Jadnashua
Retired Defense Industry Engineer xxx
Contactor coils do NOT like less than their rated input voltage (which may be a range). The contact ratings of the contactor power leads are a maximum, and using lower voltages (and current) on them than specified won't be a problem. Some motor designs will work and just run slower if you drop the voltage, some will burn up. If you are using DC contactor coils, you want to install a diode across the coil with it reversed, so during normal operation, there is no current flow (i.e., it is blocking the flow and not acting like a short across the relay coil - IOW, put the cathode on the plus side of the coil and the anode on the minus side). Then, when it is de-energized, the coil's induced voltage will be drained off, and not cause the thing to chatter as the spike decays. If the coil is big enough, there can be enough current generated when control power is removed to cause it to momentarily re-energize itself. the diode prevents that and lenghtens the life of the relay contacts for minimial costs.