Run 3 Phase DC Power Supply off Single Phase? - Page 1
Forum section: electronics / beginners

author: eprigge
author_rank: Newbie
timestamp: September 16, 2023, 12:43:54 pm
content: Hi,I have a 6KW 3-phase DC Power Supply (Xantrex XDC Series) and I'm wondering how much power I can get out of it if I run it off single phase 240V. It will start and operate off of single phase 240V, I have tested that. But I'm wondering how much power I can (safely) get out of it. I'm thinking 3KW, since that would be about the same current in the conductors as 6KW on three phases. I'm assuming that it has a 3-phase full wave rectifier feeding a cap bank so it would seem if I don't go over the rated current per leg I won't overload anything.Please let me know if you can think of any other issues!Thank you,Eric

author: Doctorandus_P
author_rank: Super Contributor
timestamp: September 16, 2023, 12:54:15 pm
content: The rectifier can either be separate diodes or an integrated rectifier bridge. And when all diodes are in a single package, then it's more about the dissipation of the total package. There still is of course a limitation to the current through each diode, but usually these diodes are a few sizes bigger then they need to be.The capacitors behind the bridge may be a bigger problem. They receive only a third of the charge pulses and will have a much bigger ripple current.Another possibility could be to re-create the third leg with some phase shift network.

author: BrokenYugo
author_rank: Super Contributor
timestamp: September 16, 2023, 01:12:30 pm
content: I know the derating for 3 phase VFDs on single phase is usually quoted at 60%, very similar problem with the 3ph rectifier/filter stage being undersized for single phase, 3KW out of 6 is probably a safe enough guess to test it.

author: eprigge
author_rank: Newbie
timestamp: September 16, 2023, 02:26:47 pm
content: Thanks for the confirmation guys. I do have a rotary converter for generating 3-phase power but the power supply doesn't like it. I think it's because the manufactured leg (T3) is designed to be a little high (in this case ~250V) and that might be a little too much for the PSU (it gives an error, bad power). Its input is rated for 190 to 242V.Anyway, thanks for the help!Eric

author: CaptDon
author_rank: Super Contributor
timestamp: September 16, 2023, 07:56:57 pm
content: Those rotary 3-phase converters were really designed to run 3-phase motors where there is some lead/lag current interaction between the motor and the converter. We had a 20KW FM transmitter on a mountain top where only single phase was available and the rotary converter looked more like line A and B being 180 degrees out of phase and the phantom leg being 90 degrees out of phase. It looked horrible but being that the transmitter was wired in a Y configuration and each phase to neutral had a correct 240vac on it and supposing the high voltage rectifiers were also wired in Y configuration it seemed to work o.k. All motors for blowers were single phase rotrons as were the control transformers for low voltage supplies and filament power. One thing for sure, the phase to phase voltage was whacko!!! Rotary converters were really nearly a 'must' for machine shops in the country rural setting where single phase was all they had. Here at home my whole street is fed by a single 4KV line and we typically have 5 houses per transformer each marked as 25KVA. As poor as that sounds our power quality is actually pretty good (When is isn't shorted out by a fallen tree or tree limb!!! Here's the really weird part, I can see where the 4KV feeder crosses the main road to feed our side road however I don't see any sort of return?? It almost seems our earth grounds at our homes provide the return. There isn't even the protective 'lightning catcher' ground wire above the 4KV line!!

author: kb1
author_rank: Newbie
timestamp: December 03, 2024, 11:43:34 pm
content: Quote from: eprigge on September 16, 2023, 02:26:47 pmWere you ever able to find a working solution to powering the XDC from a single phase supply?Kris