What is the dry type transformer?
Dry-type transformers are widely used in local lighting, high-rise buildings, airports, terminal CNC machinery and equipment, etc. Simply speaking, dry-type transformers refer to transformers whose iron cores and windings are not immersed in insulating oil. Dry type transformer is mainly composed of an iron core composed of silicon steel sheets and a coil cast with epoxy resin. An insulating cylinder is placed between the high and low voltage coils to increase electrical insulation, and the coil is supported and restrained by a spacer loose performance. And the coil is supported and restrained by the spacer, and the fasteners overlapped by its parts have anti-loosening properties.
Dry-type transformers are generally suitable for power distribution, most of them have a capacity below 1600KVA and a voltage of 10KV. Some of them have a voltage level of 35KV.
What are the transformer windings?
Winding: high-voltage winding and low-voltage winding.
From the perspective of the relative positions of the high and low voltage windings, the high voltage can be divided into concentric and overlapping types.
The transformer winding refers to the circuit part of the transformer, which is made of enameled copper wire or enameled aluminum wire with high conductivity and is used in the power system. The winding should have sufficient dielectric strength, mechanical strength and heat resistance.
Windings are usually divided into two types: layer type and pie type. The turns of the winding are arranged and wound continuously along its axial direction, which is called a layered winding. Generally, each layer of the layered winding is cylindrical, so the winding composed of two layers is called double-layer cylindrical type; the winding composed of multiple layers is called multi-layer cylindrical type.
Enameled Wire Used For Transfomer Windings coils
The conducting material used for the winding depends upon the application. Small power transformers are wound with solid copper wire, insulated usually with enamel. Larger power transformers may be wound with wire, copper, or aluminum rectangular conductors. Strip conductors are used for very heavy currents. Large power transformers use multiple-stranded conductors as well, since even at low power frequencies non-uniform distribution of current would otherwise exist in high-current windings. Each strand is insulated from the other, and the strands are arranged so that at certain points in the winding, or throughout the whole winding, each portion occupies different relative positions in the complete conductor. This “transposition” equalizes the current flowing in each strand of the conductor, and reduces eddy current losses in the winding itself. The stranded conductor is also more flexible than a solid conductor of similar size is. Windings on both the primary and secondary of power transformers may have external connections (called taps) to intermediate points on the winding to allow adjustment of the voltage ratio. Taps may be connected to an automatic, on-load tap changer type of switchgear for voltage regulation of distribution circuits.
Transformer Manufacturers
1. ABB (formerly ASEA Brown Boveri) is one of the top transformer manufacturers, offering liquid-filled and dry-type transformers and full life cycle support including replacement parts and assemblies.
2. Schneider Electric manufactures general purpose, industrial control, dry, liquid, low voltage, instrumentation, and three- and single-phase transformers.
3. Jiangsu Huapeng Transformer Co., Ltd. is the largest transformer manufacturer in China. Production of three-phase, pole-top, oil-immersed, dry-type transformers. The company focuses on the production of transformers with rated power up to 750kV and 1000MVA.
4. TBEA in Changji, China, TBEA is one of the oldest transformer manufacturers in China. The company manufactures and distributes a range of equipment including transformers, cables, wires and high voltage switches.
5. Toshiba was founded in 1875 by Hisashi Tanaka, headquartered at No. 1-1, Shibaura 1-chome, Minato-ku, Tokyo, Japan. Toshiba offers transformers with power ratings between 69 kV and 765 kV, from 100 MVA to 800 MVA and 1,100+ MVA, available for custom orders.
6. Siemens is a German multinational company with annual revenues in excess of $90 billion and a leading European manufacturer of transformers. The company offers a range of transformers, including HVDC (High Voltage Direct Current) transformers, phase shifting transformers, power transformers and industrial transformers, among others.
