PCAN-USB Pro FD: What happens when galvanic isolation voltage is exceeded?

[MarioW]

Hi,

we are using normally PCAN-USB Pro FD devices to measure can traffic on our systems. Now for a different device we are thinking of using PCAN-M.2 four channel modules, but the isolation voltage drops from 500V to 300V (each channel to usb/pci).

The systems we are working on are in principial constructed this way:
PC or Laptop connected to AC-grid: CAN to system (e.g. Truck) with components based on the 24V chassis ground (floating in regard to the AC-grid), and another CAN channel to a DCDC converter with a voltage based on the battery level (e.g. up to 800V, isolation resistance to chassis > 400kOhm (500Ohm/V))

My question(s):
* What happens when the voltage between two channels or one channel to the PC is exceeded? Is anything destroyed or is there "only" a build up of a "ground loop" which trys to equalize the floating voltage levels?
* Are the used devices (PCAN-USB Pro FD/ PCAN-M.2) the right decision for this? Should there be for safety issues a coupling of the CAN-GNDs and the USB/PCI-GND by special electronic parts like tvs-diodes or capacitors?
* What other things I have to think of in this application?
* Is there a good internet link where the basics is described to understand whats happening?

Thanks for your replys!

Best regards Mario

[a.staat]

Hi,
when you exceed the specified isolation voltage a flashover can happen inside the coil or at the PCB.
This will damaged the isolation and reduce flash-over voltage.

If you have a permanently potential difference of 800V you should
use a PCAN-Repeater to connect this CAN-Bus to PCAN-USB or M.2