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Historical Review Of The Development Of Conducting System Winding
- Nov 07, 2017 -

The earliest production of distribution transformers are electrolytic copper as the conductive material of the winding system, of course, also useful as a winding wire aluminum material. In the hot-rolled silicon steel core, because the saturation magnetic density is low, the number of windings will be more, the wire used is longer, the circuit resistance is larger, the only way to maintain a low density, so hot-rolled Silicon steel core distribution transformer not only high load loss, load loss is also high. Cold-rolled silicon steel core, the core due to the high saturation flux density, the number of windings can be less, so that cold-rolled silicon steel core transformer distribution transformer losses can be reduced accordingly, the load loss will drop. Reasonable design of amorphous iron core distribution transformers, such as the use of a low-voltage high-voltage low-voltage double concentric winding arrangement, the use of foil winding windings, while reducing the loss of void cuts at the same time, it can reduce the load loss.

Distribution transformers in China's development history, have used aluminum wire, though to meet the performance requirements, but due to the low conductivity of aluminum, with the same capacity distribution transformers also use more aluminum, the corresponding larger load loss , Bulky, high weight; domestic users are not welcome to use aluminum transformers, the current production plant has not produced aluminum transformers.

In order to reduce the load loss, from the material, at present, China has extensive use of oxygen-free copper wire; In addition to flat wire, round wire, but also the use of copper foil. Because of the low resistivity of oxygen-free copper, the surface is bright, so the load loss can be low.

Winding structure development, pay attention to the improvement of thermal performance, try to use longitudinal heat dissipation oil gap, while the winding of the fastening structure to ensure that the short-circuit current generated by mechanical ability to withstand, that is to improve the transformer anti-export short circuit capability. In the amorphous iron core transformer, its structure is different, the winding is not supported on the amorphous iron core, with a separate winding clamping structure, combined with windings for the double concentric structure, making short-circuit mechanical force is not large, And short-circuit mechanical capacity to withstand high. In the six years from 1994 to 1999, more than 350 low-loss, low-noise distribution transformers produced by more than 350 distribution transformer manufacturing plants passed the short-circuit withstand test smoothly. These distribution transformers include oil-immersed, epoxy-cast insulation; silicon steel core, there are amorphous iron core; with winding wire, there are also copper foil winding.