mxs said:
... plus I have not seen other DC contactors where the manufacturer states two voltages ... coil and contact and at that those two being different.
It is common for contactors to use a different coil voltage (often 12v) vs the contact voltage, as there is often a low-voltage control system for the high-voltage traction system.
mxs said:
Any idea what will physically happen?
As previously noted, the contactor may not be able to break the arc, if it needs to disconnect under load.
That could result in welding of the contacts, which means the contactor *can't* disconnect the circuit anymore.
It could result in arc damage to the contacts, increasing their resistance, causing voltage drop across them, and causing the contactor to heat up under load. Or the increased resistance could be so high that the system doesn't operate normally (or at all) due to the voltage drop across it and the decreased current avalable thru it.
BTW, the most common difference between between a simple "relay" and a "contactor" is that contactors are often environmentally sealed, with neutral gas filling them so the normal compounds in air wont' react during the arcing that happens inside, to minimize contact damage over time.
Some relays are also built this way, but most are not.
If it's useful, these are a couple of contactor manufacturers commonly used in EV conversions and such:
https://www.gigavac.com/catalog/power-products
https://www.te.com/usa-en/products/relays-contactors-switches/contactors/automotive-contactors.html
or all versions
https://www.te.com/usa-en/products/relays-contactors-switches/contactors.html
Other threads with contactor info
https://endless-sphere.com/forums/search.php?keywords=contactor*&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search