I'm trying to measure the activation time of a pull-type solenoid.
When the solenoid doesn't have a load connected to it, you can measure its activation time through the current it consumes. At first, the solenoid will consume current until the magnetic field is strong enough to move the armature, at which point the current consumption decreases until the armature has reached its holding position. At that point the current will rise a bit more until it stabilizes.
However, if there is a load attached to the armature, the curve of current consumption never dips, which means that you can't quite tell at what point the armature is fully pulled in.
I'm wondering what technique could be used or is standard for measuring the time it takes the armature to reach the end position with a load.
I've thought of making the load close a circuit so you could measure the time between activation of the solenoid and the closing of the measuring circuit but I'm wondering if there are other approaches which I haven't thought of.
(p.s. if this is off-topic let me know and I'll remove the question)
Edit: Preferably the solution can be embedded in a machine with up to 1000 solenoids. This means that the added hardware (cost for example) needs to be somewhat realistic (i.e. no 200$ camera per solenoid ;) )