I just started working on a furnace that uses the puck type thyristors for the main power switching. Every now and then, one of them blows and we replace it. We ususally use a mega tester to test wheteher they have blown or not i.e. put 250V across and short the gate to the anode. A zero impedance means its working fine. I am however not too sure how accurate this is for testing? In the data sheets of these thyristors it says they need to be clamped with 500kg of force in some cases. Now by running 24Vdc through these thyristors is this test being performed adequately? Does the device need to be clamped and does the amout of current running through it matter. If its rated for 1300A and I run 1A through it and t works, doees this mean it ill work for high amps or not?