Detailed explanation about transformer model with ＂B＂

The B in SB11 and SCB10 all means that the low-voltage winding is foil-wound, and it only refers to the low-voltage winding, because the high-voltage winding needs to have a tap, which is the gear position, so the B here only refers to the low-voltage coil, and the high voltage is still wire-wound. . In addition, if the capacity is too large, foil winding cannot be used for low voltage. Because the current is too high, the copper foil or aluminum foil cannot be too thick. When it reaches a certain thickness, it will be too hard. The metal will have stress, which is the force to maintain the original shape. When winding, it is necessary to When wound into a circle or oval, the copper foil will expand in the direction of its original shape. The thicker the copper foil, the more difficult it is to wind, and at the same time the greater the internal stress. After a certain level, low voltage can only be wound with wire.

There is another situation, such as rectifier dry transformers, and phase-shifted rectifier dry transformers made by Yuguang. Low voltage can only be wire-wound, because it requires many, many taps. Copper foil cannot tap, and there are many such taps. Generally, the high-voltage coil is inside and the low-voltage coil is outside. It is the opposite of our common transformers, because the low voltage comes out a lot and needs to go out of the transformer coil. If the low-voltage coil is placed inside, then the many outbursts are If it cannot be taken out, this will also make it much more expensive than a conventional transformer arrangement in which the high voltage is outside and the low voltage is inside.

For example, for common oil transformers, 630KVA is generally the limit. Those with a capacity above are wire-wound, and those below can be wire-wound or foil-wound. For dry transformers, 1250-1600 is the limit. If the capacity is large, the copper foil is very thick, and the winding The thread machine cannot be wound. For the same capacity and voltage, the cost of foil winding is generally lower, and that of wire winding is more expensive. In fact, it is easy to understand that copper foil has no insulation layer, and the insulation only relies on the insulation between each turn, while wire winding of the same cross-sectional area , each wire must have an insulating layer, which will increase the overall insulation, which will lead to a large volume of the entire coil. The high-voltage coil is outside, which will also cause the length of each layer of the high-voltage coil to become longer, which will also lead to the distance between phases. becomes larger, which will also cause the iron core to become larger. This is an interrelated relationship.