[Tasker] Woodward 505 LST [Tech Support Index]

Woodward 505 LST
Initial Product Questions during Tasker/Peaker's first 505 LST installation
Related to Type 3 for use at WPS Weston 2

List Started in 2008 and Partially Updated on 3/20/09 (resolved questions)
2010 note, Scott Taylor was Tom Truax's initial main contact for the 505 LST, but Scott is no longer with Woodward as of 9/2010.

Open Questions  (response in blue) follow up question (in red)
Contact Tom Truax (805 680-7727 cell) if username and password are needed to access any protected links

No open Question:  All questions resolved

Resolved Questions
Updated 4/1/09

• How do we confirm the Target Go To Value?  Do we read the analog write registers?
  • Scott's Answer was: The analog write registers are mirrored at analog read registers
    • 4:0005 Speed Setpoint to 3:0038
• We need to confirm which register to use to track the VPC demand upstream of the Actuator Linearization Table (left control valve curve). We were initially reading the actual actuator output signal from AO:4 on register 3:0016, but since we adjusted the actuator linearization table, the 505 made a large unintended step change after breaker closure when the control switched into coordinated mode. The customer's DCS tracks the 505 valve output to achieve a bump less transfer 10 seconds after breaker closure, but I suspect what is happening is that customer's 4-20 mA signal for coordinated VPC control is input to the 505 LST upstream of 505's actuator linearization table, but the customer's DCS / PLC is tracking the actual output value which is downstream of the table. I told the customer's DCS engineer to switch from tracking the actual output to tracking the VPC Demand at 3:0045. I suspect this value is upstream of the actuator linearization table, but I need to confirm. I also need to know what the VPC demand register 3:0045 will read when not in VPC control.
  • Modbus value 3:0045 shows the VPC demand (x10) (with any frequency participation bias added). The frequency bias logic adds some complexity to this and there is some additional logic that I do not clearly understand but I believe this should track the LSS value when not in VPC control. It would be best to check this to confirm what is does while not in VPC control. For tracking VPC demand, this should be a good value to use.
• Comm Ports; is only one used for control?
  • Phone Conference on 11/21/08 
  • One is labeled DCS and the other is labeled HMI.  What is the difference?
    • Walter Grassens 9/17- As far as the Modbus addresses go, there is no difference between the two blocks with the exception of the Throttle Pressure Input for Throttle Pressure Control.  If Throttle Pressure Control is used, the pressure input comes from the DCS port 4:0002 (this address is not connected on the HMI port).  If this port is not used, it will come from Analog Input 5. The HMI port should be used by the control computer where as the DCS port is meant for a plant-wide control computer, which is usually slower but could perform the same functions as the HMI computer.
      • 11/11 Clarification:  If TPC is used, it must receive the value from Analog Input 5 because the Modbus update may be too slow for reliable PID control.  The value can be received via Modbus for breaker closure throttle scheduling because this functionality is not a time critical PID function.
  • What does the Discrete input 15 on terminal 26 (DCS in Control) do?
    • Walter Grassens - Discrete Input #15, pin 26, is simply a status indication.  This DI15 input is tied directly to a Boolean Read, 1:0057, on both ports (DCS and HMI) and a Service Mode status indication.
• What conditions must be present to clear a Comm Port Fail Alarm
  • There are two Comm port alarms, Alarm – Comm Port 1 Failed, is for the DCS comm. Port, Alarm - Comm Port 2 Failed, is for the HMI com port.
  • The alarms are disabled if the port is not configured. If configured, the alarm is connected to the Link Error on the associated MODBUS_S.
  • The alarm latches but there is no reset required to get communications working. As soon as communications are working the link error should clear and it will be possible to reset the alarm. There should be no need to reset the control.
  • The Modbus block has more diagnostic information (exception error indications, error percentage, and error numbers) that is accessible from the debug mode. I can help you access this when you are at site. This may provide more clues as to why the link error is occurring.
• If Raise and Lower are both high, the the lower command will have priority.  If the lower command is released while both are still high, the raise will become active. (testing on 3/20/09)
• Note: sometimes when the control does not display a menu, pressing the clear key will unfreeze the control.
