Well, that doesn't seem right. Something must be miswired. Is the "HV Sol" power ground tied to the 24V ground?
That's entirely possible. I'll be going over it again to be sure. Yes they share a common ground circuit. The main power supply feeds several voltages used by the whole system.
What's the contactor resistance?
Definitely, sounds like a isolated ground, you should measure something there!
Also that's why relays are still used a lot, they provide a simple method of isolation.
The contactors coil resistance is ~3 ohms. I know it seams really low, but its low resistance is not much of an issue, due to it's extremely low duty cycle...and a fairly high mechanical resistance it has to overcome. It only activates for about 300 milliseconds to overcome the spring tension and close the contact, a mechanical interlock toggles over to latch the output. A secondary relay coil is activated later to unlatch the contactor contact interlock to release the contact and open the circuit.
As a side note, my test setup involves not using the full voltages specified here, as I don't currently have a 40v supply handy, and I'm not currently able to take the machine down for testing.
As an alternative, I'm driving the "low voltage" 24v side currently with a 12v supply and my "40v" is being substituted with a 18v supply using a couple incandescent bulbs in series as a "load" to indicate the switching. (Since it is a purely resistive load, there is no flyback diode attached to it) I've also tried measuring continuity through the FET with the VOM to check for a path through to ground when activated to see if it reads a "short" but nothing seems right Perhaps my testing methods are flawed... Perhaps my wiring is wrong. I will be double checking it to be sure.
Thanks for the help guys, it's much appreciated 👍🏻