Industrial connectors with fail-safe disconnect under cable tension (like MagSafe)
LEMO makes a nice line of "push-pull" latching connectors. I can't find it now, but I seem to recall seeing that they had a way of attaching a lanyard or cable to the release mechanism, so that if you pulled on it, the connector would separate. You could anchor the release cable to the electrical cable so that the former is shorter than the latter, such that if you
put enough tension on the far end of the cable, the connector will release before all of the slack is gone in the loop of electrical cable.

Of course, this will probably only work if the direction of the pull is more or less in-line with the axis of the connector, but you might be able to arrange some sort of ring-shaped guide that the cable must pass through that helps insure that this is the case.

I hope my description is clear; if not, I'll try to sketch what I have in mind.