• Ramp rates on trip.  Manual says they go to slow rate, but Gap Logic says the only go to slow on power up.
  • Confirmed that the rate will not change on trip, but will default to the slow rate after entering and exiting the program mode.
• Is the valve rate limited in Coordinated VPC control once the setpoint has ramped to match the remote 4-20 mA input signal?
  • Manual 26440 page 66 (top) indicates that the rate is limited by the selected rate when the mode is enabled, but what is not clarified is weather the rate limitation only applies during the initial ramp to match the setpoint to the remote signal, or is the rate always in effect when in Coordinated VPC control mode?
  • The valve continues to be rate limited by the selected VPC rate in Coordinated Control, even after the setpoint is reached.
• Valve limiter / go and hold / If the control is started in auto with a go command, the valve limiter will begin to ramp open.  If a hold command is issued, the speed setpoint ramp will stop, but the limiter ramp will continue toward 100%.  A raise or lower command will drop the control into manual and stop the valve limiter.  The limiter ramp can be restarted by placing the control back into auto and giving a go command.
• Go Command and Coordinated Control.  Coordinated control does not use the go command.  Upon switching into Coordinated Control the 505 will ramp toward the 4-20 mA value at the selected rate (slow, medium, fast)
  • Note that manual 26440 page 66 indicates that after a the control is placed in Coordinated Mode, the Go command must be given to ramp toward the Coordinated 4-20 mA setpoint.  The manual is wrong.  A go command is not required for Coordinated Control
• Throttle Pressure Control.  Do we need to configure it even if we aren't going to use it for TPC except to accept minimum load?  Yes, if you want to use the analog input for TP, TPC must be configured, but the setpoint can be moved out of the way so it will never enable.
• What does the enable alarm screen or enable trip screen config option do?
  • Will a Modbus reset reset trips via one command.  No, On the keypad, the trip screen must be accessed to clear a trips and the alarm menu must be accessed to clear alarms.  With Mobbus there are also separate registers to reset for trip items and alarm items
• What is the mpu fail speed on the way up and the way down?
  • Scott reports the code indicates it is 100 RPM on the way down, and arm on the way up at 200 RPM
  • Testing at WPS W2 indicated it is 200 RPM either direction.
• Valve Limiter start ramp.  Should it move up out of the way at a fast rate after start? manual 26440 page 64. No, the manual is wrong.  You can move it out of the way faster manually, but automatically, it will continue ramping toward 100% at the start rate otherwise.
• When testing VPC Coordinated Control / Seems to delay on enable? No Delay, but droop may have an effect when testing open loop. Do we need to press the Go button? No
• Valve position inputs: Can we read the values even if they are turned off? Yes
• 3/2009 How do you change the Modbus address
  • Adjust in the De-Bug mode
    • Gap Modbus blocks and how to get into the De-Bug Mode
    • This same general location also had the comm time out value, changed from the default of 3 seconds to 10 seconds
    • From Scott Taylor: You are correct about some values being accessible only from DEBUG. I don’t know the best way to inform uses about these options. In other controls we do have some special functions that would not be required by most users that are only accessible by Debug. We don’t want to complicate configuration for the majority of users but we do include some special functions that are available with “help” from Woodward.
       
• 3/2009 The customer prefers to do the valve raise / lower for pre-warm over hardwired discrete inputs because they send pulses and their network is slow. We need to confirm that we can do the pre-warm valve control raise / lower via the contact inputs on terminals 14 and 15.
  • Verbal response from Scott Taylor indicates that the hardwired contact inputs cannot be used for pre-warm VPC.  Scott's email response was:
  • Looking at the code for the Prewarm. It can be enabled / disabled from modbus through BW14 (if REMOTE mode is true – I believe this is consistent for all modbus commands). When enabled a manual ramp is used to stroke the TV. This can be controlled in LOCAL from the keypad or in REMOTE the open command it from BW30 and the close command is from BW29
  • Also note that the manual is incorrect.  Pre-Warm controls the throttle valve, not the governor valve, so for a type 3 configuration pre-warm won't do anything because there is no throttle valve.
