
7.5. Eddy Current Effects 85
The ability of a transformer to withstand these surge voltages is
described by the basic insulation level (BIL), the peak voltage of a
standard test pulse with a rise time to peak value of 1.2 µs and then a
decay to half value in 50 µs. BIL voltages and sine wave test voltages
are standardized for various voltage classes and types of transformers.
These values are shown in IEEE C57.12.00 for oil-filled transformers
and C57.12.51 for dry types.
7.5. Eddy Current Effects
Parasitic eddy currents in the windings and core can have a major
effect on transformer losses, especially in high-current transformers
and those with nonlinear ...