Woodward 505XT, Installation And Operation Manual, Page: 62 / 242

Manual 35018V1 505XT Digital Control System for Steam Turbines
Woodward 60
IDLE 2 SETPT = 1500 RPM
USE IDLE 3 = *TRUE
RATE TO IDLE 3 (COLD) = 5 RPM/S
RATE TO IDLE 3 (HOT) = 15 RPM/S
IDLE 3 SETPT = 2000 RPM
IDLE 3 DELAY TIME (COLD) = 30 MINIMUM
IDLE 3 DELAY TIME (HOT) = 20 MINIMUM
RATE TO RATED (COLD) = 10 RPM/S
RATE TO RATED (HOT) = 20 RPM/S
RATED SETPT = 3400 RPM
Table 3-2. Hot And Cold Parameter Interpolation rates and delays
(Viewed in the Service Mode, see Volume 2)
LOW IDLE DELAY = 20 MINIMUM
RATE TO IDLE 2 = 10 RPM/S
IDLE 2 DELAY = 10 MINIMUM
RATE TO IDLE 3 = 10 RPM/S
IDLE 3 DELAY = 10 MINIMUM
RATE TO RATED = 15 RPM/S
RST Timer Level = 3500 RPM
Hot RST Timer (min) = 10 MINUTES
Based on the example’s configuration and trip time:

The Speed Set Point would ramp to 1000 rpm at the rate to minimum setting and hold for 20 minutes
(turbine speed must also be at or above 1000 rpm)

Move to 1500 rpm at 10 rpm/s and hold there for 10 minutes

Move to 2000 rpm at 10 rpm/s and hold there for 10 minutes and lastly

Move to 3400 rpm at 15 rpm/s. At 3400 rpm, the sequence would be completed

However, speed reference must be above the HOT RESET LEVEL during more than HOT RESET
DELAY, to fully use the HOT parameter

If the unit was tripped for 2 hours or less and restarted, the control would use the hot start
parameters. If the unit was tripped for 22 hours or longer and restarted, the control would use the cold
start parameters.
The 505 will automatically set the hours-since-trip timer to its
maximum setting of 200 hours to ensure a cold start is selected after
a power up or upon exiting the Configuration mode. The hours-since-
trip timer will reset only when the turbine speed has increased above
the minimum governor speed/RST timer level setting for the Not RST
timer duration.
Optionally, if a contact input is configured for the “Select Hot Start” function, then the Auto Start
Sequence’s Hot start setting will be selected and used during the start routine when the respective
contact is closed, and the Cold start curves will be used when the respective contact is open.
Hot/Cold Starts with NO Interpolation between the curves
If it is desired to have the control NOT interpolate between the Cold/Hot ramp times, then the
Cold Start
and
Hot Start
hour settings can be set equal to each other and no DI input is needed (the Cold and Hot
Start hours setting is found in
Configuration/Turbine Start menu
). The unit will follow the Hot times
below this setting and the Cold Values when this time is exceeded.