Output monitor of high voltage module

[ozzy]

Hi all,


I have recently come across a problem regarding high voltage modules.
Having looked at the Ultravolt 10A-25A modules it mentions:

“The 10A→25A Series features a 1000:1 voltage monitor. The monitor has
an output impedance calibrated for use with a 10 MegΩ input impedance
meter. Overall accuracy is ±2.5% with a temperature coefficient of
±200 ppm per °Câ€.

I am actually in need of a Voltage readback using 12 bit ADC (ie ~
4000:1 needed) giving a 0 to full scale, for 0 to maximum voltage.
The +/-2.5% error can be cancelled at the input (0-5V input generating
0-10KV output) or at the voltage monitor output.

So should I just abandon the use of the voltage monitor and use a
potential divider (along with ADC) to get the accuracy I want. My
circuit will be floating on 2KV – would photo-transistors be the way
to go for isolation purposes (and if so where could they be best
utilised)?

Any help on the above issues would be much appreciated.


Regards,


Ozzy.

 

[Rene Tschaggelar]

Hi all,


I have recently come across a problem regarding high voltage modules.
Having looked at the Ultravolt 10A-25A modules it mentions:

“The 10A→25A Series features a 1000:1 voltage monitor. The monitor has
an output impedance calibrated for use with a 10 MegΩ input impedance
meter. Overall accuracy is ±2.5% with a temperature coefficient of
±200 ppm per °Câ€.

I am actually in need of a Voltage readback using 12 bit ADC (ie ~
4000:1 needed) giving a 0 to full scale, for 0 to maximum voltage.
The +/-2.5% error can be cancelled at the input (0-5V input generating
0-10KV output) or at the voltage monitor output.

So should I just abandon the use of the voltage monitor and use a
potential divider (along with ADC) to get the accuracy I want. My
circuit will be floating on 2KV – would photo-transistors be the way
to go for isolation purposes (and if so where could they be best
utilised)?

Any help on the above issues would be much appreciated.

I'd take that 10Meg output, provide a 10Meg resistor
together with a fet input opamp in a voltage follower
configuration.

Rene