     
• 3/2009  MW Scaling: The speed values are scaled 1 to 1, and the valve position values are scaled 10 to 1 to yield resolution to 1 decimal place. Our question is the MW write value to register 4:0001. I would suspect that is also scale 10 to 1, but we would like to confirm. There is no listing of the scaling in the manual.
  • In the manual, pg 114, Addr: 4:0001 is described as DCS MW VALUE this should be HI INPUT CONTACT LIMITER (x10) (>NOTE: would you call this x10 or /10?)  3:00042 is described as LSS it should be CONACTINPUT LMT L (x10) These limits apply to the VPC reference when the hardwired raise and lower commands (BI 3 and 4 which are on TB 14 and 15, respectively) are used.
  • Summary, there is no MW input to the 505.
• Modbus Address 1:0010 / Go / What does this indicate.  Does it indicate that the control is ramping? or does in indicate that the Modbus input is high?  The description is also duplicated at address 1:0098.  What is the difference?  I could not find a read register to indicate "hold".  Is hold the opposite of Go?  If the go read is not high, can we assume that "hold" is active?
  • Scott Taylor (11/24/08) - 1:0010 is tied to the GO latch. 1:0098 is tied to the GO_RATED block which is true if the GO latch is true, the unit is OFFLINE, the mode is AUTO, and both the speed and the speed reference are above the LO_IDLE setpoint.
  • Scott Taylor (24/11/08) - while the GO latch is true 1:0010 either the speed ref or VPC ref should be moving.
  • Scott Taylor (24/11/08) - All HOLD conditions reset the GO latch but as you mention there is not a specific HOLD indication. It is not exactly correct to say the not going is holding – if the setpoint is achieve we are not going but I would not necessarily call that a hold. You would have to do some more complicated logic to separate a HOLD state (depending on how you define it).
• Does the Go Command toggle to hold when the mode changes?  Example, if in Semi-Auto or Coordinated Mode, and the Manual is selected, then Semi-Auto is selected again, will the go command need to be reissued or will the control begin ramping toward the target?
  • Scott Taylor (11/24/08) - The GO latch is reset a one-shot from modes AUTO, SEMI, COORD, or by the Manual mode (so any change of modes generates a Not GO (Hold) condition. Also STOP, TRIP, Gen Bkr closure, or reaching selected setpoints reset the GO latch.
• What does the go command do when a setpoint is achieved?  Will the control toggle to hold upon completing a ramp to a setpoint or will the go command stay active so that when the setpoint is changed again the control will ramp toward the new setpoint?
  • Scott Taylor (11/24/08) - As mentioned above, when a setpoint is achieved the GO latch is reset.
• If the Semi-Auto Target setpoint is changed in the middle of a ramp, will the ramp continue toward the new setpoint?  Will it drop out of Semi-Auto Mode?
  • Scott Taylor (11/24/08)  The setpoint is sampled when RUN/GO is selected so changing the setpoint will not affect the original target.
• I'm still not clear on the TV (Throttle Valve) position error trip (address 1:0141)  Does this mean that the 505 will trip if the analog position input for the Throttle (Stop) valve does not agree with the demand).  I suspect this may be a non-issue with a type 3 valve arrangement because we don't modulate the throttle valves.  There is also an analog input for governor valve position.  It is my understanding that that value is for info only and the unit will not trip if it does not match the demand.
  • Scott Taylor (11/24/08) - 2 second after a shutdown and for the reset delay (configurable but defaulted to 100 seconds) after the shutdown is cleared, if the TV is not closed a trip is issued. This prevents resetting if the TV is not closed.  TV “not closed” is based on DI7 and/or DI8 if limit switches are selected or analog inputs AI2 and AI4 (type 1) being greater than *2.0 if they are configured.  NOTE: if the Analog position indications are configured and the inputs are failed this is also considered a “not closed condition”.  NOTE: This is not a position error trip – it is only enabled when the turbine is already tripped by something else.
