of transformer winding deformation tester means that the total height of the coil has not changed, or the equivalent diameter and the thickness of the coil has not changed in a large area; Just part of the coil size distribution uniformity change, or part of a line of bread a small degree of the change of equivalent diameter, the total inductance coil basically remain unchanged, so the fault and normal phase spectrum curve in low frequency band of the first resonant peak point will overlap, as part of the size of the deformation area, the corresponding subsequent several resonance peak displacement will occur.

Transformer winding deformation tester

1. Local compression and opening deformation

The local compression and pull deformation of transformer winding deformation tester is generally believed to be caused by electromagnetic force, due to the repulsive force generated by the current in the same direction, when the two ends of the coil are pressed, the repulsive force will be the individual pad extrusion, causing part of the extrusion, and part of the pulled apart. Under the condition that both ends of the nail are not moved, this deformation generally does not affect the lead: this deformation generally only changes the distance between cakes (axial direction), in the equivalent circuit body is now on the parallel inductor (capacitor between cakes) change. Without the lead being pulled, the high frequency portion of the spectrum will vary very little. The whole coil is not compressed, only part of the distance between cakes is pulled apart, and part of the distance between cakes is compressed. As can be seen from the spectrum diagram, some resonant peaks move to the high frequency direction, accompanied by the peak decline; Some resonant peaks move to the low frequency direction and rise with the peak. The deformation area and deformation degree can be estimated by comparing the position of the resonant peak where the obvious movement is, (the number of peaks) and the movement of the resonant peak. When local compression and pull deformation affect the leads, the high frequency part of the spectrum will change. When the degree of local compression and open deformation is large, some resonant peaks of low frequency and middle frequency overlap, some peaks disappear, and some resonant peaks increase.

Two, interturn short circuit

If the coil occurs metallically inter-turn short circuit, the overall inductance of the coil will be significantly reduced, and the obstruction of the coil to the signal will be greatly reduced. Corresponding to the spectrum diagram, the resonant peak in the low frequency band will obviously move to the high frequency direction. At the same time, due to the reduction of obstruction, the frequency response curve will move to the direction of decreasing attenuation in the low frequency band, that is, the curve will move up by more than 2odB. In addition, as the value of Q decreases, the difference between the resonant peaks and valleys on the spectrum curve will decrease. The spectrum curves of the intermediate and high frequencies coincide with those of the normal coil.

Three, coil broken

When the coil is broken, the overall inductance of the coil will be slightly increased. Corresponding to the spectrum diagram, the resonant peak of the low frequency band will move slightly to the low frequency direction, and the attenuation of the amplitude is basically unchanged. The spectrum curves of the intermediate and high frequencies coincide with those of the normal coil.

Four, metal foreign bodies

In the normal coil, if there is a metal foreign body in the cake, although it has little effect on the low-frequency total inductance, the capacitance between the cakes will increase. The resonant peak of the low-frequency part of the spectrum curve will move to the low-frequency direction, and the amplitude of the medium-high frequency part of the curve will increase.

5. Lead displacement

When the lead displacement occurs, the inductance is not affected, so the low frequency band of the spectrum curve should be completely coincident, and only the curve in the 2ookHz~5ookHz part changes, mainly in the attenuation amplitude. When the lead line moves toward the shell, the high frequency part of the spectrum curve moves toward the direction of increasing attenuation, and the curve moves down. When the lead is close to the coil, the high frequency part of the spectrum curve moves in the direction of decreasing attenuation, and the curve moves up.

Six, the axial buckle

Axial distortion is under the action of electric force, the coil to both ends of the top, in the end of the compression, forced from the middle deformation, if the original transformer assembly gap is large or there is a forced displacement of the support, the coil in the axial twist into an S shape; This deformation changes only part of the capacitance between cakes and part of the capacitance to ground because the two ends are unchanged. The capacitance between the plates and the capacitance to the ground will decrease, so the resonant peak in the spectrum curve will move to the high frequency direction, the resonant peak near the low frequency will decrease slightly, the resonant peak near the middle frequency will increase slightly, and the spectrum line of 3ookHz~5ookHz basically keeps the original trend.

Seven, coil amplitude (diameter) deformation

Under the action of electrodynamic force, the inner coil generally shrinks inward. Due to the limitation of the inner support bar, the coil may undergo amplitude deformation, and its edge will be zigzag. This deformation will reduce the inductance slightly and change the capacitance to the ground slightly, so the resonant peak in the whole frequency range will move slightly in the direction of high frequency. The amplitude deformation of the outer coil is mainly outward expansion, and the total inductance of the deformed coil increases, but the distance between the inner and outer coils increases, and the capacitance of the wire cake to the ground decreases. So the first resonant peak and valley on the spectrum curve will move in the low frequency direction, and the following peaks and valleys will move slightly in the high frequency direction.