Understanding HOA (Hand-Off-Auto) switch

 

As we’ll see, perhaps the confusion is in the use of the term “HOA” itself. One of the best ways to determine how to designate a control switch operation is to use the terms “Location of Control” and “Mode of Control.”

 

Location of Control is a phrase that refers to the place from which the motor or other field device is being operated. Locations could include “Hand” (it is operated directly at the starter), “Local” (it is operated by Start/Stop contacts near the motor), or “Remote” (it is operated by a PLC or other device that is distant from the process itself) and “Off” (no location allowed).

 

Location of Control은 motor 등 기기가 제어되는 위치를 의미한다.

"Hand" (스타터에서 직접 작동),

"Local" (모터 근처의 start/stop 접점으로 작동)

"Remote" (PLC 등)

"Off" (위치가 허용되지 않음)

 

 

https://www.scadaware.com/blog/understanding-hoas-to-avoid-confusion-for-plant-personel/