  • Scott Taylor (11/24/08) - For the Governor Valves there is only the GV not closed alarms 1:0037 and 1:0032 if the demand is < *2.0 and the feedback is not < *2.0. As we discussed the text message for valves 1 and 3 are switched (505 display).
• Modbus Trip indication reads seem to be duplicated in register rages 1:0001-09 & 1:0131-139.  Is there any difference?
  • Scott Taylor (11/24/08) - No difference between the signals in the range 1:0001-09 & 1:0131-139. I’m not sure why these are replicated and 140 and 141 are not.
  • What is the difference between address 1:0140 and 1:0133 or 1:0134?  I understand 133 & 134, but not 140.
    • Scott Taylor (11/24/08) 140 – EXTERNAL EMERGENCY TRIP – this is generated if contact input DI1 is OPEN. 133 is the Red E-Stop button on the 505 keypad and 134 is DI16 (the trip with the override functions that we discussed previously as being designed to work with the trip oil header pressure).
    • Note: to read the shutdown state, use register 1:0060 which is the state of the shutdown relay.  A 1 will indicate not shutdown, and a 0 will indicate shutdown.  It follows the state of the trip output relay.
• Does the actuator output go to 0 mA on shutdown or 4 mA.  Note that the 505 LST actuator outputs are not on the standard 505 hardware actuator outputs, they are on the analog readouts.  We need to know because the customer wants to implement a last position lock on their actuator so it maintains the last position if the demand signal goes below 2.5 mA.
  • Phone Conference on 11/21/08  The hardware actuator outputs go to zero, but since we are using a readout for the actuator, the configured actuator output will only go to 4 mA on shutdown.  Scott's confidence is high so we do not need to check further.  On testing at WPS W2, it was noted that the output goes slightly below 4 mA, but not down to zero.
• For one shot inputs like Go/Run or Select-Semi Auto, do we write the value high one time and leave it high, leaving it up to the 505 to toggle it back to 0, or do we do the one shot with the HMI and write it high for 1 second and then write it back to zero?
  • Phone Conference on 11/21/08  We do a One Shot.  Write it high and then write it back to zero.  The 505 looks for a change of state from low to high.
• On a rolling start, how does the valve limiter behave?  Will it ramp from zero at the selected rate?  The speed setpoint will match the actual rolling speed at the time of the run command, but if the valve limiter is slow to open, speed will continue to decay for some time.
  • Phone Conference on 11/21/08 Scott suspects it behaves like a regular 505.  The limiter will go to zero and need to ramp up to the value to support the current speed at the start ramp rate, which is a fixed value (but tunable in the service mode).
• The Modbus list throttle valve position error trip.  What is the underlying logic? is it tunable? Is it looking at the feedback, or just an open loop on the output?
  • Phone Conference on 11/21/08 Scott suspects it behaves like a regular 505.  The limiter will go to zero and need to ramp up to the value to support the current speed at the start ramp rate, which is a fixed value (but tunable in the service mode).
  • This behavior has not been clarified.  It was noted during testing, but the logic sequence was not definitively determined.  During testing at W2 It seemed to occur from the front panel when the valve position reached 100% but the valve position feedback was zero.  After switching off the feedback and the other valve inputs, the trip or message did not occur again. 
• How does the DCS confirm communication is OK.  Is there a watchdog bit?  Can we write to a spare register and then read the register?  Is there a register we can write to and then read the result on another read register?
  • Phone Conference on 11/21/08 The 505 has it's watchdog timer, but there is no echo register.  We should be able to toggle to a spare register and then read the value back from the same register.  The spare registers should respond to the Modbus commands for read and write.
• Clarification on Trip Indication?
  • 1:0058 / DI:16.  This is listed as Go in manual 26440 Page 111.  I suspect it should follow the revised input for that terminal? Manual needs correction?
    • Noted in Phone conference on 11/21/08.
• What does the discrete input #16 on terminal 27 do?  The old manual 26173 shows it as a Go / Run command, but the newer manual 26440 shows it as external trip with override.  What does that mean?  Does it need to by high or low for run?  Where did the old Go / Run command go?
