Please help me with this Capacitor, SCR, low resistance coil problem!!

[Sanjay kumar]

I want to discharge capacitor in micro seconds, In order to to that I used very low resistance coil but When capacitor is discharged,


SCR kinda blow up, meaning the positive & negative got connected together because of low resistance.


What can we place in negative terminal to make sure that positive & negative does not gets connected! ?


Since coil resistance is very low!


Like- Diode or something?

 

[James]

How much energy are you trying to discharge?

 

[Lucien Nunes]

Are you sure it's the peak current that is killing the SCR and not the impulse voltage when the LC circuit rings?

 

[pc1966]

Well for a start the + & - are wrong way for the SCR! (or the SCR is shown wrong-way round and gate/cathode are both references to '-').

First thing to check is the I2t of the pulse and see if it is below the SCR rating. If not you need a bigger SCR or some other more exotic choice of switching device, or some means to trigger parallel SCRs very precisely and to have some current-sharing impedance like a low R high-current resistor, or split the capacitor bank per-SCR (can all be charged in parallel with modest resistors from the DC source though).

Second thing is the above about back-EMF, though usually SCR/triacs simply switch in to conduction on over-voltage and so are a damn sight hardier then transistors/MOSFET for surges of that sort.
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Also make sure when you trigger the SCR you do so with a fast pulse as high as the gate is rated for. You don't want the SCR to transition slowly in to conduction otherwise the internal heading of the silicon is more localised and peak rating lower as a result.

 

[marconi]

Aadish Manrai: Before I decide whether to help you I need to know more about your level of electrical knowledge, your age and also the reason why you want to discharge the capacitor into a low resistance coil switched by a thyristor - I have an inkling* of two application it could be.

* see:

inkling meaning - Recherche Google - https://www.google.com/search?q=inkling+meaning&rlz=1C1GCEA_enGB822GB822&oq=inkling+&aqs=chrome.1.69i57j0l5j46j0.3314j1j15&sourceid=chrome&ie=UTF-8