SCR Tester – Homemade DIY SCR Powerblock Tester

Here we take a look at an SCR Tester we built to test large power block SCR which required more current than commercially available small testers could provide.

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This prototype SCR Testing device tests the Gate Trigger Current (IGT), Latching Current (IL) and Holding Current (IH) of Powerblock SCR Modules (Thyristors). The dial, led indicator and amp panel on the left are for the gate trigger and current. The dial, led indicator and amp panel on the right are for the A/K Latch and Hold Current. When the trigger button is pressed current must be increased with the dial until the right led lights – that is the required Gate Trigger Current displayed on the amp panel. Now the A/K load current must be increased until the right led lights and stays on after the trigger is released. Then the SCR is latched in the On state and the current displayed on the amp panel is the required Latching Current (IL). Current can be lowered down to the Holding Current (IH) for the specific SCR under test and still stay in the On state (check data sheets). If current falls below (IH) the SCR will turn off. This prototype was made since I couldn’t find such a product on the market to test large Powerblock SCRs requiring high IGT and IL currents. Next project after I make the final polished version of this tool is an (IPM) Intellimod IGBT tester. Edit: 2014_04 120vac input to regulated 48VDC supply. Wire wound variable resistors for dials. This unit is designed to deliver only a few amps max.

I own a few different commercial scr tester, semiconductor testers, thysitor testers but none of them provided over 90 milliamps of current to the gate and would not trigger the large power block SCRs.


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