Hello, i have a 1KV AC generator, i would like to design an AC DC converter for it, for low voltages like 220V AC it is easy to design a full bridge rectifier but it seems that i can't find capacitors rated in KV, any suggestion will be appreciated

thanks!

 

Use a transformer at the front end. 1 KV to 220 V. That's the way to go.

 

Is the 1KV AC and RMS value or a peak value, and are you wanting the DC output to be near 1000 VDC or 1,414 VDC as the case may be?

 

Is the 1KV AC and RMS value or a peak value, and are you wanting the DC output to be near 1000 VDC or 1,414 VDC as the case may be?

yes the output will be near 1,414 VDC

 

Hello, i have a 1KV AC generator, i would like to design an AC DC converter for it, for low voltages like 220V AC it is easy to design a full bridge rectifier but it seems that i can't find capacitors rated in KV, any suggestion will be appreciated

thanks!

Use several 500V capacitors in series with balancing resistors across each one.
How much current do you need?

 

Use several 500V capacitors in series with balancing resistors across each one.
How much current do you need?

like 7A

 

I might also consider a series inductor as well at that sort of current. Otherwise the peak currents may be too high for the generator.

 

Hello,

As for the capacitor needed, the largest kV range capacitors I could find id onlt 100 nF.
See the webpage of askjanfirst:
http://www.askjanfirst.de/dindex.htm?/k3.htm

Bertus

 

You will not find high voltage capacitors. The highest standard voltage is 500 volts, for this application I suggest a series string of capacitors, because if the supply is 1KV rms, the DC peak will be close to 1500. And for a 7 amp DC output without much ripple that will take a fair amount of capacitance.
What will that high voltage DC be powering? That makes a big difference in how much filtering is required. That supply will be delivering 7000 watts, quite a bit of power. So my other question is what is the system going to power? How much filtering will be required?

 

Is the generator single phase? Two wire? Or 2 phase? Three wire. Or 3 phase?
50/60 hz?

 

Hello, i have a 1KV AC generator, i would like to design an AC DC converter for it, for low voltages like 220V AC it is easy to design a full bridge rectifier but it seems that i can't find capacitors rated in KV, any suggestion will be appreciated

thanks!

I've never heard of a 1kv generator. Is it 1kv or 1kva?

 

For seven amps it will probably be a 7.5 KVA generator, which is a fair sized generator.
so really we need a lot more information in order to provide useful answers.

 

For seven amps it will probably be a 7.5 KVA generator, which is a fair sized generator.
so really we need a lot more information in order to provide useful answers.

Unless there is some confusion about the generator's capacity in the first plaice. Have you seen generators that output non-useful voltages like 1000v?

 

YES, I have. At one time I read an article about a ham who had an early tube transmitter and for the high voltage there was a generator that supplied 1200 volts, as I recall. So there did exist generators for assorted strange voltages, and some of them might still be around. And since this is an AC device, it might even be a rewound alternator. It may have slip rings or be a rotating permanent magnet type generator. Not the variety you can buy at the average Harbor Freight, but a one-off made long ago. OR ot may be from an ECM pod used in a recent conflict, prior to the availability of high power transistors. It may even have powered one of the early Navy sonar pulsers that used a high power tube. Rare but existing. Consider that the TS has given us no information except voltage and current.
And it is also possible that there is a bit of confusion.

 

YES, I have. At one time I read an article about a ham who had an early tube transmitter and for the high voltage there was a generator that supplied 1200 volts, as I recall. So there did exist generators for assorted strange voltages, and some of them might still be around. And since this is an AC device, it might even be a rewound alternator. It may have slip rings or be a rotating permanent magnet type generator. Not the variety you can buy at the average Harbor Freight, but a one-off made long ago. OR ot may be from an ECM pod used in a recent conflict, prior to the availability of high power transistors. It may even have powered one of the early Navy sonar pulsers that used a high power tube. Rare but existing. Consider that the TS has given us no information except voltage and current.
And it is also possible that there is a bit of confusion.

Sorry
1200v is not an odd voltage. The same transformer that converts 120v to 12v can be used for your "unusual" 1200v to 120vAC. Try again - so, I guess your answer is actually, no, you've never heard of an odd voltage generator.

 

The same transformer that converts 120v to 12v can be used for your "unusual" 1200v to 120vAC.

Have you tried it?

, i would like to design an AC DC converter for it

Why do you need DC? How well does the DC need to be filtered? What is the load?

 

The TS is asking to get 1000 volts DC from a generator that produces 1000 volts AC. And the 1200 volts was a DC generator producing plate voltage for an amateur radio transmitter, before-WW2.

NO, I have not attempted to apply ten times the designed primary voltage to a transformer. I have seen what happens when even just twice the rated primary voltage is applied to a transformer, which was that within an hour it was burned out. So while the turns ratio works in theory, the reactance fails to limit the current in reality, and the transformer over heats and fails.
When twice the voltage is applied, twice the current flows, and so the power losses generate four times the heat. So it can work for a short time only. Then it burns up.

 

1200v is not an odd voltage. The same transformer that converts 120v to 12v can be used for your "unusual" 1200v to 120vAC.

It can, but only at 500Hz (if the insulation doesn't break down, and if the core losses aren't too high)

 

500 Hz has not been mentioned in this thread, therefore I do not presume it. Possible, yes, but not mentioned. Ifthis is a rewound automotive alternator then 500Hz is reasonable. BUT that is not stated.

 

500 Hz has not been mentioned in this thread, therefore I do not presume it. Possible, yes, but not mentioned. Ifthis is a rewound automotive alternator then 500Hz is reasonable. BUT that is not stated.

I also assume a 50-60Hz generator, but the only way a 120V transformer could be run at 1200V is if the frequency were 10 times as high.