High Voltage Power Supplies & Safety Information

Can I Operate a high voltage power supply designed for 220Vac, single phase from a 208Vac, three phase electrical service?

The simple answer is yes, if you connect any two phases of the 208Vac electrical service to the two AC input wires (solid brown and solid blue) you can operate the power supply. Connect the green/yellow wire to ground and ground the power supply properly along with making the required load return connections. But this simple answer needs some qualification.

220Vac, single phase has a typical tolerance of ±10%, so that means the low end could go to 200Vac. 208Vac, three phase also has a typical tolerance of ±10%, that means the low end could go to 187Vac. This is 13 volts lower than the "low end" of 220Vac, which is 200Vac. So it is possible that if using 208Vac to power a unit designed for 220Vac the input line could fall lower than the specified input voltage.

Is this a problem? It could be, but it’s possible it will not be an issue. The only time this situation could be problematic would be if the unit is being used at maximum voltage/maximum current…providing maximum power. Then if the input voltage falls below the 200Vac level the unit could possibly “drop out of regulation” creating a Regulation Error fault. The power supply will stop generating high voltage, it will not be damaged but this shut down could present process interruptions. If you are not using the power supply at maximum voltage/maximum current and maximum power than most likely the power supply will not create this fault condition.