Dumb question from someone who should know the answer

[Speakerguy]

OK, whenever I've needed a higher PIV diode I just grabbed a higher PIV diode. Well, now I'm making a bridge rectifier for 10-20kV, and all I have are 12kV diodes. Can I put two in series and get 24kV PIV, or will I just blow one up before the other?

 

[ericgibbs]

OK, whenever I've needed a higher PIV diode I just grabbed a higher PIV diode. Well, now I'm making a bridge rectifier for 10-20kV, and all I have are 12kV diodes. Can I put two in series and get 24kV PIV, or will I just blow one up before the other?

I have used diodes in series but at such higher voltages.

eg: two 400Vpiv in series with a 1M0 across each diode for 600V rectification.

I suppose you could get some 10MO HVR's and a couple of 1n0 at 12KVwkg?

Regards
EDIT:
**broken link removed**

 

[chemelec]

OK, whenever I've needed a higher PIV diode I just grabbed a higher PIV diode. Well, now I'm making a bridge rectifier for 10-20kV, and all I have are 12kV diodes. Can I put two in series and get 24kV PIV, or will I just blow one up before the other?

I have lots of 24Kv Diodes, if you need some.

 

[Speakerguy]

Yeah, I figured a resistor divider would be needed to ensure that the midpoint voltage would be 1/2 total, but I was hoping that maybe leakage currents through the diodes would set it. Hmm. Where do I get resistors with 10-12kV working voltages? I have some that will do that pulse but not continuous.

Hey chemelec,

Where did you find those? I might be interested in buying/trading to get some from you if they are not readily available. I got some interesting stuff around here at work that we'll never need again.

 

[Optikon]

Yeah, I figured a resistor divider would be needed to ensure that the midpoint voltage would be 1/2 total, but I was hoping that maybe leakage currents through the diodes would set it. Hmm. Where do I get resistors with 10-12kV working voltages? I have some that will do that pulse but not continuous.

Hey chemelec,

Where did you find those? I might be interested in buying/trading to get some from you if they are not readily available. I got some interesting stuff around here at work that we'll never need again.

leakage currents will set the voltage sharing (ballasting). so i fyou have one low leakage type in series with a bunch of crummy(higher leakage) types, that one could take on the full voltage and breakdown.

High voltage diodes and resistors are available but rare and expensive! Such is the struggle with HV design.

 

[chemelec]

leakage currents will set the voltage sharing (ballasting). so i fyou have one low leakage type in series with a bunch of crummy(higher leakage) types, that one could take on the full voltage and breakdown.

High voltage diodes and resistors are available but rare and expensive! Such is the struggle with HV design.

Yes, High Voltage Resistors are Expensive.
But I have some of them Also, Made by Dale/Vishay.
But the use of these Also Reduces the Output Current.

The Diodes I have are rated at 24Kv and 2 Ma Continuous.
10 Ma Intermittant. Part Number SHV-24, Made by "Sanken".
And I can sell them Fairly Cheaply, I have about 1000 of them.
Email Me if you want more info.

Include Quantity and Where you Live, (Country) so I can Include the Shipping cost.

Trade, Maybe??, Depends on what you have in mind?

 

[Optikon]

Yes, High Voltage Resistors are Expensive.
But I have some of them Also, Made by Dale/Vishay.
But the use of these Also Reduces the Output Current.

The Diodes I have are rated at 24Kv and 2 Ma Continuous.
10 Ma Intermittant. Part Number SHV-24, Made by "Sanken".
And I can sell them Fairly Cheaply, I have about 1000 of them.
Email Me if you want more info.

Include Quantity and Where you Live, (Country) so I can Include the Shipping cost.

Trade, Maybe??, Depends on what you have in mind?

I also have plenty of HV resistors and diodes too but none for sale. Also the general advise I give out is to avoid them if you can due to rarity & cost but then again, I'm not trying to sell them!

 

[Hero999]

I have used diodes in series but at such higher voltages.

eg: two 400Vpiv in series with a 1M0 across each diode for 600V rectification.

I suppose you could get some 10MO HVR's and a couple of 1n0 at 12KVwkg?

Regards
EDIT:
**broken link removed**

I would use a higher value resistor for such high voltaages.

For 20kV I would use 10M0 possibly even 22M0.

 

[chemelec]

I also have plenty of HV resistors and diodes too but none for sale. Also the general advise I give out is to avoid them if you can due to rarity & cost but then again, I'm not trying to sell them!

Typically I Sell these diodes for $1.50 Each in Singles, But I can Sell them for MUCH LESS.
I also have a Few Thousand, "BY711" Diodes. Rated at 2 Ma and 16 Kv. They are Cheaper yet.

The HV Resistors I have, Are Fairly expensive, but it also depends on How High of Voltage and the Wattage.

I have HV resistors up to 10 watts, some up to 37,500 Volts and some up to 10 Tera Ohms, 10,000 Meg-Ohms.

** But Don't Breath on the 10 Tera-Ohms or handle them with Bare Hands, as that will change there Resistance Value.

All these parts are Surplus from my Previous Business.

Take care.....Gary

 

[chemelec]

I would use a higher value resistor for such high voltaages.

For 20kV I would use 10M0 possibly even 22M0.

A Nominal Value for this Purpose is a Resistor that allows aproximately 1/10 the Nominal Output Current to flow through it at the Rated Voltage out.

 

[Hero999]

Why?

The voltage ballancing resistors are only required to ensure the voltage drop across each diode is the same as their leakage currents are likely to vary significantly. I would look up the leagake current for the diodes at the voltage you want to use them at and calculate the resistor values accordingly.