Converting DC plant amperage to AC amperage

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TDrake

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I have two DC plants rated at 8000 amps each. I believe they are rated at 48 volts. I would like to convert them to 480 volt DC. I have done this before but do not remember and I do not want to ask my boss. I didn't see a formula for this in the NEC. Any ideas?
 
TDrake said:
I have two DC plants rated at 8000 amps each. I believe they are rated at 48 volts. I would like to convert them to 480 volt DC. I have done this before but do not remember and I do not want to ask my boss. I didn't see a formula for this in the NEC. Any ideas?
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Do you really mean 480Vdc?
If so, ten times the volts, one tenth of the current.
 
I would assume that he is looking for 3 phase AC, not single phase AC, so you have to divide by the square root of 3.
 
TDrake said:
Sorry, I am trying to convert to 480 AC
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OK. I can do that.
But what is the circuit configuration?
I assume there's a transformer.
What is the secondary voltage?
How is it configured?
Hexaphase is common at low voltages.
Is the rectifier uncontrolled (diodes) or controlled (SCR)?

But some orders of magnitude:

C12273-twoLHSlimbs02-1_zps97ede7c5.jpg

It's 10,000A at 50V

Input is 400V at about 980A.
 
And just in case the OP is not following completely, to get AC at any voltage requires an inverter.
When you say "plant" can we assume you mean one or more generators?
If do, do you plan on replacing or rewinding the generator or just doing a DC to AC conversion with step up in voltage?

Tapatalk!
 
TDrake said:
I have two DC plants rated at 8000 amps each. I believe they are rated at 48 volts. I would like to convert them to 480 volt DC. I have done this before but do not remember and I do not want to ask my boss. I didn't see a formula for this in the NEC. Any ideas?
Click to expand...

What, pray tell, is your reasoning behind this? Usually if the voltage is kept low it's because it is CURRENT they are after. If you lower the current, you may change the way your "plant" (whatever it is) operates.
 
GoldDigger said:
And just in case the OP is not following completely, to get AC at any voltage requires an inverter.
When you say "plant" can we assume you mean one or more generators?
If do, do you plan on replacing or rewinding the generator or just doing a DC to AC conversion with step up in voltage?

Tapatalk!
Click to expand...
I think his question was about working out the the current on the 480V supply for his 8kA rectifier.
 
GoldDigger said:
And his 8kA rectifier will put out 50V? With 480AC input?
We are definitely missing some key information!
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It could with a controlled rectifier.phased back to give a low conduction angle.

But yes, some key information would be helpful.
See post #8.
 
Ah, but many of us get our daily exercise by jumping to conclusionsAh, but many of us get our daily exercise by jumping to conclusions

Gotta remember that line! - good one.So, to get tonight's exercise, what the heck uses 48 Vdc at about 40 kw that could be converted to 480Vac?
1. electric car with a VFD drive, but why go to 480V, does not make sense, so scratch that.
2. aerospace - Herndon VA has a North-Grumman plant, so may be aerospace; however, most aircraft going to 270 Vdc or 235 Vac 3P at 400 to 800 Hz. , so scratch that.
3. Navy projects going to 480 Vac, maybe that? Jump again and find that NG is teamed with GD for upgrades to next generation of ships. Some of the work is in VA?

SO, jump to conclusion that the old electric boat power distribution for sonar, etc was 48 Vdc, multiple 40kW or so systems. Navy is upgrading Virginia class to go to 2060, part of that may be 440 Vac vs 48 Vdc. assume OP confused 440 with 480?

Jump again to the seawater to jet and ship fuel conversion, assume massive amounts of seaborne nuclear power to convert sea water (and air) to hydrocarbons (and would be carbon neutral, wow!). Pilot plant electrolyzers envisioned, eh?

Now we have gotten OP in BIG trouble as that may be TOP SECRET (just fooling). http://dspace.mit.edu/bitstream/handle/1721.1/76359/823932001.pdf?sequence=1
http://www.industryweek.com/transportation/us-navy-game-changer-converting-seawater-fuel


So, final conclusion: Exercise is not good for you all the time <G> Another comment would be that if the OP has to ask a simple conversion question I sure hope he/she is NOT working on nuclear power equipment!!
 
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Smart $ said:
Sounded to me like he's after the current capability of the 480VAC output.
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48V 8kA DC in to 480Vac out would be a pretty unusual beast.
48Vdc is typical of anodising.
Posssibly telecoms. And we've done a few 7kA units for welding.
But these are outputs. Not inputs.
 
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