How is Hi-Pot affected by a high value of interwinding capacitance?
A high value of inter winding capacitance may be associated with very close primary to secondary coupling and may also be an indication of high electrostatic coupling.
Interwinding capacitance is of special interest in medical applications where primary to secondary isolation is of special interest.
A high value of interwinding capacitance may therefore result in higher primary to secondary leakage current and lower Hi-Pot voltage threshold.
The Hi-Pot current level measured will be a function of frequency, current due to the capacitive element of Hi-Pot will increase with increasing frequency(Vapplied/(1 / 2 π f c). As frequency increases the capacitive reactance will decrease and the Hi-Pot current will increase. This should be taken into account when setting Hi-Pot limits.
In summary a high interwinding capacitance may result in lower levels of voltage breakdown between primary and secondary and this may lower Hi-Pot test levels.