From a D-I-Y vantage point, usenet newsgroups rec.crafts.metalworking and rec.woodworking address the subject periodically in motor FAQs.
Because the output of virtually all converters is 3-wire, there is no wyepoint neutral to connect to or measure, so no 120°-wye service. They are closer to a 240V Δ system, or maybe 240/120V 3ø 4-wire open-Δ. This gives you the “original” 240V—L1 and L2, and a second approximately 240V that is shifted by roughly 60° for L1-L3; giving around 240V for L3-L1. Don’t expect very tight voltage balance—that is generally implied when reading converter-manufacturer literature.
Because converter phase-to-phase voltage can be fairly unbalanced, so significant motor-horsepower derating [about 57% in some cases] may be necessary. Rotary phase converters have to be started and up to speed before running any connected 3ø motors. Don’t plan on powering any controls from the phase converter—they are not generally stable/regulated enough for that.
Don’t forget NEC ARTICLE 455.
Re: Phase converters#128294 01/14/0301:48 AM01/14/0301:48 AM
In a nutshell, it's like a UPS with 3 Phase output (per "Static" Converters). The 1 Phase AC may simply have a 3rd line created, or the entire AC is converted to a 3 Ø system. Either way, AC is converted to DC, which is then Inverted to AC.
If this was a Rotary Converter, it would be a 1 Phase Motor driving a 3 Phase Genny (Generator).
Better explainations may be done by others, or if I get proper data, I'll post it.
p.s. pay no attention to the following text. Just trying out some extended characters.
The method used in your explaination and on the converter shown on linked image is typical of the first type I mentioned in the first reply (creates a 3rd line).
The Motor(s) and the Converter will be connected to the 1 Phase power system, across the Ungrounded Conductors (or L-L). The Converter creates a circuit which has a Potential Difference between the newly created "Phase Line", and both of the existing 1 Phase Ungrounded Conductors.
The offset is probably in the range of 60º or so, which will be sufficent to create a Rotating Magnetic Field within the Motor.
This is the simplest method of creating Polyphase from Single Phase, but it is also the "Crudest".
Scott " 35 " Thompson Just Say NO To Green Eggs And Ham!
Steve, instead of visualizing it as a wye case, consider it more like a 4-wire-delta arrangement. There will still be ~240V between L1-L2 [and about ~120V L1-N and L2-N.] For the “manufactured” T3, there will be ROUGHLY 240V L1-T3, T3-L2 and ROUGHLY 208V T3-N, but don’t expect nice, even, symmetrical measurements like you’d see with conventional utility-type delta transformer service.
Also, don’t plan to power controls or other 1ø devices from T3 and any other lead. Voltage stability will be marginal (and likely disappointing) at best.
[This message has been edited by Bjarney (edited 01-25-2003).]