Manual 35018V1
505XT Digital Control System for Steam Turbines
Woodward
98
Figure 3-22. Typical Extraction Steam Map
Admission Only Steam Map
Before a turbine’s admission steam map can be programmed into the control, it must have the
intersection points A, B, & C (refer to Figure 4-5).
If points A & B already exist, the only conversion necessary is the extension of the LP=100 line and the
P=100 line until they cross or intersect (this is Point C for programming).
If only point A exists, your map will have to be modified to include points B & C. The LP=0 line will need to
be created. To create the LP=0 line you must know the minimum required steam flow through the back-
end of the turbine. In our example steam map (Figure 4-5) the minimum required flow was 10 000 lb/h
(4536 kg/h).
1. Extend the zero admission (or induction) line (p=100%). Refer to Figure 4-5.
2. Find your turbine’s minimum back-end steam flow (this will be point B’s HP flow).
3. Mark the intersection of the zero admission line and the turbine’s minimum back-end (cooling) steam
flow. This mark will be Point B for programming.