Generally, the number of turns of transformer turn-to-turn short circuit fault is very small. When the fault occurs, this part of the winding is short-circuited, but it is still a closed coil, which is equivalent to a new "short-circuit transformer" with high turns ratio NS. The remaining part without short circuit can be regarded as another transformer n 1'. The original transformer winding has become a winding composed of turn-to-turn short circuit winding and other windings in parallel.

Analysis from the perspective of short circuit turns. Considering the saturation factor of the transformer, the magnetic flux in the iron core will not change obviously even if the turn-to-turn short circuit occurs.

Assuming that the induced potential of the primary side is E 1, the induced potential of the short-circuit turn is ES=(NS/N 1)E 1, and the short-circuit turn impedance ZS=Z 1(NS/N 1)2 is very small, which will cause a large short-circuit current is =

This current provides a monitoring clue for turn-to-turn short circuit in transformer. The winding with turn-to-turn short circuit melted due to excessive current, and copper beads were found around it on site.

Extended data

Method of judging turn-to-turn fault:

(1) Measure the inductance. If the inductance is much smaller than the normal coil, there is a turn-to-turn short circuit.

(2) Measure the current. Connect an AC ammeter or multimeter in series with the coil to be measured and connect the rated AC voltage. If the current is much larger than the normal coil, turn-to-turn short circuit will occur.

(3) Series load. Connect an incandescent lamp with appropriate power to the tested coil string and turn on the power supply (pay attention to safety). If the bulb is much brighter than the normal coil, there will be turn-to-turn short circuit.