NOAA Rainier Control Philosophy.pdf

1553-CP-001

Revision Number A

NOAA RAINIER

CPP SYSTEM UPGRADE

CONTRACT NO. AB133M17BA0030

CONTROL PHILOSOPHY

Verus Project No. 1553

July 2021 15-July-21

Revision Status

Revision Date Description Author Checked By Approved By

A 07/15/2021 Issued for Review A. Wilson D. Sandstrom J. Kranz

Rev: A Date: 15-July-21

1553-CP-001

Table of Contents

1 SUMMARY AND CLARIFICATIONS 4

2 CONTROL STRATEGY OVERVIEW 5

3 EMERGENCY PITCH CONTROL 5

4 STATION IN CONTROL 6

5 LEVERS LINED UP 7

6 SPLIT MODE 8

7 COMBINED MODE OPERATION 9

8 ENGINE SYNC FUNCTION 10

9 STARTING/STOPPING ENGINES 11

10 SYSTEM MONITORING 11

1 SUMMARY AND CLARIFICATIONS

Date: June 25, 2021

Project: Rainier CPP Control System Upgrade

Verus Project No. 1553

Reference: CPP System Upgrade Control System Drawings

Subject: Controllable Pitch Propellor Control Philosophy

Purpose: This document describes the operation of the control systems for the controllable pitch propeller (CPP) aboard the NOAA vessel Rainier. Aboard the Rainier the CPP control systems control both propeller pitch and engine speed for the related engine.

2 CONTROL STRATEGY OVERVIEW

The controllable pitch propeller allows the ship’s crew to adjust the propeller’s pitch to match sea state or other ship requirements. By controlling propeller pitch the related engine can be operated in an ideal load band regardless of ship speed or direction.

The CPP control system controls the port and starboard engine/propeller systems separately. For each drivetrain there are two standard control modes: split, and combined. In addition to the standard control modes the engine room console has the ability to engage an “emergency” control mode.

SPLIT MODE CONTROLS

In split mode control the engine speed and propeller pitch for each drivetrain are controlled separately/independently. The controlling station sets a pitch value for the propeller and a speed value for the engine and the controller maintains these values. There is no integration between the two, however, the CPP control system will monitor total engine load and reduce engine speed (despite command settings otherwise) to prevent an engine overload.

COMBINED MODE CONTROLS

In combined mode each drivetrain is treated as a single unit. The CPP control system adjusts propeller pitch and engine speed together to maintain the engine within optimum load parameters while adjusting pitch for best speed at that RPM. This is accomplished through a set of programmed tables of engine speed, load, horsepower, and propeller pitch.

EMERGENCY MODE CONTROLS

The emergency mode control bypasses the CPP controller and sends pushbutton controls from the engine room console directly to the propeller pitch control and the engine governor. This allows the engine room staff to bypass a faulted or errant controller if required.

3 EMERGENCY PITCH CONTROL

Emergency pitch control is initiated from a three-position switch in the engine room console (S13). The normal operating position is “Auto”, allowing the CPP system described in this manual to control the propellers.

The remaining two positions, “ER” and “PH” electrically disconnect the pitch control solenoids from the CPP control system and connect them to four momentary pushbuttons on either the Engine Room (“ER” position) console or the Pilothouse (“PH” position) console. Selection of Emergency Mode, and selection of the control station as the ER or PH is only available at the mode selection switch in the ER console. As a corollary, return to normal operation can only be achieved by switching back to “Auto” at the ER console.

In Emergency Mode none of the other control transfer functions described in this manual are available – they will not work.

The four momentary pushbuttons S8-S11 provide forward and astern pitch control for each propeller.

When a pushbutton is pressed a direct 24V connection is made between the control panel and the related pitch control solenoid in the engine room. The solenoid will remain open, driving the propeller pitch in the desired direction until the switch is released by the operator. A separate bar graph pitch indicator on the ER and PH consoles is connected to redundant pitch transducers at the pitch control solenoid box.

This bar graph is intended to provide pitch feedback information to the operator in Emergency Mode in case the CPP system feedback at the pitch header is not operational. In normal operation the bar graph and the pitch header feedback should both operate, and the displayed values should be identical (within sensor tolerances). If no feedback values are displayed in Emergency Mode the operator should request direct manual readings from ER staff.

