Phase perfect

[Eddyde]

Yes, 240v to ground or there about is what I think he said he has, but even if it is 208v, it would still be too high for the electronics that need only 120v when referenced to ground/neutral. I guess his gripe is, it's still not the same as the 3 phase power that comes from the grid.

When I hooked up my CNC panel saw many years ago, it noted a specific terminal for the stinger phase, if present. My friends machine did not provide that Information, so he had to trace the circuit from the step-down transformer back to the power terminals to ensure it was connected to the mains and not the generated phase.

He also complained about the high-pitched whine.

 

[Beckerkumm]

The high leg is to be avoided with controls or transformers whether a PP or an RPC generates it. Utility three phase where all three legs measure 120v to ground becomes 208v three phase. 240 Delta three phase will have a high leg. The PP balances that 208v leg to the other two utility generated legs so any two legs create the same voltage. An RPC will have legs that when combined, might produce different voltages on any two legs, ie 235,240,245 etc when measured at the motor. Some RPC also can balance any two legs closely and be used with CNC but the same issues still exist.

Dave

 

[borges1]

Im unfamiliar with stinger phase too, and not an electrician. But i did wire all my own 3ph and have spent the time to get it working correctly and to code on my shop, so my terminology may be off.

My original RPC was an old used one and generated voltage variances within legs. When i bought some brand new machines with more advance electronics i ended up having to replace the RPC with a brand new voltage stabilized version RPC so i would avoid frying the electronics. It uses capacitors and some wizardry beyond me as i recall - not straight 3ph off the motor. The static converters were beyond my budget at the time. I always thought PP avoided this problem and were more efficient converters. There will always be different voltages between different legs depending on the version of converter (220, 480 etc) but that is intentional and to be expected. You need to make sure you have the leg voltages correct to the mahcine, and for more advance machines the delta pattern correct. For instance my big table saw only runs on 3ph from my RPC, but the display uses the 120 leg in that system to run the display 100% of the time it is plugged in and the 3ph breaker is on. If you get the high legs wrong (incorrect delta pattern) the motor runs backward when you turn it on - thats in the manual. I assume for my shaper the rotarary switch that reverses the motor is actually just switching which high leg goes where.

My understanding is that the issue is the voltage variance within each leg of system produced by the most basic RPCs is a problem for touchy electronics.

Edit: i did't seen Beckerkumm's post. he said it more succinctly.

 

[Beckerkumm]

Reversing any leg will reverse the motor. The high leg creates the 240v delta system and mucks up any controls or electronics needing 120v legs or a transformer( as stated earlier ). The PP should balance the voltage between legs. My PP all measure within 1 volt between any leg on any sized machine, from 30 hp to 1 hp. Maintaining similar voltage across the legs over a wide range of amperage is what becomes difficult. Old RPC often specified a minimum hp as well as a max due to the inability to balance over a range of loads. the newer electronic ones are much better but I don't believe they will balance within 2% as PP guarantees.

Dave