117 volt 3 phase????

I just picked up a new (to me) sinker edm, on the plate of the power supply it is stamped "117 volts" "3 phase". It has a three prong plug already on it, from the factory: one ground, 2 hots (10-3 so cord).
I am thinking that someone made a mistake on the plate, I have never heard of 117 volt 3 phase, and I have no idea how you could get that into a power supply with only 2 hot wires. Seems like it should be 240 volt to me. Am I missing something?

Wired Y, it would be fine on 208..............

I figured it out, it is just regular old single phase 120V. The schematic and stamp both read 3 phase, but 2 places in the documantation read single phase. I think the manufacturer offered a 3 phase booster, and sent out the wrong schematic and stamp for the model i have (no booster option).

Anyway, I hooked it up 120V, it works fine.

117 volts was the average utility voltage immediately post-WW-II, and most devices were UL Listed for that voltage, not withstanding the facts that some utilities were 110 or 115 and some were 120 or 125.

Utility voltages have crept upwards, and 127.5 was the voltage here, before the Great California Power Crisis (Enron, etcetera).

So, the power is nominally 120/240, but could be 125/250 or 117.5/235.

3 phase 115v

Just as a curiosity,
I have a GE motor (2hp 900 rpm 115 v 3 phase) from about the turn of the century,It weighs about 270 pounds and setup with a potential relay and start and balance capacitors runs very quietly whilst drawing 11+ amps under load , Carl in Edes Falls

I suppose at one point 115 three-phase was a common voltage.

But, just as residential voltages changed to 230 after WW-II, and this became mandatory with the 1950 NEC, with an exception for an "all gas residence" (we still have one or two of those on my block ... 40 amp services, but all appliances are natural gas), industrial voltages changed, too, with these going to 460 ∆ and still later 277/480 Y, and also 600 ∆.

At the electric utility where I was an EE many decades ago, we supplied our largest customers with 34.5 kV, with "customer stations" as large as 1 MVA (1000 KVA).

Some customers demanded 4160, which was a Y system, and we always used a ∆ system from 4800 to 500000, so if a customer wanted something unusual, like 4160, then he had to provide the transformer and its vault, at his expense, but we would provide the primary side to his equipment.

I can only imagine that 115 three-phase was a pre-WW-II voltage.

However, I recently encountered a current production motor which was 115 three-phase, but it was a special purpose motor, perhaps one which was intended as a "component" within a larger system.