  • 11/11/08 – Intended to be used for loss of trip oil shutdown.  Any reset will override the shutdown for 100 seconds (adjustable in the service mode or configure mode).  When the input goes high, it triggers a one shot internal reset.  The input must be high to run (except for the  override timer).  The external trip on DI:1 is not tied to the override logic, so if an override is needed to break a tirp logic loop, then the DI:16 input must me used.
  • Don not know what happened to the Go Run DI.  Go now needs to be accomplished via the keypad or Modbus.
    • No.  Go / Run functionality is not available only from the 505 keypad or over the Modbus Comm Link
• How do you enter and go to a Modbus Setpoint?
  • 11/11/08
    • Control Mode:  Refers to 2 concepts
      • Speed, VPC, or TPC
      • Manual, Semi-Auto, Auto, Coordinated
    • A Modbus setpoint is sent via an Analog Write
    • The Semi Auto Mode Must be Selected (Modbus Boolan Write 0:0011)
      • Control mode is universal across Speed & VPC modes. Semi Auto only applies to Speed and VPC.  It is not applicable to TPC or Valve Limiter
      • Mode selection is via a one shot, so it is looking for a change of state
      • Note, Auto Control will have no effect on-line.  Auto and Semi-Auto can both be configure.  They are not mutually exclusive.  Auto will use only 2 targets, idle and rated, and can be utilized from either the keypad or over the Modbus Comm Link.  Semi-Auto permits any setpoint to be entered.  You can select Semi-Auto via Modbus or the front keypad, but you cannot enter or display the target setpoint via the keypad.  The target setpoint can only be entered and displayed over Modbus.
    • A go to command is issued
    • A hold command will stop a ramp and but leave the mode unchanged
    • A raise or lower command will cause a ramp to stop and change the mode to manual mode
      • Note that the manual is incorrect regarding this logic.  The manual indicates that a raise/lower input will hold a ramp, but leave the control mode unchanged.  To confirm, a raise/lower input will cause the control mode to revert to manual mode.
    • Do not read the mode via the discrete inputs because they are one shot.  Read the mode from 1:0078, 79, 80 & 119
    • Start Sequence:
      • It should be noted that on start, the speed setpoint will track the actual speed down to zero.  If a start is initiated with the turbine rolling, the speed reference with be at the rolling speed.
      • The desired control mode needs to be selected.  If a Go/Run command is received with the control in manual mode, the valve limiter will ramp open but the speed setpoint will remain at zero, so the valve will not actually open.
      • The Rates are not defaulted back to zero on trip, so the desired rate needs to be selected
        • Note that the manual is incorrect regarding this logic.  The manual states that the rates will default back to the slow rate on trip, but the GAP shows the rate defaulting to slow only on power-up, not on trip.
  • How do we confirm the Target Go To Value?  Do we read the analog write registers?
    • The analog write registers are mirrored at analog read registers
      • 4:0005 Speed Setpoint to 3:0038
      • 4:0003 Valve Position Setpoint 3:0044
      • These registers display the target, not the actual setpoint
        • The actual speed reference is displayed at 3:0029
        • The actual valve position demand is at 3:0045 (actual output downstream of all bias and scaling)
    • Also note VPC Service Mode terminology
      • VPC Reference is the instantaneous output from the Ramp block (not the target).  This value is upstream of any bias from the speed regulation or the linearization table
      • VPC Demand is the actual output downstream of all bias and scaling)
      • VPC Target is the target value by the DCS input
      • DCS Demand refers to the 4-20 mA demand input value from the DCS (not the DCS Modbus value).
• Do we need to use the inputs for valve position?  What are the consequences of not configuring?
  • Reading of the manual seems to indicate that the control may function, but will there will be an alarm if the valves are not open or closed depending on the operating mode, running or shutdown?  There is no trip indication for the valves, but it is not clear if there is a start permissive, or what other logic (other than alarming ) might be affected.
  • The valve position inputs, analog or discrete, are optional and do not need to be wired if valve testing is not utilized.  There are no permissive tied to the valve position outside the scope of valve testing.  There may be an advantage of having the position input because it will then be available over the Modbus Comm Link.