The CPP control system is inactive in Emergency mode, it is up to the operator and the engine room team to prevent engine overload. Engine speed control in Emergency Mode is accomplished by engine room staff manually adjusting the fuel governor for each engine.

In Emergency mode there is no pitch maintaining function active; the pushbuttons are the only source of pitch change commands. Propeller pitch may drift over time and must be observed and corrected manually (the CPP system contains logic to automatically monitor and correct for pitch drift when in Auto mode).

Returning from Emergency service is accomplished by returning S13 in the ER console to the “Auto” position. The Station In Control indication will show the location of the control station that will be used by the CPP system. If a bumpless transfer is desired the Levers Lined Up functions should be used prior to switching the system back to the Auto position.

4 STATION IN CONTROL

The Station In Control logic tracks which console/station is controlling the vessel. There are two “master” stations, the Engine Room and the Pilothouse. Control is transferred between these two as described by this section. In addition, the Pilothouse has two slave stations, the Port Wing and Starboard Wing station.

When the Pilothouse is in control it may delegate its control to either of the wing stations.

Each station has two engine speed pots as well as two propeller pitch headers (as well as additional discrete controls depending on the station). When a station is in control the CPP system uses the readings from the controls at that station to control engine speed and propeller pitch; the signals from the remaining stations are ignored.

The default condition is Engine Room in control. In the ER in control mode the CPP system uses the pitch position and engine speed pots on the Engine Room console as the control source for propeller pitch and engine speed commands.

Prior to using any of the control transfer functions the LLU procedures should be completed to provide bumpless transfer between the control stations.

TRANSFERRING CONTROL TO ENGINE ROOM

The Engine Room can take over control at any time by using the “Take Over In Control” pushbutton on the ER console. The Take Over In Control pushbutton will be illuminated and the CPP system will immediately transfer control to the ER station. The ER station is the only station with the ability to commandeer command, in effect it has an override priority over all the other stations. When the ER is in control the CPP system illuminates the “ER In Control” pilot lights on the PH, PW, and SW consoles and extinguishes the lights for control and control requests on the bridge.

TRANSFERRING CONTROL ER TO PH

When the Pilothouse wants control of the system the operator in the PH presses the “Request Control” pushbutton, which will then become illuminated. This signal is then passed to the ER where the “Request Control PH” pilot light blinks on the ER console. If the engineering officer on watch accepts the request the engine room operator presses “Control to Pilothouse” button causing the PH “Take Over In Control” pushbutton to blink. When the PH watch is ready to assume control they then press the PH “Take Over In Control” button. The PH “Station In Control” light will become steadily illuminated to indicate control has passed. It is at this point that control is actually transferred and the CPP system begins using the signals from the PH consoles to control the system. The “PH In Control” indicators in the engine room and on each wing station will also be illuminated. The request and takeover buttons are extinguished at both stations.

The entire transfer sequence must be completed within 30 seconds. If the transfer request is not completed the CPP system cancels the request and returns all lights to the ER in control status.

DELEGATING CONTROL PH TO WING STATION

When the main PH console is in control a wing station operator may immediately take control by pressing the “Request Control” button on the wing. The transfer is immediate, no response is required at the PH console. This immediate transfer only occurs if the main PH console is in control (i.e. the port wing cannot obtain control this way if the starboard wing is in control and neither wing can gain control if the ER is in control). The PW or SW In Control light will be illuminated on the PH console, the “Station in Control” light will be illuminated on the wing console in control, and the “PH In Control” light will remain illuminated on the other wing.

To transfer control from PW to SW or vice versa the PH “Take Over In Control” must be pressed to return control to the main PH console, then the other wing may use the “Request Control” button to obtain control.

5 LEVERS LINED UP

The engine speed and propeller pitch controls are not motorized, thus the control stations cannot know the position of the levers/controls at the other stations. Because of this it is possible for one station to have controls at full astern while another has the controls at full ahead. When transferring control between stations the Levers Lined Up routine can be used to provide bumpless transfer between stations.

The LLU routine works differently in Split Mode and Combined Mode. In Combined Mode the pitch header is used for both engine speed and pitch control and the speed pots are not used. In this case LLU is indicated when the pitch headers match the controlling station’s pitch headers. In Split Mode both the engine speed pot and the pitch header must match for LLU to be indicated.

