Isolated high voltage side measurement problem

[fernandomierhicks]

Hi:

I am testing a circuit that measures the voltage generated by a high voltage converter.

An off the shelf converter (EMCO) generates 1500 volts that are delivered to a load. A voltage divider divides this voltage by 10,000 and an isolation amplifier (AMC1100) is used to transfer the value to a microprocessor on the low side. A isolated dc-dc converter (ADUM6401) is used to power the amplifier on the isolated side.

**broken link removed**


The circuit functions very well until a short on the load happens on the high voltage side. When this happens the Dc-Dc Converter/ isolation amplifier start consuming much more current, after several shorts on the high voltage load these devices stop working altogether.

My power supply system has to be robust enough to handle shorts on the high voltage load.

When a short happens on the load, could there be voltage spikes induced on my dc-dc converter or amplifier and killing them? I have tryed putting voltage suppressor (suppressing 10 volts) both on the input and power supply pins of my amplifier with no good results.

Again the circuit works fine as long as no short happen on the load.

Thanks.

Fernando

 

[sf1628]

The maximum working voltage rating of the isolated DC-DC converter (ADUM6401) is 846V and highest allowable overvoltage is rated 6000V for 10 seconds based on the datasheet. The 1500V may be too high for the isolated DC-DC to handle since voltage stress is much higher than maximum working voltage rating (846V in this case). The 6000V rating is only for short duration such as 10 seconds.