  • If valve position input is not desired, then the config blocks can be set to no.  If the inputs are routed to the 505, but not used, then the values should still be available over Modbus.
• Does the PID equation have an adjustable Derivative Value?
  • Yes.  The DR is displayed and adjustable from the dynamics menu.  You do not need to be in the service mode to adjust the DR.  The DR is not specified in the configure mode.  It is defaulted to 100
• Rate Selection
  • When selecting Slow, Medium, or Fast Rates via Modbus, does the selection pertain to all ramps?  Speed, Valve Position, and Valve Limiter?
    • Scott Taylor 9/17 – The same selection is applied to Speed and Valve Position ramps when the operator can specify a rate.  There are cases where predetermined, and sometimes instantaneous, rates are used based on operational state (as Walter has described).
    • Walter Grassens - The Speed and Valve Position ramps are affected by this Modbus selection.  The valve limiter is explained in response to the question below.
  • If a rate is selected for the speed ramp, and the breaker closes, is the same rate selected for the valve position control ramp, or is it defaulted to the slow rate on breaker close?
    • Scott Taylor 9/17 –  The same operator selected rate remains effective.  There is a load step on breaker closure but this does not affect the rate selection.
    • 11/11 Note:  The only thing that will automatically change the speed rate is a power down, otherwise the rate remains as selected
  • How do you select which ramp rate is used for the valve limiter?  The manual does not detail what is in the valve limiter menu. Reference Manual 26440 Pg 59 & 77.
    • 11/11 The Valve Limiter ramp rate is not user selectable.  It is determined by logic based on whether the system is starting (Start Rate) or when speed is in control of the LSS including during a shutdown when speed demand is switched to ‘0’, the fast rate will be used. Otherwise the Valve Limiter ramp will use the Normal rate (Medium) as a default.  The rates are tunable in the service mode
      • Note: the Modbus output for valve limiter rate will not display the correct valve.  The GAP block is based on incorrect logic (bug).
    • As noted by Walter, the normal rate for the valve limiter is the medium rate, so if fine resolution is desired, then the medium rate should be set to a low value.  For example, if the valve limiter will be used for pre-warm then set the medium rate to about 5% per minutes to achieve fine resolution of the valve position.
• 10/18/08 The 505 LST terminal figure for a Type 3 configuration in the old manual 26173 shows a different physical layout than the newer manual 26440.  The old manual shows the actuators connected to the actuator output drivers, but the same terminal block figure in the newer manual shows the Actuator drivers being used as readouts.  I need to confirm that we connecting the actuator to analog output 4, and not the terminal labeled actuator output.  According to the 505 manual, the readouts (now driving the actuator?) are a different electrical spec than the actuator drivers (now driving readouts?).  What was the reason for the swap?  The readouts can drive 600 ohms, but the actuator drivers can only drive 360 ohms?
  • Nevil Brake - 10/28 – I have been advised that manual 26440 Rev A (Attached) is the most current manual and should be followed – I do not know the reasons for the change or have access to schematic diagrams.
  • Tom Truax notes:  The actuator driver goes to zero on trip, but the analog readouts do not, so that might be a motivation factor since some actuators will fault if the drive signal is out of range on the low side.  This is the case with the Rexa Actuator.  The more robust drive capability of the analog readouts (600 ohms) might also have been a consideration.
• What does the Pre Warm Valve Stroking function do?
  • The manual is incorrect.  The manual indicates you can stroke the governor valve, but the pre-warm function is intended to stroke the TV on a type 1 or type 2 valve configuration.  It does not stroke the governor valve.  On a type 3 valve configuration, there is no throttle valve, so there is nothing to stroke.  The manual indicates that if the speed goes above 100 rpm, the throttle valve will trip.  Again, this is only a throttle valve trip, not a turbine trip.
  • To pre-warm a type 3 configuration with stop valve rather than throttle valves.
