I purchased a 240/480 to 120/240 distribution transformer, hoping it would serve as a cheap yet robust isolation transformer when connected in reverse (of course raising the voltage to 240V). Several transformer manufacturers claim that these may be safely reverse connected, with only minor consequences (larger inrush currents and slight voltage drops).
However, when I measure the voltage with my digital multimeter from mains ground to the output, I measure voltages of 120V and 94V depending on which output wire I use. Does this indicate that the supply is actually unisolated? My transformer has a shielded ground plane in the middle of the core--this shouldn't make a difference in terms of isolation, correct? I get the same result when I leave the center plane floating.
As a comparison I measured the voltage between GND and a rewound microwave transformer that I knew was isolated--this measured around 20V.
I would really appreciate if anyone could explain where these voltages come from and if my distribution transformer setup is indeed providing isolated power.
However, when I measure the voltage with my digital multimeter from mains ground to the output, I measure voltages of 120V and 94V depending on which output wire I use. Does this indicate that the supply is actually unisolated? My transformer has a shielded ground plane in the middle of the core--this shouldn't make a difference in terms of isolation, correct? I get the same result when I leave the center plane floating.
As a comparison I measured the voltage between GND and a rewound microwave transformer that I knew was isolated--this measured around 20V.
I would really appreciate if anyone could explain where these voltages come from and if my distribution transformer setup is indeed providing isolated power.