SCR power modules

[welderrprman]

I recently had to replace an 82-0545/VSK300-04 scr power module on a welder. This is a 300 amp module with 2 scr's internal. It operates in a push pull fashion to produced a rectified dc output for a constant voltage welder. Right now certain electronic components are scarce and I had to resort to Ali Baba for the replacement part. On the original part the anodes are both connected to the heat sink. On the AliBaba part the heat sink was isolated and the gate terminals were reversed. The anode terminal on the original was missing and on the replacement part it was the output terminal. Both items have the same part #. basically a VSKV300-04. Does anyone know which type is more thermally efficient with regards to dissipating heat? Also, I tried getting a spec sheet for this module and so far have been unable. Anyone know where to get a spec sheet?
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[rjenkinsgb]

Thyristor modules like that are normally isolated from the base.

I've never seen one in that package with a rating much over 150A; just having a search through, there is one maker that does a 260A one:

IXYS MCMA260P1600YA, Dual Thyristor Module 1600V, 260A 220mA | RS

uk.rs-online.com

Note the picture is wrong on that & shows a single thyristor + diode, but the datasheet shows it as a dual thyristor.


Most makers use a heavier package with bigger terminals from 150 - 200A upwards, like this:

Infineon TT320N16SOFHPSA1, Thyristor Module 1600V, 320A 150mA | RS

uk.rs-online.com

Semikron SKKT 273/16 E, Dual Thyristor Module 1600V, 320A 150mA | RS

uk.rs-online.com

I can only guess what the one you have is rated at, as searching for it gives a single Aliexpress link and your post!
I suspect it's a much lower rating one that is marked specially for that welder manufacturer.

It may be a 150A type and they are rating it for output current (using each half alternately at 50% duty) or it could just be a made up part number...

Two parts with the same genuine part number do not have totally different configurations, so again, it looks like other devices relabelled for that welder maker.