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carrotSnack

Thu Dec 22 2011, 06:57AM

Registered Member #4115 Joined: Fri Sept 30 2011, 01:13PM
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Posts: 12

Hi all, will this

thyristor be suitable for a switch? My only doubt is that it's referred to as a PCT (Phase Control Thyristor) instead of a SCR. I've used the small 3 pin SCRs before on breadboards but I'm wondering how would I use this?
Thanks for the advice.

PSCG

Thu Dec 22 2011, 12:57PM

Registered Member #3792 Joined: Sun Mar 27 2011, 06:07PM
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Posts: 136

Yes, it can be used as a coilgun switch (and it is a big one!).

Make sure that you will not exceed the operating parameters when working on pulse operation. Also, make sure that you have clamped it down correctly (apply the rated pressure between the cathode and anode sides) for the SCR to conduct both electricity and generated heat (if any).

carrotSnack

Fri Dec 23 2011, 12:27PM

Registered Member #4115 Joined: Fri Sept 30 2011, 01:13PM
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Posts: 12

Thanks for the info.
Can you tell me more about the pressure I need to apply to it (and why)? Will it just work sitting on a table or will I need to clamp it down for it to operate?
Also will it have 3 leads or connections that operate the same as a small breadboard SCR?

PSCG

Fri Dec 23 2011, 01:31PM

Registered Member #3792 Joined: Sun Mar 27 2011, 06:07PM
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Posts: 136

For "puck" SCR's, pressure between the cathode and the anode sides is essential for it to conduct the applied electricity and generated heat (for continuous operation). The silicon die of this type of SCR's is not physically connected to the end terminals. That means without any applied pressure, it cannot conduct. So, clamping is necessary.

For the clamping force, you can take a look in the datasheet (under Thermal and Mechanical Specifications). As documented, mounting force (clamping force) is 4900N - 500Kg.

These SCR's are not operating differently than the TO - 220 packages (or any other type of package). The only differences are the operating parameters (can conduct higher voltages and currents than the smaller SCR's) and the necessity of clamping to work correctly. The top and the bottom sides are the the anode and cathode leads (not necessarily with that order) and the small lead is the gate. Connections are the same as with the small breadboard SCR's.

You can use this link to download the outline dimensions.

carrotSnack

Sat Dec 24 2011, 05:14AM

Registered Member #4115 Joined: Fri Sept 30 2011, 01:13PM
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Posts: 12

I'm having trouble finding a puck scr clamp, even the big distributor I'm using

does't seem to have any. I'm not sure how I would determine the pressure given by a general purpose clamp or vice.
Perhaps a stud scr would be better if I can't find a suitable clamp.

EDIT: If I have issues with the hockey puk SCR then I'm looking at this one instead

. One thing is that the current rise rate of the hockey puk is 1000 A/Âµs while the stud is 300 A/Âµs, this is only a bottleneck right? Assuming the rise of current is <300 A/Âµs will there be any difference between the two?

PSCG

Sat Dec 24 2011, 09:40AM

Registered Member #3792 Joined: Sun Mar 27 2011, 06:07PM
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Posts: 136

di/dt is lower than the puck SCR, so it would be more difficult to use it if you are planning to make an induction accelerator or can crusher (that's why puck type is popular in these projects).

Finding puck SCR clamps can be difficult. Many are homebrewing them. Take a look at this thread. You may find it useful if you want to make your own clamp.

For pressure determination you can use this PDF.

carrotSnack

Sat Dec 24 2011, 10:42AM

Registered Member #4115 Joined: Fri Sept 30 2011, 01:13PM
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Posts: 12

Thank you for the links, I'll have a look if it's worth making a home made clamp or not.
With the di/dt, assuming it was only going to be 100 A/Âµs then it wouldn't make any difference which one I used right? I'm still leaning towards the puck but I don't think the current will rise any faster than 300 A/Âµs (although it may for any future experiments).

PSCG

Sat Dec 24 2011, 04:30PM

Registered Member #3792 Joined: Sun Mar 27 2011, 06:07PM
Location:
Posts: 136

Yes, with only 100A/uS it won't matter. The only difference is that the puck type will allow much higher di/dt ratio than the stud type.

vk2fro

Sun Jan 22 2012, 02:09PM

Registered Member #3930 Joined: Sun Jun 05 2011, 07:27PM
Location: Sydney, Australia
Posts: 33

Centrx make clamps for these puck style SCR's. Shoot them an email and ask. They'll get some details off you (like how much clamping force, how big the puck is etc), and will make a nice clamp for you. See my thread (bens foray into...) in this forum t see my puck and clamp. I have the same case style as the vishay one you are looking at, but mines a westcode semiconductor puck :)

My clamp cost $39.95 + postage from memory.

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