Author Topic: Best way to switch large current spikes?  (Read 2294 times)

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Offline s3c

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Best way to switch large current spikes?
« on: October 07, 2010, 06:59:41 pm »
I'm currently working on a project that requires me to discharge a cap with virtually no load, ie, just short it out. I'm working with a 100uF cap charged at 300V and above. What would be the best way to switch the connection? Will transistors/fets be able to handle such large current spikes?
 

Offline Time

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Re: Best way to switch large current spikes?
« Reply #1 on: October 07, 2010, 07:03:23 pm »
There are switching devices that can handle that just fine.  Mosfets, IGBTs, SCRs just to name a few.  Depends on how fast you need to switch it and how much money you have really.
-Time
 

Offline Simon

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Re: Best way to switch large current spikes?
« Reply #2 on: October 07, 2010, 07:08:10 pm »
A general use mosfet rated at over 300V that can handle up to 30+ amps ? if your worried about blowing it put a small resistor in series with the mosfet channel to control the current,
 

Offline Zad

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Re: Best way to switch large current spikes?
« Reply #3 on: October 07, 2010, 09:01:05 pm »
Be aware that crowbar-ing caps can sometimes make them go BANG as they heat up and boil the dielectric.

Offline s3c

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Re: Best way to switch large current spikes?
« Reply #4 on: October 08, 2010, 06:18:36 am »
I haven't heard of IGBT's and SCR's before, looked them up and I think an SCR is near perfect, thanks Time. I'm kinda cautious about using parts with current ratings below 100A, the cap will most likely have a resistance to keep the current below that but since I have no data on it there's no way to know. A load resistor is probably a good idea... Thanks all.
 

Offline Murphy

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Re: Best way to switch large current spikes?
« Reply #5 on: October 08, 2010, 09:03:46 pm »
SCRs do the trick, they can handle huge pulse currents many times what their continuous rating is.
 


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