[OT Hardware suggestions] 24 channels at 1500 Volts

[Ben]

I am putting together an app that needs to check a total of 24 singals with a max voltage of 1500 volts. I am hesitant to put a voltage divider across that potetial because the load I will present to this DUT is already 26 M ohms AND I'd have to add scaling to compensate for the variations of the resistors. 

What would you recomend?

The manual version of the test is using a Fluke DMM with a HV probe.

If I go with an equivelent DMM and HV probe I will need relays or some type of mux to move the leads.

Since I am still drawing this up, I'd like to hear about other suggestions.

Thank you for reading!

Ben

[James_W]

No suggestions here, but that project sounds AWESOME!!!

Maybe it's just the big numbers involved that are exiting me!

[Wayne.C]

Ben,

Quite a few of our test fixtures include a hipot test.  We use Magnecraft W102HVX-3 high voltage reed relays to switch the HV.  http://www.magnecraft.com/library/archive/103_Section6.pdf

[AnalogKid2DigitalMan]

Wayne beat me to it- I was going to suggest the same 102 series, I've used them in hi-pot testing applications before too.

-AK2DM

[mikealder]

HV Cable testing we use DITMCO, channel counts can be as low as a hundred or in to the tens of thousands with the system running at 1500V where required, might be worth looking at one of their switch racks, even an old second hand 19" rack switch would give a 500 channel switch each rated at up to 1500V - Mike

[Henrik_Volkers]

The LTC6802 Batterie stack monitor came to my mind.  datasheet tell something >1kV 😮

continuous mode? Dynamic range?

Needed resolution? 

Differential or SE?

TI has 20bit 'low' current input 32 channel ADC's (DDC232) for low PD current ...  but would involve some HQ high value R and higher isolated PCBs 😉

I assume you might have difficulties to provide more information? 

[Henrik_Volkers]

2. thought: Use 24 10G Rs (Vishay makes good ones) and use any low voltage relay... just tie it to GND, connect (via MUX)  a pF C , open the relay and monitor the voltage ramp. spend one more channel with a V_ref and a R_ref (doesn't need to be 1kV 😉 ) . You stay with  R calibration in software and the C scaling, but leave the switching in low voltage. (A neon bulb make a good limiter 😉 )

Now use a negative V_ref, a comparator and a timer and wellcome back to the good old dual slope 😄 😄

[Ben]

It looks like I am going to "roll-my-own" based on digikey part number 725-1039-nd with contacts rated at 7KV.

I still remember how to solder so the rest is up to me.

Ben