- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
coulter said:I'm not seeing that - here's why:
Once the armature is pulled in, and the pole pieces are touching, no further work (physics definition of work) is being done. So the analogy to a motor doesn't fit - no energy output.
I don't agree, the armature needs to constantly work against the springs that want to open the starter contacts, if not the starter would not open simply by disconnecting voltage to the coil.
And of course a low enough voltage will not be able to generate enough flux to keep the aramture sealed in. Most starters are designed to pull in at 85% nominal voltage and stay sealed in until 65% nominal voltage. And there are some starter designs that utilize economizer circuitry to reduce the current drawn by a closed starter coil, but I seem to recall that these employed a half wave rectified DC rather than simply a lower AC voltage.
I have never seen any measurements of the relationship of current to voltage when a starter is sealed in.