    • Reset the governor trip and the turbine trip oil
    • Raise the speed setpoint above the actual speed (turning gear speed).  The PID will try to open the valve, but the LSS is controlled by the valve limiter and the limiter will still be at zero .  There are a number of ways to raise the speed setpoint, including use of the raise command via either a contact input Modbus.
    • Manually take control of the valve limiter.  The valve limiter can be raised via a Modbus valve limiter raise and lower command, or from the keypad by selecting the limiter menu and using the adjust key.
    • Without the speed pid in control, it appears that the limiter will use the medium rate, so recommend setting the valve limiter medium rate to a low value to enhance resolution
• We are not using TPC for this application, but for my understanding;  There is no Modbus Analog Write Register for a Throttle Pressure Control Setpoint.  I perceive that this means we can raise and lower the setpoint via Modbus, but cannot ramp to a setpoint via Modbus.  Can you Confirm?
  • Nevil Brake - 10/28 – Yes from what I see in the gap (56011091.GAP) I can confirm that you cannot ramp to a set point via modbus.
• Confirm that comm link 1 & 2 trip are not on loss of comm, but on comm trip write to register
  • Walter Grassens - Confirmed. The Link Error is a permissive for a shutdown from the Modbus block. A shutdown can only come in on 0:0003 and trip the unit if the comm link is healthy (i.e. there is no link error).
• There is only 1 analog input for both speed and valve position control setpoint.  How does this work?  Can you program only one or the other?  If you can program both, what happens when the breaker closes? Ref Manual Pg 39 & 40
  • Scott Taylor – The same analog input is used both for the speed and VPC setpoints.  They can be scaled differently.  The intent is that on breaker closure the DCS will switch this output from a speed reference to the VPC
  • Tom Truax comment from 11/11:  For simplicity, the control can be configured to use only one of the options
• Speed Sensor Probes.
  • 9/4/08
    • Can we use Active pickups. the short answer from Woodward is Yes
    • The manual shows an active pickup, but indicates it is not used.  Also, there are numerous references to passive pickups in the manual, but none for active pickups.
    • If Active Pickups cannot be used, why not?
    • Spoke with Rich Kamphaus on 9/4.  Rich does not see a reason why you couldn't use the active pickups.
    • Spoke with Scott Taylor.  Scott noted that the hardware is exactly the same, but will look into the code.
  • 9/5/08 Email Reply from Scott
    • I saw exactly what you were describing in the manual, both on page 20 in the wiring examples, where it says not used above proximity probe wiring example, and in the Speed Sensor Input section were all references to proximiter inputs were removed (when compared to the standard 505 manuals).
      The hardware is not different and the software includes the switch that would allow the inputs to read the low speeds that could only come from an active speed probe – so technically there should be no problem using a proximiter.
      I have a voice mail with the engineer that wrote this software and will forward any information he provides.
  • 9/9/08 Email Replay from Scott
    •  ... I did talk to the original engineer on the 505LST – He’s no longer at Woodward otherwise I’d put you in touch with him directly. There should be no problem using an active speed probe. His only concern was that with the max speed selected the resolution might be poor.
• Is the manual 26326 Rev A the most current version?
  • No, Manual 26326 has been superseded by manual 26440
• Is the part number 9907-811, listed on page 1 of the manual, a current part number.  Our procurement staff indicates the current part number may be 9907-169.  We will be using the medium voltage (120 VAC or 125 VDC station battery)
  • The Part Number in manual 26440 is 9907-169.  This is the same part number used at MP
• Does the shutdown output clear after a reset when there is still an active trip input?  How do we deal with looped shutdown logic?
  • There is timer called Reset Trip Delay.  The manual indicates that the External Trip Input is ignored for a time after reset, but the unit will trip if the external trip is not cleared within the configured time.  What the manual does not explain is that there are 2 external trip inputs.  One on terminal 12 (DI:1) and another on terminal 27 (DI:16).  The tune-ability override functionality is only available on DI:16.  The trip input on DI:1 is direct acting and immediate.  There are no provisions to break looped logic on a DI:1 External Trip Shutdown.  If looped logic is an issue, then use DI:16 and jumper DI:1 if DI:1 is not used for some other shutdown input.