NON-DLE_Fuel_V2-1L

8/13/2019 NON-DLE_Fuel_V2-1L

1/28

Fuel Control Main Menu

Fuel Control Objectives

Fuel Function OverviewMechanical System Components

Fuel Function Descriptions

Start Control

N1 ControlN3 Control

N1 Underspeed Control

N2 Control

Pc ControlTe Control

Ambient Bias

Accel Limiter

Decel Limiter

Non-DLE Fuel Control

Rev. 2.1,Feb. 2005Contents Copyright 1990-2005, Rolls-Royce Energy Systems Inc.

1 of 28


2/28


Operate the unit within R-Rdesign specifications

Starting Fuel Flow SchedulingOperate Gas Turbine at a steadystate condition

Provide Loading and UnloadingRates

Provide Operating Limits for:

Gas Generator Acceleration Limiting

Gas Generator Deceleration Limiting

Ambient Temperature Biased PowerLimiting

Safety Monitoring and/or Shutdown

- Gas Generator

- Power Turbine

- Driven Equipment

The fuel controller is responsible forstarting, stopping and normal operation of

the unit. ThePLCcontroller takes data

from unit control devices and uses theinformation to control the following tasksrequired to operate the unit safely.

T1RTD

N1FREQ

N2FREQ

PCDMV

TEKTC

N3FREQ

CTRLPROC

RAMROM

Reg.

ValveDriver

Electric Fuel Valve

ValveFeedback

SequencerCommands

LP - N1

N3H

P H

PLP

LP

HP - N2

PowerTurbine

GasGenerator

AirIntake

AnalogInputs

DigitalInputs

DigitalOutput

AnalogOutput

RegulatorControl

FuelPressure

Status, Alarm andShutdown Outputs

FlexcommCommunications

to Peers and Ft210

2 of 28

Main Menu


3/28


Unit Control Fuel Devices

ThePLCPLCreceives data from unit

transmitters and uses that information todetermine the fuel required to operate theunit.

- N1, N2, N3 and Ns provide

information about the speed of each unit

component.

Speed

Temperature- A number of temperaturedevices are used to calculate the Mass Airflow through the unit while exhaust gastemperatures are used to determine

maximum operating temperature limits.

- Compressor discharge pressure is

used in calculating Mass Air flow, while theregulated fuel pressure and the differentialpressure across the fuel valve is use to

calculate the fuel flow to the engine.

The fuel program evaluates both digital andanalog control signals and determines theproper position of the fuel valve. Feedbackfrom the valve is used by the controller to

verify that the unit is performing as required.

Should the controller detect a problem, it willsend an alarm or shutdown to the UCPcontroller and initiate a safe shutdownsequence for the unit.

PressureT1

RTDN1

FREQN2

FREQPCDMV

TEKTC

N3FREQ

CTRLPROC

RAMROM

Reg.

ValveDriver

Electric Fuel Valve

ValveFeedback

SequencerCommands

LP - N1

N3H

P H

P

LP

LP

HP - N2

PowerTurbine

GasGenerator

AirIntake

AnalogInputs

DigitalInputs

DigitalOutput

AnalogOutput

RegulatorControl

FuelPressure

Status, Alarm andShutdown Outputs

FlexcommCommunications

to Peers and Ft210

3 of 28

Main Menu


4/28

Fuel Control Functions

Fuel Flow

Fuel Flow Measurement providesoperating protection to the GG by:

Fuel Flow is determined by FuelManifold Measurements that include:

ThePLC based fuel controller must providethe proper fuel gas supply to the enginefor the available combustion air deliveredby the gas generators compressor. The

amount of mass air is directly related tocompressor discharge pressure andambient temperature which takes intoconsideration air density.

Knowing the mass air flow the fuelcontroller calculates the required fuelflow needed to operate the gas generator.

Upstream and downstream transmittersprovide the necessary information for

calculating fuel flow through the fuelvalve.

Knowing the mass fuel flow, Constantstable entries provide the controller withthe fuel analysis data to calculate the LHVof the fuel gas. Factoring in LHV results in

a fuel flow measured in BTU/sec.

A constant fuel pressure is maintained bya fuel gas regulator ismonitored by twopressure transmitters and one RTDtemperature sensor.

Acceleration Limiting to eliminate overfueling which causes:

Engine Burner Size

Engine Compressor Discharge pressure

Fuel Analysis

Regulated fuel pressure, fuel valve diff.pressure and gas temperature

Deceleration Limiting prevents flameextinction.

Steady State Operation to preventdamage caused by oscillatory fuel flow.

