IEC 60076-14-2013 pdf free

IEC 60076-14-2013 pdf free.Power transformers – Part 14: Liquid-immersed power transformers using high-temperature insulatio materials.
Since ageing and lifetime of the insulation system so strongly depend on the temperature, combinations of insulating materials with different thermal capabilities are used within a unit in order to optimise the thermal and economical design of the transformer. In order to simplify and standardize, three distinct insulation systems are defined, based on the degree of high- temperature insulation content. The conventional insulation system is the basis for reference and contains no high-temperature insulation. This system is used as a reference only in this document.
Although a winding with radial spacers, typical for a core-type power transformer is used to illustrate the various insulation systems, the application is not limited to this type of transformer. Each of the insulation systems described is an illustration of the definition and the description is applicable to any other type of transformer with different types of windings, such as layer-type and shell-type pancake windings.
4.2 Winding insulation types
4.2.1 General
The transformer winding insulation is a component of the insulation system. Subclauses 4.2.3 to 4.2.4 illustrate different low voltage (LV) and high voltage (HV) winding types with examples based on power transformers, which have a high degree of winding separation. Table 2 summarizes and compares the different variations.
The barrier insulation between the individual windings shall be treated as a separate entity when properly designed cooling channels separate the material from the winding itself. In this case, the liquid circulation provides sufficient cooling to avoid exceeding the thermal capability of the barrier insulation. If the barrier insulation touches the winding then it shall be considered part of that winding. This is especially important for layer type windings when the layer insulation touches the winding conductor. In this application, the layer insulation shall be treated in the same manner as the winding conductor insulation.
Sufficient testing shall be performed to verify the thermal profile. This shall be accomplished by actual thermal measurement of critical locations taken during prototype and unit testing. Once thermally mapped, materials shall be selected appropriate to the temperature requirements of the specific location. Supporting test data sufficient to validate the manufacturer’s thermal model shall be available upon request as part of the type testing.
NOTE The different insulation systems can be explained by considering the transformer as an assembly of individual isolated windings, separated by insulation barriers and cooling channels. A series of winding types could then be used to illustrate how parts of different insulation systems can be combined in a single transformer. In some cases it might not be necessary to use high-temperature insulation in the same way for all windings.IEC 60076-14 pdf download.