The so-called micro-transformer is the power industry equipment, mainly includes two categories, one belongs to the micro-current transformer, the other is the miniature voltage transformer. Micro-transformers are usually used in a variety of power instruments for measurement and protection purposes.
Compared with ordinary transformers, the main special thing is that the size is small and the precision is higher. No matter what type of micro-transformer it is, it should meet certain performance requirements, so do you know what is mainly included?
The first is the insulation requirements, wherein the insulation requirements between one and two windings for fixed primary winding and two windings between the rated operating frequency tolerance voltage is 3kV (square mean root value), when the specified insulation requirements according to the Ⅱ protection insulation requirements, the frequency tolerance voltage is 4kV (square mean root value). At the same time, the insulation requirements between two primary windings and two windings of miniature Transformers are: the rated frequency tolerance voltage between the primary windings is 3kV (square mean root value), and when the specified insulation requirement is Ⅱ protection insulation, the frequency tolerance voltage is 4kV (square mean root value).
In addition, the frequency tolerance voltage between a winding and two windings is 3kV (square mean root value), and when the specified insulation requirement is Ⅱ protection insulation, the frequency tolerance voltage is 4kV (square mean root value). It is also necessary to pay attention to the requirements of insulation resistance between miniature transformer windings, which usually require that the insulation resistance between one and two windings must not be less than 1G at 500V DC voltage.
At the same time also to meet the requirements of its overload capacity, that is, under the rated load, the transformer after 5.5 of the test, the transformer is still intact, when returning to the rated current work, the transformer error does not exceed the specified error limit of 1.3 times times, after demagnetization, the transformer to meet the original accuracy level requirements. In addition, the requirements of its temperature rise influence should also be taken into account. At an ambient temperature of 40 ℃, the surface temperature rise of the miniature transformer does not exceed 25K at the IMAX current. And at the upper and lower limit temperatures, the miniature transformer still meets its accuracy level requirements.