Current Meter

[TK5EP]

Hi Sougata,

Thanks for the ideas, my wish is to use no different supply on the HV side to supply the amplifier.
I attached a GIF with the principle of the supply. You see that the supplies are not referenced to ground but to cathode of the tube.
For the 350 V, i could make my measure on the grounded side of the supply, current can flow in both directions with max 50 mA.
The 3500V HV will draw about 800-900 mA.
The 36V only a few mA.

Greetings,

Hi there,

Sorry to catch this thread late. I manufacture series of PIC controlled thyristor based battery charger. For low cost designs I use a piece of wire acting as a shunt in the negative line and then a LM358 for the amplification. It is safe to use it in a HV line also as long as it is referenced to ground. You can use a programmable gain IA like AD620 for your differential measurement needs and couple it to a linear optocoupler like the Vishay IL300. This gives far accurate results than the V/F approach and is cheaper. The only problem is you need another supply. Consider using the IRF PVI series of optos to make a 5ma supply isolated DC-DC converter as well as linear output opto. Maxim has got a very good appnote on high side current measurement (1KV).

Whew! Enough gyans...

If you could post a specific issue with detailed electrical parameter then I might find something on my Hard drive.

BTW I always use a PIC with 10bits res. If thats enough then go on.

Regards

Sougata