Testing an SCR
Testing an SCR
(OP)
I had a problem with the SCR module ( 2 in 1 package ) which has a high failure rate in our production. I want to know know what's wrong with this SCR. It is rated 2x130A 1200V. Anybody knows how to test this kind of SCR?





RE: Testing an SCR
RE: Testing an SCR
RE: Testing an SCR
What is the application?
If you apply this thyristor in the 480 volt, system unless you have a very good snubber circuit it could fail very easily.
You can also check the di/dt of the gate current against the factory specification and make sure the snubber circuit is properly sized.
You can also send the failed devices back to the manufacturer and ask for failure analyses.
RE: Testing an SCR
It's being used in a three phase 400V UPS system as part of the bypass circuit.If there's something wrong with the system, the UPS will turn to by-pass mode and the AC will pass thru this SCR and then to the load, thus bypassing the UPS.
RE: Testing an SCR
In your application he peak reverse voltage of the thyristor looks OK.
Make sure your snubber circuit is selected properly, and I can recommend an MOV against overvoltages. Also as was suggested earlier by jimthompson, check the gating circuit, make sure that the gate current duration, di/dt and peak value is in the specification. If you continuously gating the thyristor after turn on check with the manufacturer about it. Mostly the cases, the continuous gate current can be dropped after to the smaller value if the thyristor is turned on, and the thyristor current is higher than the latching current.
Still I can recommend to send the failed thyristor for failure analyses it will reveal the root cause of the problem.
RE: Testing an SCR
http://www.barthelectronics.com/tp_tlptesting.pdf
http://www.tucker.com/java/catalogs/Jul02/0702AComponentSemiConductor.pdf
etc. for SCR testers and testing methods
RE: Testing an SCR
The device specs will tell you the max dv/dt for that device.