In multi-valve turbine inlets, partial arc ad MISSION allows the steam to ENTER per valve opening in a sequential manner, so as load is increased, more valves open to admit steam. This can cause uneven HEATING on the high-pressure annulus as the valves are individually opened with load increase. In full-arc ADMISSION, all regulating valves open but only at a percentage of their full opening. With load increase, they all open more fully. This provides more uniform heating AROUND the high-pressure part of the turbine. Most modern controls start with full-arc and switch to partial arc to reduce throttling losses through the valves.

In multi-valve turbine inlets, partial arc ad mission allows the steam to enter per valve opening in a sequential manner, so as load is increased, more valves open to admit steam. This can cause uneven heating on the high-pressure annulus as the valves are individually opened with load increase. In full-arc admission, all regulating valves open but only at a percentage of their full opening. With load increase, they all open more fully. This provides more uniform heating around the high-pressure part of the turbine. Most modern controls start with full-arc and switch to partial arc to reduce throttling losses through the valves.