The initial CPP design aboard the Rainier used LLU lights at each station to indicate that the lever positions matched those of the controlling station. A series of blinking light codes and solid illumination of the LLU light allowed the operator to match conditions at the station in control. This system remains in place with the new CPP system but is augmented by displays within the MACS system and the CPP OIT at the PH console.

LLU LIGHT CODES

When there is a mismatch between the Split/Combined switch position at the inactive station and the station in control the LLU light at the inactive station will blink every three seconds. This must be corrected by changing the Split/Combined mode switch to match the active control station.

Split Mode LLU Light Codes

In Split Mode the speed pots must be aligned. The LLU will initially be dark, the operator slowly adjusts the speed pot until the LLU light begins flashing once per second to indicate that the speed pots are in the same position as the station in control.

LINING UP LEVERS

Finally, when the speed pots are aligned and LLU lights are flashing once per second (Split Mode) or extinguished (Combined Mode) the pitch levers are slowly operated until the LLU light becomes solidly illuminated, indicating that all controls are in the same position as the currently active control station.

Voice communication between the active control station and the station lining up levers simplifies the process by allowing the idle station operator to position the controls at approximately the same position as the active control station before fine tuning through the LLU light sequences.

LLU CONTROL USING MACS/OIT

The CPP system continuously monitors the position of all pitch header and speed pots in the system. The values from all eight speed pots and eight pitch headers are displayed on the MACS system screens in the ER and PH, and on the dedicated CPP OIT on the PH control console. To line up levers on the non-active stations, these screens should be used. The values from the active control stations are highlighted on the screen. The levers and/or speed pots at the inactive station(s) should be adjusted until the values shown for that station on the screen closely match the values for the station in control.

When the controls match (within a small tolerance) the CPP system will indicate this on the MACS screens, on the CPP OIT, and by illuminating the LLU light at the station(s) where the levers (and speed pots in Split Mode) match the values at the station in control. For the wing stations, since there is no display available, this should be accomplished by either using the LLU light alone or by communicating with an observer at the OIT in the PH who can relay the required adjustments to the operator of the wing station.

6 SPLIT MODE

Split Mode control is characterized by separate controls for engine speed and propeller pitch. This is somewhat a manual control, so proper procedures as described in this section should be followed to reduce the chance of engine overload while operating in Split Mode.

SWITCHING TO SPLIT MODE

The station in control may switch either drivetrain to Split Mode by switching the Split/Combined control switch to the “Split” position. If operating in Combined mode with pitch on the transfer should be made by either a) reducing pitch to zero, or b) using the LLU routines to adjust the speed pot(s) so that they match the engine speed under combined mode prior to transferring to Split Mode. Since the engine will immediately begin responding to the speed pot, failure to match conditions (LLU) or adjust pitch to zero could result in engine overload with possible engine damage as a result. To reduce (but not eliminate) risks involved with this transfer the CPP system is programmed with a one RPM per second (shaft speed) engine speed ramp when switching from Combined Mode to Split Mode.

SPLIT MODE OPERATION

When starting operation in Split Mode engine speed should be adjusted first, with reduced load by having no or low pitch set on the pitch header. Once the engine has reached the desired speed load should be applied slowly by adjusting the pitch header as desired to apply load to the engine. When reducing engine speed the opposite procedure should be followed, reduce load by reducing pitch then reduce engine speed.

In Split Mode the engine speed pot is the primary controlling device – the CPP will attempt to maintain engine speed from idle to full speed based on the position of the speed pot. A zero signal on the speed pot represents a request for idle speed (~110 shaft RPM) while 100% on the speed pot represents a request for full speed (~255 shaft RPM).

The pitch header is a secondary control, the CPP will attempt to adjust pitch to the desired setting within the load limits for the engine at the specified speed setting. Pitch header controls and pitch header feedback in are in percent of maximum pitch. Maximum pitch is 10.5 feet, in the ahead position the pitch header control represents a request for pitch from zero (0% on header) to 10.5 feet (100% on header control. In the astern position the same is true, however, the CPP limits astern pitch to 6.5 feet (approximately 62%). If the pitch header is placed in an astern position greater than 62% the CPP system will limit the pitch output to 6.5 feet.