High Exhaust TemperaturesGG Compressor Stalling

Compressor Surge

Fuel Flow

4 of 28

Main Menu


5/28


Fuel Flow

Fuel FlowLSS HSSPID

PID

A

D

C

C

BTU/SEC

BTU/SEC

BTU/SEC

BTU/SEC

P

C

LB/SECBTU/LB

LHV

Derived from Constantstable entry

Ma

Ma

Zero

Zero

Fuel FlowCalculations

PSIG

PSIG

0-20 Ma

0-20 Ma

ValveUpstream

ValveDownstream

Mass Flow(lb/sec)

Fuel Rate(BTU/sec)

Fuel Heat Value(BTU/lb)

Flow calculations are also used asinputs to both the Acceleration and

Deceleration limiters.

The acceleration limiter comparesthe fuel flow to the output of acurve whose input is compressordischarge pressure.

The deceleration limiter also

compares fuel flow but its setpointis derived from a curve whose inputis N1 speed. As N1 and Pc change,the flow rate setpoint into bothacceleration and decelerationlimiters changes.

5 of 28

Main Menu


6/28


Fuel Flow

LSS

HSSA

D

C

C

BTU/SEC

BTU/SEC

BTU/SEC

BTU/SEC

P

C

PID

PID

10k 10k

0

10 20 30 40 50 100 120 130 140 15060 70 80 90

20k 20k

30k 30k

40k 40k

50k50k

60k60k

70k70k

80k

FUEL

FLOW

N SPEED

lbf/in2

1

Typical Acceleration Line

Worst Weak ExtinctionLine (Gas)

Normal Weak ExtinctionLine (Gas)

Weak Extinction Line (Liquid)

Over fueling limit

Applicable at ISOConditions

AVON Example

GG Compressor Deliver Static Pressure

The fuel controller uses fuel flow to determinethe setpoints to both the acceleration limiter andthe deceleration limiter.

Compressor discharge pressure is the input to a

curve whos output is fuel flow and becomes thesetpoint into the acceleration limiter.

The deceleration limiter prevents the gasgenerator from flaming out. The setpointinput to the deceleration limit is a curvewhose input is N1 speed.

To the right is a chart example of anAVON unit and its acceleration anddeceleration lines. Note the differencebetween the weak extinction linesbetween liquid fuel and gas.

Both acceleration and decelerationcurves may be viewed dynamically from

theHMI (FT310)but may not be modified.

6 of 28

Main Menu


7/28


Fuel Flow

Fuel Gas Regulator

and Flow Meter

Fuel Gas Regulator

Fuel Valve and Flow Meter

Fuel

Valve

7 of 28

Main Menu


8/28


Fuel Valve Control - Valve Driver

Ma

HSS

PID

%

Position Setpointfrom Flow Loop

ZeroGain

Q

LVDT FeedbackLoop

V Ma ACT

DRVR

4-20 Ma

4-20 Ma

-60 - +60Ma

Fuel DemandSetpoint Signal

Actual Valve OpenPosition Feedback

Percentage

Actuator Driver/LVDT Conditioner

Engine FuelManifold

Fuel GasSupply

FuelValve

12.5%

0%

0%

87.5%

100%

100%

1 INCH STROKE

3/4 INCH STROKE

ACTUATOR STROKE

VALVE STROKE

Valve ZeroPosition

An LVDT or RVDT, an integral part of thefuel valve, sends back information onthe actual position of the fuel valve. Thecontroller uses valve position data as aninput to the valve driver PID. Theoutput from the driver increases ordecreases until the actual valve positionmatches the setpoint the controller istrying to achieve.

The above graphic shows that the output of the fuel

controller is a 4 - 20 mA signal to the fuel valvedriver card which amplifies this signal to a highercurrent. Depending on the type of fuel valve used,the higher current drives a hydraulic servo valve tomove the fuel valve. If electric fuel valves are used,the output to the fuel valve is generated by the fuel

controllers electric valve driver card.

8 of 28

Main Menu


9/28


Valve Position Feedback

12.5%

0%

0%

CLOSE OPEN

87.5%

100%

100%

1 INCH STROKE

3/4 INCH STROKE

ACTUATOR STROKE

VALVE STROKE

Linear Variable Differential TransformerFeedback Signal

Physical Valve Movement

GAIN

1.333

=

=

ACTUATOR STROKE

1.00

VALVE STROKE

0.75

VALVE POSITION =

GAIN(VALVE ZERO POSITION)

-ACTUATOR STROKE

The initial position of the fuel valve must be

entered into the PLCs Constants whenthe valve is initially installed or change. Entriesmay include, the feedback when the valve is

fully closed and the gain of the feedback signalwhich takes into consideration that the stoke ofthe LVDT is greater than the stoke of the valve.

