Woodward 505XT, Инструкция по установке и эксплуатации, Страница: 87 / 242

Manual 35018V1 505XT Digital Control System for Steam Turbines
Woodward 85
Auxiliary as a Limiter (not using Enable/Disable)
When configured as a limiter, the Auxiliary control is low signal selected (LSS) with all of the other PIDs,
allowing it to limit turbine speed/load based on any auxiliary parameter which is directly related. To
configure the Auxiliary controller to function as a limiter, do NOT check the configuration parameter of
‘Use Aux as Controller’.
When Auxiliary is configured to act as a limiter the Auxiliary PID will ‘limit’ the LSS bus when the input
reaches the set point. The Aux set point initializes to the programmed ‘Setpoint Initial Value’ setting on a
power-up-reset. This set point may be adjusted at any time and will remain at a setting (running or
shutdown), provided a power-up-reset did not occur.
Depending on configuration and system conditions, the Auxiliary Limiter may be in one of the following
states (505 front panel screen messages):

Auxiliary is Enabled - Auxiliary has been enabled but the generator and utility tie breaker permissives
have not been met (generator applications only).

Aux Active/Not Lmting - Auxiliary is configured as a limiter but is not limiting the LSS bus.

Aux Active w/Rmt Setpt - Auxiliary is not in control of the LSS bus and the remote Auxiliary input is in
command of the set point.

Aux Control w/Rmt Setpt - Auxiliary is in limiting the LSS bus and the remote Auxiliary analog input is
in command of the set point.

Auxiliary is Inhibited - Auxiliary cannot be enabled. The input signal has failed.
For generator applications, Auxiliary control limiting can be configured to be disabled when the generator
and/or utility tie breakers are open. Program settings ‘Generator Breaker Open Aux Disable’ and ‘Tie
Breaker Open Aux Disable’ may be configured to deactivate Auxiliary PID limiting, depending on system
breaker positions. When both settings are programmed as unchecked (NO), the Auxiliary limiter will
always stay ‘active’. If either setting is programmed as checked (YES), the Auxiliary limiter will be active
only when the tie breaker or generator breaker respectively, is closed.
If the unit is not configured for a generator application, the utility tie and generator breaker inputs do not
affect Auxiliary limiter status, and the Limiter will be active at all times.
Auxiliary as a Controller (using Enable/Disable)
When configured as a controller, the Auxiliary PID may enabled and disabled on command. With this
configuration, when Auxiliary control is enabled it instantly takes full control of the LSS bus, and the
Speed PID is switched to a tracking mode. When Auxiliary control is disabled, the Speed PID instantly
takes full control of the LSS bus. To allow a bumpless transfer between modes, when the Auxiliary PID is
enabled, the Speed PID tracks a few % above the Auxiliary PID’s LSS bus signal. When the Auxiliary PID
is disabled, its set point tracks the Auxiliary PID’s process signal.
To configure the Auxiliary controller to function as a controller, check the configuration box ‘Use Aux as
Controller’ on the Auxiliary Control configuration page.
The Speed PID will only track the Auxiliary PID LSS bus signal up to 100% speed/load. Thus if turbine
speed/load reaches 100%, the Speed PID will protect the unit by limiting unit speed/load to less than or
equal to 100%.
Depending on the configuration and system conditions, the Auxiliary PID may be in one of the following
states (505 front panel screen messages):

Auxiliary is Disabled - Auxiliary is disabled and will have no effect on the LSS bus.

Auxiliary is Enabled - Auxiliary has been enabled but the generator and utility tie breaker permissives
have not been met (generator applications only).

Aux Active/Not in Ctrl - Auxiliary has been enabled, permissives met, but is not in control of the LSS
bus.

Aux Active w/Rmt Setpt - Auxiliary has been enabled but is not in control of the LSS bus and the
remote Auxiliary input is controlling the set point.

Auxiliary in Control - Auxiliary is in control of the LSS bus.