We all know that the safe and fast operation of transformers is an important indicator of a product. So how to analyze the transformer failure? Today we will talk about the seven elements of the transformer fault operation check.
1, the winding method is loose, transposed improper handling, too thin, the formation of a magnet suspended. Engaged in damage to the end of the point of view, the deformation of more common place, especially the transposition wire transposition.
2. At present, the accounting sequence of each manufacturer is based on the idealized model of uniform distribution of the leakage magnetic field, the same diameter of the turn, and the equal phase force. In fact, the leakage magnetic field of the transformer is not uniformly distributed. The relative convergence of the partial convergence of the iron yoke, the region of the magnet wire is subjected to greater mechanical force; transposed wire in the transposition due to climbing will change the direction of the transmission of force, and the onset of torque; pad modulus of elasticity, Axial pad is not equidistant spread, alternating magnetic leakage will make the occurrence of alternating force delayed resonance, which is why the core yoke, transposition Department, with the pressure tap the corresponding parts of the main line cake The root cause of deformation.
3, the winding pre-tightening control improper formation of the ordinary wire transposition wire displacement of each other.
4, anti-short circuit can not account for the temperature calculation of the electromagnetic bending and tensile strength of the impact. According to the normal temperature, the short-circuit resistance can not reflect the actual operating conditions. According to the experimental results, the temperature of the magnet wire has a great effect on its yield limit of 0.2. With the progress of the temperature of the magnet wire, the bending resistance, tensile strength and elongation As a result, the flexural tensile strength at 250 ° C is higher than at 50 ° C and the elongation is decreased by 40%. The practice of transformers, the additional load, the average winding temperature up to 105 ℃, the hottest temperature up to 118 ℃. Ordinary transformer operation reclosing process, because if the short-circuit point a moment can not be seen, it will be in a very short period of time (0.8s) followed by a second short-circuit impact, but due to the first short-circuit current impact , Winding temperature rises sharply, according to the GBl094 rules, the maximum should be 250 ℃, then the winding resistance to short-circuit has dropped substantially, which is why the transformer short-circuit after the reclosing most of the episodes.
5, the choice of soft wire, but also to form a transformer short-circuit to poor one of the main reasons. Due to the early lack of experience with this, or winding equipment and process difficulties, manufacturers are reluctant to use semi-hard wire, portrayed when there is no such request, from the failure of the transformer are soft wire.
6, frequent external short-circuit events, multiple short-circuit current impact after the accumulation of electrodynamic force caused by electromagnetic wire softening or internal relative displacement, resulting in insulation breakdown.
7, the winding turns or wires uncured between the anti-short circuit to poor. No damage was done to the windings that had been impregnated in the early stages.
Regardless of any one product, there will always be one way or another, so we should find a way to deal with it.
