OCD testing
Graham Armitage, Fri Jan 16 2015, 02:54PMLooking for some tips on testing OCD on the UD2.5 or 2.7 drivers. As the circuit indicates, the rectified signal from the CT is across the 5.1ohm resistor. When running with the interrupter, the duty cycle is so low that this does pose a problem from the little resistor. however, if testing with a signal generator, a 1A current through that resistor will fry it. Without having to remove the resistor for testing, does anyone have any other tricks they use?
Re: OCD testing
JoeBonanno, Fri Jan 16 2015, 03:23PM
actually, i don't test the OCD until all system was ready. i simply set it as lower as possible and raise it gradually while the bridge running! whit my bridge, the OCD fire instantaneously at low setting. then i rise it until about 1kA ready for the future testing with the secondary in place!
JoeBonanno, Fri Jan 16 2015, 03:23PM
actually, i don't test the OCD until all system was ready. i simply set it as lower as possible and raise it gradually while the bridge running! whit my bridge, the OCD fire instantaneously at low setting. then i rise it until about 1kA ready for the future testing with the secondary in place!
Re: OCD testing
loneoceans, Fri Jan 16 2015, 06:00PM
The OCD signal doesn't need to be constantly on. You can simply add a small voltage across the resistor with the trip point set lower. This could be done with a small bench DC power supply with a small switch to simulate OCD crossing, so you don't need to worry about burning out the resistor. To check you can scope the gate drive outputs. The OCD should hold for around 1ms until the next turn-on from the interrupter.
loneoceans, Fri Jan 16 2015, 06:00PM
The OCD signal doesn't need to be constantly on. You can simply add a small voltage across the resistor with the trip point set lower. This could be done with a small bench DC power supply with a small switch to simulate OCD crossing, so you don't need to worry about burning out the resistor. To check you can scope the gate drive outputs. The OCD should hold for around 1ms until the next turn-on from the interrupter.
Re: OCD testing
Graham Armitage, Fri Jan 16 2015, 06:28PM
Ah, got it - so you are just setting a DC voltage and switching on for a short time to see if the LED flashes. Makes sense.
Thanks
Graham Armitage, Fri Jan 16 2015, 06:28PM
Ah, got it - so you are just setting a DC voltage and switching on for a short time to see if the LED flashes. Makes sense.
Thanks
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