The solutions to common faults of dry-type test transformers are as follows:

(1) The insulation resistance of the iron core to the ground is zero

The resistance is zero, indicating that the real connection between the metals (may be burrs, wires, etc.) is brought to the core by paint, and the two ends between the core and the clip overlap; the insulation of the bottom leg is damaged, and the core and the bottom leg are connected; the metal falls Into the low-voltage coil, causing the drawing board to be connected to the core;). Solution: Use lead wire to push down the channel between the core wires of the low-voltage coil. After confirming that there is no foreign matter, check the sole insulation. If it still cannot be solved. The ground terminal of the welding equipment is connected to the grounding piece, and the welding rod is clicked on the bottom (current about 250 A). This problem can be solved with just one click.

(2) The travel switch fails or moves abnormally

The stroke switch is a device that protects the operator during normal operation of the transformer, such as a transformer valve. When any shell door is opened, the contact of the stroke switch should be closed immediately so that the alarm circuit is connected to the alarm.

(3) Common faults in the operation of the thermostat

During temperature control operation, there may be phenomena such as no over temperature alarm (or no over temperature alarm), no over temperature trip (or no trip over trip temperature), etc. At this time, it is necessary to check the thermostat setting after the transformer stops running. The accuracy of the fixed temperature value and the accurate placement of the temperature measuring element. If the temperature controller is not accurate, the set value of the temperature controller will be readjusted and the temperature measuring element of the temperature controller will be replaced.

(4) Reduce the insulation resistance of the iron core to the ground

This phenomenon is usually caused by humidity. After the insulation material is wet, the insulation resistance will decrease; the solution: place the iodine tungsten lamp under the low-voltage coil and continue to bake it for 12 hours. As long as the damp insulation resistance of the iron core and high and low voltage coils is low, the insulation resistance value will increase accordingly.

(5) There is discharge sound in the power frequency withstand voltage test

There are several possibilities: the tension plate is placed on the tightening part of the wire clamp to discharge, where the bracket can be used to make the tension plate and the wire clamp conduction well, which can solve the problem; the gasket, especially the crawling of high-voltage products (35kv), produces this phenomenon. Strengthen the insulation of the gasket; the virtual connection between the high-voltage cable and the connection point, or the angle with the splicing board. When the insulation distance of the connecting pipe is short, a discharge sound will also be produced. Increase the insulation distance and tighten the bolts again to solve the problem. Check whether there are dust particles on the inner wall of the high voltage coil. Because the particles absorb moisture, the insulating layer may be lowered, resulting in discharge.

(6) When power is transmitted, the shell is discharged from the subway slab

The results show that the conductivity between the shell (aluminum alloy) plates is not good enough, which is poor grounding. Method: Use a 2500 mΩ vibrator to destroy the insulation of the board or scrape off the paint film at each connection part of the shell, and connect the ground with a copper wire.

(7) The corner connection pipe is burnt out

Carefully check the blackened part of the high-voltage coil of the dry-type high-voltage test transformer, and scrape off the blackened part with a knife or iron sheet. If the carbon black is removed and the red paint is missing, it means that the internal insulation of the coil is not damaged and the coil is basically good. Determine whether the coil is short-circuited by measuring the rate of change. If the rate of change is normal, the fault is caused by an external short circuit, and the angle nozzle is burned out.