Hi
I have a rotary converter that turns single phase into three phase. The motor on the converter says it is 5 hp. How can I tell what size 3 phase motor it will run
Thanks

Best to consult the manufactuer of your specific unit.

Here is a link to one of the more popular ones, look for Rotary Converter Sizing Chart link at the bottom.

3 Phase Converter Info- Sales- rotary phase converter, static 3 phase rotary converters. (http://www.phaseconverter.com/)

If this is not your manufacturer, Google "Rotary Phase Converter".

Thanks tk
I got the 5 hp converter used with a band saw I bought. It was used and has no manufacture named.
I looked at the site you recommended. Very informative.
Here is the rest of my question. Maybe I should have asked it from the start. I also have a planer that has a 7.5 hp 3 phase motor. Per the information I read, from the site, it says I need a 20 hp, 15kw converter for hard start applications. Does that sound right to you? It takes a 20 hp , 15 kw converter motor to run a 7.5 hp 3 phase motor? The cost of the converter is $1495, I can buy a single phase 7.5 hp motor for $5-600 dollars. As I read the info it would be 1/3-1/2 the price just to replace the 3 phase with a single phase.

See if there is a code letter on the nameplate. Motors can draw 300-600% of their rating upon starting. See: motorsanddrives.com - Locked Rotor Code Letters (http://www.motorsanddrives.com/cowern/motorterms6.html)

Taking 7.5 HP * 746 W/HP =~ 5,6 KVA (some conversions thrown in)

15 KVA / 5.6 is about 2.7 X, so it's a reasonable assumption.

Don't forget to consider the wiring requirements which includes capacity and breaker space and disconnects, labor and inspections in your calculations.