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Anonymous Poster

Testing SCRs

11/12/2008 10:50 AM

I've been testing thristors without the aid of a megger, but my question is that there are many probably ways of testing S.C.R's but it's not a D.C circuit as they are high power rated thristors rated at 1600amps at 380VAC. By using the ohm scale option on the multimeter i am able to get a typical value of 300K ohms - 700k ohms this should be a good thristor but some of these tests did not work on all of the SCR's(most bhave diffrent values and does not seem to be a concrete way of testing AC thyristors) so i thought maybe using the continuity option on the multimeter will be a good option as the thyristor requires a gate current before current can pass from anode to cathode so hence if i complete the circuit and the multimeter beeps without a gate current this should state that the thyristor is blown as no gate current was available.

Does this work as all the tests have proven to be accurate without any comebacks.

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#1

Re: How to test SCRs?

11/12/2008 1:28 PM

SCR's (or thyristors) act in a similar way to transistors, and as such can be tested in a similar way (with the diode test option on the multimeter).

Have you tried a google search "SCR test procedures" or "thyristor test"?

http://www.ab.com/support/abdrives/documentation/fb/1012.pdf

http://www.repairfaq.org/sam/semitest.htm#stthy

There are much more indepth Thyristor and SCR manuals available for download, but I don't have the links to the ones I have. A search of "SCR manual" or "Thyristor manual" will likely give some better results.

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#2

Re: Testing SCRs

11/12/2008 10:43 PM

You need to supply voltage across it at or near its rated voltage to check for breakdown problems, then fire the gate to see proper function while conducting. Most thrister manufacturers have application sheets to build simple test circuits. Test equipment manufacturers have testers that do thorough jobs for a few hundred dollars also.

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#3

Re: Testing SCRs

11/13/2008 7:28 AM

Take a look here:

http://www.huntron.com/ad/comptest.htm?gclid=CMny1_mS8pYCFQgRFQod7yCRZQ

I've used their Trackers for years and they are the most versatile troubleshooting tools I've ever seen. They generate their own user selectable test signals to test components in a power off state, but remaining in the circuit. You can even troubleshoot a board with no schematics if you have a known good one to compare it too.

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#4
In reply to #3

Re: Testing SCRs

11/27/2008 10:04 PM

Dear Sir

The link is not valid as it takes nowhere

regards

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