Before making our dry-type transformer, we need to design it. When confirming the transformer design, we need to pay attention to the winding and insulation. First, confirm whether the drawing is consistent with the production product, and then check the wire gauge after confirming that its capacity is correct. After finding the wire gauge, confirm the number of turns. Secondly, confirm the wiring mode. The high-voltage drawing shall be based on the tap out, the number of turns of the tap out, and the low-voltage drawing shall be based on the winding mode, the length of the tap out, the transposition position, the internal and external diameters of the windings, the amplitude, etc. Next, calculate the length and width of the paper cylinder and cardboard according to the inner diameter of the coil, and then find out the end insulation length drawing from the drawing number, including the thickness of the oil duct cushion block and corrugated paper oil duct, and then find out the end ring and upper and lower yoke insulation in turn.
The second part is the starting side winding and insulation. Check the drawing to confirm the length of the outlet. If it is spiral type, different scales are required. The length of one more conductor is measured for the latter group than for the former group, so as to keep the outlet neat and beautiful. After the head is bent, a layer of corrugated paper shall be wrapped in half folds. The head shall have the same radian angle. After the head is sorted out, the corrugated paper shall be wrapped with a thickness of 3mm, and the external white cloth belt shall be used for binding (the tightening belt is not used, and it is easy to burn out during welding).
Before winding the paper drum, measure the outer diameter of the mold with a caliper, and cut the cardboard that needs to be padded. It is better to select one millimeter for the paper cylinder cardboard to be lapped at both ends and wound tightly with the tightening belt. During the winding, the assistant worker should use a hammer to knock tightly along the tightening belt.
When the cylindrical winding end insulation is made of paper strips, the straight cloth tape is used to bind it on the first turn of wire and start winding the first turn. The cloth tape (tightening tape) is tightened around the circumference under the wire turn while winding. The end insulation shall be bound in figure 8. Tighten the cloth tape to bind the first turn and the end insulation together. Turn the cloth tape up when winding the second turn, and press it down when winding the third turn, so as to tighten the end coil in a zigzag way. The cylinder winding shall be transposed once in the middle. After transposition, a layer of corrugated paper shall be wrapped and a half millimeter cardboard pad shall be placed inside and bound with white cloth tape. During winding, the auxiliary workers shall keep close and control the amplitude direction. 0.08mm cable paper shall be used for three layers of insulation between layers, and the second turn shall be connected with the outlet
A half millimeter cardboard shall be used for separation to avoid damaging the insulation. Also, the scissors shall be added at the bottom layer.
At the end, the two outlets should be aligned. Similarly, the outlet and the penultimate turn should be separated by cardboard, and the two outlets should be fastened. The whole coil shall be fastened with a tightening belt before wire cutting.
The spiral winding is mainly a low-voltage winding above 630 KVA, and the outlet is the same as the cylindrical winding. It should be noted that the bent part of the outlet is compressed with a diagonal tension belt as the front tension cloth belt until the end of the outlet and tied to prevent the outlet from popping out and coil tension.
Third, semi-finished coil insulation test. After and during the winding of low-voltage coil, use a multimeter to measure the insulation, mainly to measure whether there is short circuit between turns.
Fourth, lead tin pre assembly and welding.
1. Lead preparation
Where there is a part drawing, the parts shall be processed according to the specified process route.
Blanking shall be carried out according to the drawing size and actual size, such as cable wires, thin round copper, etc., and welding preparations shall be made, such as flattening of copper round welding parts, wire binding, flattening and pre welding of cable wire welding parts penetrating copper phosphorus, etc.
Wrapping: Any lead wire or a section of the lead wire that can be wrapped in advance.
Pre welding: the rule is the same as that of wrapping paper. Welding on the machine body shall be reduced as much as possible, and preparations before and after welding shall be made.
2. Lead wire welding;
Heat the weldment. When the weldment is dark red, start to add copper phosphorus electrode. With the increase of temperature, the fluidity of copper phosphorus electrode is accelerated, and it can quickly penetrate into the gaps. The weldment will show bright red. Stop heating when the copper phosphorus electrode is saturated, and add water to cool it when the red disappears.
3. Lead overall assembly, welding and insulation binding
The half lapping method shall be adopted for the wrapped insulation of the configured lead wires, that is, the lapping length of the first and second laps shall be 1/2 of the width of the corrugated paper. This can ensure that the insulation thickness is consistent everywhere. When binding, the damaged
Clean the insulation and then wrap it up. The burnt insulation may be short circuited. Clean the surface of the copper bar before welding the copper bar. After welding, cover the body with paper to prevent copper slag from falling into the coil and affecting the insulation.
Fifth, labeling. The label shall indicate the work number of the coil high and low voltage winding personnel, indicating the time, coil capacity, model, high and low voltage wire gauge and number of coils. High voltage also has a DC resistance value.
Sixth, coil package. During coil assembly, wrap the upper end of the iron core with half millimeter cardboard to avoid scratching the coil. When the coil falls, a person should pull the cardboard from the upper opening of the coil to prevent it from being carried down by the coil. If the coil amplitude is too large and the phase distance is too low, wax the coil or separate it with a cardboard (wax the cardboard).
Seventh, semi-finished product testing. The main purpose of semi-finished product testing is to see the insulation, transformation ratio and DC resistance.
Eighth, overall assembly. Lift the assembled core into the oil tank of the transformer body. When falling, align the bottom corner bolts and place them flat. Insert the bolts and press them evenly. Do not tighten them at once, but tighten them several times and evenly. The joint of the rubber rope shall be sealed with sealant, fixed with iron wire at the four corners of the body, and pulled out with pliers after other screws are fastened.
The above is a detailed explanation of the production process of the dry-type transformer, and I hope it will be helpful to everyone.
Post time: Oct-11-2022
