Need help with 1000 VDC high speed switching circuit
Need help with 1000 VDC high speed switching circuit
(OP)
Hello,
I need to create a rotating electric field using DC. In summary, imagine 8 vertical steel rods arranged in a circle, with a 9th steel rod in the middle of the circle. Like a small circular fence with a rod in the middle of it. I need to energize each of the outer rods at 1000VDC with the middle pole at DC common potential. The rods have to be energized one at a time for 5mS at a time. There will be almost no current flow. The purpose of this is to create an electric field.
So, how does one create a high voltage high speed switching apparatus that is safe? Any ideas?
I need to create a rotating electric field using DC. In summary, imagine 8 vertical steel rods arranged in a circle, with a 9th steel rod in the middle of the circle. Like a small circular fence with a rod in the middle of it. I need to energize each of the outer rods at 1000VDC with the middle pole at DC common potential. The rods have to be energized one at a time for 5mS at a time. There will be almost no current flow. The purpose of this is to create an electric field.
So, how does one create a high voltage high speed switching apparatus that is safe? Any ideas?





RE: Need help with 1000 VDC high speed switching circuit
Though "high-voltage" and "high-speed" rarely go together with "safe"... I guess it depends upon your definition of "safe", then.
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Need help with 1000 VDC high speed switching circuit
Now, if you can handle about 0.2 to 0.3 msec delay, and you're not concerned with your rods possibly becomming shorted, then there are available solid-state relays that can do the job. These relays are in dip packages, but this will still be easier than switching with N-channel MOSFETS, and designing a gate-drive that will be above ground by over 1000V.
Look at Panasonic AQV258 or AQV259, 1000V and 1500V 30mA and 20mA devices. Theses are photo-MOS devices. The control side is basically a LED.
On the output of these I would put a resistor to ground to discharge the rods. Otherwise, your rods will be capacitors that just charge-up to 1000V and never discharge before becomming energized again. You may want to measure the capacitance of the rod to size the resistor for the discharge.
If the rods are really, really long, or very close to the common rod, then the capacitance could be high enough to create a discharge issue, depending upon your actual application and rate-of-discharge needed. In that case, you may need to use additional relays (with a resistor to limit max current below the relay rating) to discharge the rods.
RE: Need help with 1000 VDC high speed switching circuit
Thanks also for the note on the resistor on the rods. I had not thought of that.
EE
RE: Need help with 1000 VDC high speed switching circuit
1000 volts, 1 cm, shouldn't.
RE: Need help with 1000 VDC high speed switching circuit
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Need help with 1000 VDC high speed switching circuit
RE: Need help with 1000 VDC high speed switching circuit
RE: Need help with 1000 VDC high speed switching circuit
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Need help with 1000 VDC high speed switching circuit
RE: Need help with 1000 VDC high speed switching circuit
LV, MV and HV - it probably depends on where you are. The rule here (EU) is that all machines up to 1 kV are LV machines. May be different where you are.
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Need help with 1000 VDC high speed switching circuit
If you're concerned, use a conformal coating. The coating could be no more than an appropriate RTV brushed over the part and on the opposite side of the board where the leads come through. You could also bend the leads outwards and make the dip into a gull-wing surface mount device.
RE: Need help with 1000 VDC high speed switching circuit
Appropriate means non-acidic. If it smells like vinegar - don't use it on electronics.
RE: Need help with 1000 VDC high speed switching circuit
So apparently those little Panasonic dips can actually work. It's hard to believe. But they are only a few dollars each. I think it would be worth $150 to find out.
Thanks for your suggestions.
EE
RE: Need help with 1000 VDC high speed switching circuit
RE: Need help with 1000 VDC high speed switching circuit
Keith Cress
kcress - http://www.flaminsystems.com