Woodward 505XT, Инструкция по установке и эксплуатации, Страница: 119 / 242

Manual 35018V1 505XT Digital Control System for Steam Turbines
Woodward 117
Optionally a relay can be programmed to indicate when Local mode is selected (energizes when the
Local mode is selected). There is also indication of the Local/Remote mode selection through Modbus
(address = true when the Remote mode is selected and false = when the Local mode is selected).
The 505 is defaulted to only allow control operation though its front panel when the Local mode is
selected. If desired, this defaulted functionality can be changed through the 505’s Service mode. The 505
can be modified to also allow operation through contacts inputs, or Modbus port #1 or Modbus port #2
when the Local mode is selected.
All pertinent local/remote control parameters are available through the Modbus links. See Chapter 6 for a
complete listing of all Modbus parameters.
Relays
The 505 has eight relay outputs available. The first of these relays is dedicated for a system shutdown
command from the 505. The second relay is fully configurable, but is defaulted for an alarm indication.
The other six relays can be programmed for a variety of indications, and system functions.
For fail-safe operation, the dedicated Shutdown relay is energized during normal system operation, and
will de-energize when a shutdown occurs.
The dedicated Alarm relay is normally de-energized. This relay will energize upon an alarm condition and
stay energized until the alarm condition is cleared. Optionally this relay can be configured, through the
505’s Service mode, to toggle on and off repeatedly when an alarm conditions has occurred. With this
configuration if a reset command is given and the alarm condition still exists, the relay will stop toggling
and stay energized. The relay will start toggling again, upon a new alarm condition. This option can be
used to inform the operator when another alarm condition has occurred.
Any of the configurable relays can be programmed to function as a level switch or mode indication. When
programmed as a level switch the relay will change state when the selected parameter reaches the
programmed level (energizes when value is higher the programmed level).
Relay Functional Clarifications
The Shutdown Condition relay may be programmed to indicate a shutdown condition on a remote panel
or to a plant DCS. The Shutdown Indication relay is normally de-energized. This relay will energize upon
any shutdown condition and stay energized until all trips have been cleared. The ‘RESET CLEARS TRIP’
function has no effect on the programmable Shutdown Indication relay.
When programmed as a Trip relay, the respective relay will function like the dedicated “Shutdown” relay
(normally energized and de-energizes on a shutdown) to indicate the position of the dedicated Shutdown
relay. This relay output can be programmed to indicate a 505 initiated trip by setting the ‘Ext trips in Trip
Relay’ option to NO. Using this option, 505 trip annunciation will only occur if the 505 tripped the turbine
and not annunciate when the other external devices shuts down the unit (external trips).
The Alarm Condition relay may be programmed to indicate an alarm condition on a remote control panel
or to a DCS. The Alarm Indication relay is normally de- energized. This relay will energize upon any alarm
condition and stay energized until all alarms have been cleared. If the ‘BLINK ALARMS’ option is ‘YES’
the programmable Alarm Condition relay will toggle on and off repeatedly when an alarm condition has
occurred. With this configuration if a reset command is given and the alarm condition still exists, the relay
will stop toggling and stay energized.
The 505 Control Status OK relay is normally energized, and will only de-energize if unit inlet power is lost,
the 505’s CPU fails, or the 505 is in the Configuration mode.
The Overspeed Test Enable relay will energize when an Overspeed Test is performed. This relay
functions like the 505 OSPD key’s LED (it repeatedly toggles on and off when turbine speed is above the
turbine Overspeed trip setting).