The industry standard for commercial door hardware is DC voltage, either 12 or 24 volt.
Beware of product operating on other voltages.
You will not be able to mix and match products as needed, but instead
be tied to some proprietary system.
Current running throught a building is AC ''pulsating'' power.
If you could hear that power it would be like a very fast clicking noise.
Commercial hardware likes the clean, smooth power that comes with DC.
It would sound like a long, continuous tone.
Rectifiers convert pulsating power to continuous power.