Inverter grade scr vs. phase control scr
Inverter grade scr vs. phase control scr
(OP)
I would like to know what electrical parameters make the difference between a inverter grade thyrister and a phase control thyrister? I am tring to cross refrence an old obsolete inverter grade thyrister in an attemp to make a quick repair to a UPS system at my facility that has a shorted scr in the ocillator.





RE: Inverter grade scr vs. phase control scr
Basically, if you can, look up the performance specs for the SCR you have and match them. If you don't have data sheets, get hold of a decent thyristor supplier, like Westcode, and give them the situation, they will have a solution for you I'm sure.
"Will work for (the memory of) salami"
RE: Inverter grade scr vs. phase control scr
RE: Inverter grade scr vs. phase control scr
Phase control isn't critical when it comes to turn-off time. The commutation takes place sooner or later anyhow.
In an inverter application (yes, there were VFDs with thyristors once upon a time), the turn off time is critical. So you need fast turn off thyristors. That is where the term "inverter grade" comes in.
But, today? You don't build VFDs with thyristors in the inverter part - do you? No, not really. Unless you are building induction heaters, cycloconverters or CSI. Especially the induction heaters working with 400 Hz and more need fast turn off thyristors.
Is your application induction heating/welding or something similar?
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Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: Inverter grade scr vs. phase control scr
RE: Inverter grade scr vs. phase control scr
So you are saying that "inverter grade" is the new name for GTO thyristors then? That would have made it much more clear to an old fart like me. Clever marketing if so, because GTOs got a bad rep a few years ago when transistor drives railed against them in the early days. It was not not deserved, it was just negative selling, but it happened nonetheless. So it sounds like the mfrs have "reinvented" the product by giving it a new moniker.
"Will work for (the memory of) salami"
RE: Inverter grade scr vs. phase control scr
No, it's not a GTO. Inverter-grade thyristors are much the same four-layer device as a regular thyristor but with a different gate geometry which allows it to quickly regain blocking capability. Some discussion from Westcode in this document. http://www.westcode.com/publicity/present/prod_pre...
RE: Inverter grade scr vs. phase control scr
"Will work for (the memory of) salami"
RE: Inverter grade scr vs. phase control scr
As the newer devices came up at low power first, smaller ratings of fast thyristors ( up to 100 A, up to 1800 V) were replaced first in applications like UPS and hence the semiconductor suppliers discontinued the components approx. 20 years ago. The higher rating followed as soon as higher rated IGBTs and GTOs were available and widely accepted.
The only application were fast thyristors are still used today is high power induction heating at moderate frequency and beside spare part business this is the only market for these parts today. Westcode / IXYS is the only major supplier still active in the business.
If you can post the type designation and/ or a photo I might be able to support you in finding a replacement part, if you really want to repair.
RE: Inverter grade scr vs. phase control scr