Voltage transformer insulation structure, aging factors and corresponding measures
In transformer design, the insulating portion is generally the traditional design method, namely the method of using the test statistic to determine the life of the transformer insulation. In recent years, the transformer insulation design method modern design methods, such as finite element analysis, reliability design technology and optimization of design technology, and with the development of computer technology, the use of large-scale professional analysis and optimization software for the analysis and design, and the use of modern program design method than using traditional design methods to design programs more economically reasonable. Modern design approach is still in the evolving modern design method is difficult to determine the specific content, but currently has a variety of more mature way to sum it up: optimal design, finite element analysis, reliability analysis, design, value engineering design expert system; computer-aided design. Cross use these methods, can constitute a variety of unique application objects, such as reliability optimization design.
A voltage transformer insulation structure
Voltage transformer insulating medium is divided into dry, pouring oil-immersed and gas four categories, voltage transformer insulation structure according to the voltage level of the different environment take a different approach. Usually designed for the measurement of low voltage transformer is a dry, high-voltage or ultra-high pressure sealed gas insulation (such as sulfur hexafluoride) transformer, dry type. Guss applicable to 35kV and below voltage transformer products are more 35kV oil-immersed. Epoxy resin cast transformer compared with the traditional oil-immersed, inflatable transformer has no oil, no gas, no housing, and life-long maintenance-free, good insulation, etc., is commonly used in the world A transformer.
1, the dry insulation structure
Dry-insulated structure manufacturing simple, low-cost, but not high dielectric strength, so this structure generally does not exceed 380V voltage. Wire QZ type enamelled round copper wire, insulation material used in the insulation structure: insulating paper, glass cloth tape, Bakelite. With bakelite or plastic skeleton between the coil and the core insulation, interlayer insulation as well as a main insulation between the secondary coil, generally used the Huangla silk or polyester film. Instrument voltage transformer toroid core coil insulation, general insulation cardboard, and then around the two layers of glass ribbons, the Huangla silk or polyester film with. Dry-type structure is simple, but the larger, apply only to the low-voltage indoor device or instrument voltage transformer 10kv and below.
Pouring insulation structure
Called pouring type insulation is mixed with a certain proportion of resins, fillers, pigments, and curing agents, casting equipped with a transformer primary and secondary windings and other parts of the mold, the solid formed by curing the insulating . Curing the molded mixed glue both fixed the relevant parts, and the main transformer insulation. Pouring insulation has good insulation properties, high mechanical strength, moisture, fire, etc.. Resin glue mixture having a good fluidity at room temperature or elevated temperatures, and may be filled with a small gap, and easily cast into a relatively complicated shape, the resin glue mixture also has a strong adhesive action, can metals and many insulating material firmly ground bonding with the ideal transformer insulating molding material, widely used in indoor 35kV and below voltage transformer.
Epoxy resin commonly used in our transformers and two unsaturated resin. Unsaturated resin inexpensive, room temperature curing, the casting process is simple, but its electrical and mechanical strength is low, and poor heat resistance; addition, unsaturated resin saturated vapor pressure high the glue mixture appropriate vacuum degassing, when pouring and it is not vacuum bubbles pouring in vivo; unsaturated resin cure shrinkage, mixed-curing adhesive is easy to crack. Unsaturated resin is only applicable to low-voltage products. Epoxy curing shrinkage is small, the saturated vapor pressure, suitable for pouring, so that the better the flow of the glue mixture, under the high temperature, high vacuum can maximize degassing, thereby obtaining the ideal performance of the casting body.
Pouring insulation semi-pouring and pouring two: half Guss the coils individually cast, then fitted core; wholly Guss coil and core loaded with pouring. Epoxy full cast voltage transformer has the following characteristics: (1) to achieve a non-oil, protect the environment; (2) to achieve a maintenance-free, saving a lot of manpower and material resources and outage time; (3) manufacturing materials noncombustible or flame self-extinguishing material, fire-retardant, explosion-proof.
