Shutdown And Alarm Function Summary; Valve Ramp (Limiter) Control - Woodward Peak 200 Original Instructions Manual

Manual 35051
Before the Remote Speed Setpoint mode can be enabled, the following operating conditions must be
met:

The turbine speed must be above the MIN GOV SPEED.

The REMOTE SPEED ENABLE input must be closed.

The Remote Speed Setpoint signal must be between 2 mA and 22 mA.
With the IDLE / MIN GOV input closed, and the turbine speed above MIN GOV SPEED, when the
REMOTE SPEED ENABLE input is closed, the ACTUAL SPEED SETPT will ramp from the current speed
to the REMOTE SPEED SET input at the REMOTE-NOT-MATCHED RATE.
The Remote Speed Set Point may be in one of the following states (message status is found on the
remote speed setpoint pop-up screen):

Disabled—The remote set point function is not enabled and will have no effect on the speed set
point.

Enabled—The remote set point has been enabled.

Active—The remote set point is in control of the Speed set point but the speed PID is not in control of
the actuator output.

In Control—The remote set point is in control of the Speed set point and the speed PID is in control
of the actuator output.

Inhibited— The remote set point cannot be enabled. The input signal has failed, the unit is shut
down, or remote set point is not programmed.
The Peak200 will stay in the remote speed setpoint mode unless one of the following occurs:

The REMOTE SPEED ENABLE input is opened, or a disable command is given from the front panel
or Modbus.

SPEED is reduced to below MIN GOV SPEED.

A SHUTDOWN occurs.

A REMOTE INPUT FAILURE occurs. The ACTUAL SPEED SETPT will be the value of the REMOTE
SPEED SETTING input at the time when a REMOTE SPEED SET failure is detected.


Shutdown and Alarm Function Summary

A shutdown condition is signaled by the TRIP relay which defaults as DE-ENERGIZE on trip. It can be
configured to ENERGIZE on trip by checking the Invert Logic box on the Configuration / Relay Output 01
screen.
Alarm conditions are signaled by the ALARM relay energizing when an alarm is present. It can be
configured to de-energize on alarm by checking the Invert Logic box on the Configuration / Relay Output
02 screen.
The TRIP and ALARM functions latch. A RESET is required once the condition is corrected to clear the
latch. If the governor is TRIPPED, a RESET command will clear the TRIP RELAY output and the front
panel TRIPPED LED if configured for RESET CLEARS TRIP = TRUE. This does not clear the TRIP input
on discrete input channel 3, which may be a part of the turbine trip string. When an operator resets this
string, the turbine is ready to start. (If an EXTERNAL TRIP still exists, the control will not initiate a start).
Either the output of the VALVE RAMP or the SPEED CONTROL is used to open and close the steam
valve during turbine operation. These outputs are LOW SIGNAL SELECTED by the LSS Bus so that the
control function with the lowest demand sets the position of the actuator.
The VALVE RAMP is opened via the START COMMAND during START UP to run its output out of the
way of the SPEED CONTROL (100%-Open). When the control gets a TRIP command, the VALVE RAMP
over rides the SPEED CONTROL and closes the ACTUATOR (0%-Closed).
The SPEED CONTROL increases or decreases the steam demand signal during normal turbine
operation.
Woodward
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Valve Ramp (Limiter) Control

Peak®200 Digital Control for Steam Turbines
108