The CPP system monitors engine load by monitoring the fuel rack position and is programmed with a table of maximum fuel rack position values for various engine speeds. Exceeding these values indicates an engine overload condition. If the pitch header is advanced further than the engine can handle without overload then the CPP system will limit the applied pitch to the maximum that can be used without resulting in engine overload. For example, if the engine speed is set at 50% the maximum allowable pitch in forward (the load limits differ between forward and reverse) is *TBD*. If the pitch header at the control station is pushed beyond this point the CPP will limit actual applied pitch to match the engine load limit.

Note that the engine load/propeller pitch limits are not fixed, variable displacement operations such as towing, pushing, or similar operations may result in load outside the normal curve for the same pitch. The CPP system monitors the engine load and attempts to adjust pitch to match the setting as commanded. If boat operating conditions differ from the pre-programmed load/pitch profile the CPP system will attempt to compensate for these conditions and may limit available pitch to values outside the normal operating

7 COMBINED MODE OPERATION

Combined mode operation is selected by switching the Split/Combined switch at the active control station to the “Combined” position. As with the change from Combined to Split mode, the operator should set the controls to match current situation using the LLU routines prior to making the switch or set the pitch to zero on the pitch header to unload the engine.

In Combined Mode the pitch header is the only control point and essentially acts as a throttle. Zero on the pitch header represents engine at idle and zero pitch. 100% represents full speed at the engine governor.

The CPP adjusts the engine speed to match pitch header/throttle position, and then continuously adjusts the propeller pitch to reach the maximum load point of the engine at that speed. In steady conditions the CPP may adjust the pitch once to the target setting and then make only adjustments for pitch drift. In a variable load condition (sea state, starting or recovering tows, etc.) the CPP may adjust propeller pitch more regularly to maintain steady loading on the engine.

8 ENGINE SYNC FUNCTION

In either Split or Combined mode, when the active control station is commanding engine speed within XX shaft RPM of the other engine the CPP system will assume that synchronized operation is desired. In this case the CPP system will internally make the PME the “master” engine and will use feedback from the shaft speed sensors to adjust the SME speed to match that of the PME. In Combined Mode both engine speed and pitch will be synchronized. This function will be automatically deactivated when the speed pots (Split Mode) or the pitch headers (Combined Mode) are not within auto sync range of each other.

9 STARTING/STOPPING ENGINES

Starting and stopping the main engines is controlled directly by pushbuttons and switches on the ER and PH consoles outside the CPP system.

STOPPING ENGINE(S)

The ER and PH console both have a PME Stop and an SME Stop pushbutton. These buttons are always active, pushing the stop button will cause the control relays in the engine room to command the affected engine(s) to stop.

STARTING ENGINE(S)

Primary control of the engine starting procedure lies with the ER console. A start button for each engine on the ER console allows ER staff to start the engine. The buttons are interlocked with Turning Gear signals for the respective engine. If the Turning Gear is not ready the button will not be active. This interlock is indicated by a “Ready to Start” light on the ER console.

The PH console contains the same engine start buttons and ready to start lamps as the ER console. By default these buttons and lights are inactive. A “PH Permission to Start” switch on the ER console connects the PH buttons to the engine starting controls. When the “PH Permission to Start” switch is in the “PH” position both the ER and PH buttons are active and the engine may be started from either location (so long as the interlocks are satisfied).

10 SYSTEM MONITORING

The CPP system monitors several conditions and provides annunciation of these conditions through lights on the console(s).

WRONG DIRECTION

When the station in control requests a pitch change from ahead to astern or vice versa the CPP system initiates the command by sending signals to the pitch control solenoids. If the measured pitch return signal does not indicate that the pitch has switched directions within the configured time delay (default 30 seconds) the “Wrong Direction” light is illuminated on all consoles. The light is extinguished when either

a) the pitch reaches the commanded point or b) when the pitch command at the controlling station is changed to match the actual pitch.

ENGINE OVERLOAD

When operating in either Split or Combined mode the CPP systems monitors engine load by monitoring feedback from the fuel rack position. The CPP system is programmed with a curve for the maximum fuel rack position at various engine speeds. If this value is exceeded the CPP system generates the overload alarm for the engine(s) in question and illuminates the overload light. When operating at maximum load the overload alarm has a variable timer delay to eliminate nuisance alarms; overloads between 100 and 105% have 10-second delay, overload greater than 105% have a 2-second delay.

11 PLC REDUNDANCY SYNCHRONIZATION AND MONITORING

TBD