What is this device?I have a device that seems to output 5v. When the device is triggered the voltage drops to 2.5v.
Don't understand what you're asking.is there a relay that would trip with the voltage drop at all?

WE are given NO description of what that device might be, we are given no description of what "triggered" does, and we are given no description of what, if any, load is being powered.I have a weird situation.
I have a device that seems to output 5v. When the device is triggered the voltage drops to 2.5v. is there a relay that would trip with the voltage drop at all?