It states "The leakage current is the lowest 10uA or less for the most stringent applications."
Does anyone know what that means ?
yeah.
normally, when a transformer is designed the intention is to keep the magnetic flux in the primary confined strictly to the windings of the primary. Similarly, the intention is to keep the magnetic flux confined to the sec windings only. But this is impossible to do in a practical transformer because the whole theory of operation of a transformer is coupling of magnetic flux between pri & sec to transfer power to the output. SO, there is bound to be some primary winding flux leaking into the sec winding. As a result there will be some leakage current associated with this. In an isolation transformer leakage is bad as the main function of this sort of transformer is isolation. That's the attribute that's being touted & sold for a premium. So, lower the leakage current, the better the isolation between pri & sec.