The following formulas can be used todetermine the actual valve position when thefeedback signal is known.

The stroke of the LVDT is factory matched to thestroke of fuel valve. When the fuel valve is 50%

open, the LVDT is at the center of its stoke.

9 of 28

Main Menu


10/28

Basic Fuel System Components

S

FUELVALVE

FUELISOLATION

VALVE

Accumulator

Servo

Valve

Actuator

FUEL GASREGULATOR

Actuator Drain

Regulator Pressure mustbe measured a minimum

distance of 5 X (InsidePipe Diameter) Max. Back Presssure

= 25 PSIG

Critical Minimum Distance

Min5 d

Filter

Actuator HydraulicOil Supply

All fuel systems are made up of three basic components. A regulator to control the supplypressure, a fuel shutoff solenoid valve to isolate fuel from the engine when the unit is down,and a fuel valve. In the above case the fuel valve is a hydraulically operated valve requiring ahydraulic oil supply. When an electric fuel valve is used, no hydraulic oil is required.

Note above that distances between components is critical and requires the fuel components

be mounted close to the engine.

Fuel Control Components

10 of 28

Main Menu


11/28

Fuel Flow Transmitter

Although the fuel valve is extremely accurate,the fuel controller does not totally rely on the

accuracy of the pressure transmitters. A optionalflow transmitter installed prior to the fuel valve

measures the fuel flow in the manifold. ThePLCsoftware compares the flow transmitterdata to the calculated fuel flow.

The upper photo shows the electric fuelvalve with upstream and downstream

transmitter connections. Behind the valveand in the photo to the right is the fuel flowtransmitter. The large pipe is the fuelregulator loop that supplies multiple fuelmanifolds for an RB211 DLE. Note theregulated fuel pressure transmitter

connections.

Fuel Control Components

11 of 28

Main Menu


12/28

Fuel Gas Regulator

Fuel Control ComponentsThe photo at the left shows the fuel gasregulator supply loop. A high speed shut-offvalve shown in the upper left of the photoisolates fuel gas when the unit is down. The

regulator assures a constant fuel gas supplypressure through the entire fuel flow range.

The regulator is normally operated in two stages. Alower pressure during starting allows for moreaccurate positioning of the fuel valve for the smallflow rate required to start the unit.

Once the gas generator reaches idle, the regulatorpressure is increased. To compensate for anincrease in supply pressure. the fuel valve closesdown to maintain the desiredfuel flow.

12 of 28

Main Menu


13/28

Fuel Gas Regulator Supply Loop

Fuel Control ComponentsThe complete fuel gasregulator supply loop is showat the left. Some additionalcomponents are indicated inthe diagram. The two supplypressure transmitter and theaddition of two solenoidsmounted to the support. Thelarge solenoid is responsiblefor changing the regulatorpressure when the unit

reaches idle. The accumulatordampens the change inpressure.

The small solenoid at the topof the support stand works in

conjunction with the highspeed shut-off valve. Whenthe unit is down and gas hasbeen isolated from theregulator, the solenoid ventsfuel gas from the fuelmanifold to atmosphere.

13 of 28

Main Menu


14/28

Fuel Control System Diagram

OHM

Ma

Ma

Ma

SPD

SPD

PID

SS

SS

SS

SSPID

PID

PID

PID

RPM

F

%

PSIG

PSIGSPD

Parameter Control Loop Signal

Position Setpointfrom Flow Loop

To Actuator

ABFILT

Zero

ZERO

ZERO

ABFILT

T1PWRLMT

Gain

HYS

T1

PWRLMT

Hz

PIDRPM

ABFILT

T1PWRLMT

Hz

SPD

PIDRPM

ABFILTHz

PIDPSIG ZERO

T1PWRLMT

Ma

SPD

PIDF LEAD

COMPAB

FILT

BTU/SEC

BTU/SEC

BTU/SEC

BTU/SEC

BTU/SEC

T1PWRLMT

MV

T

T

T

T

T

N

N U

N

N

N

PP

F

T

A

D

Q

V T

1

1

1

1

1

1

1

1

2

3

C

C

F

E

C

C

V

PARAMETERCONTROLLER

ENGINESCHEDULED

LIMITERS

PRIMARYCONTROLLER

INT

RPM HYS

CNTLMa

Local Control

Fuel Software Components

Fuel FlowCalc. &

FlowCompens.

The total fuel control system isrepresented by this blockdiagram.

For a more detailed descriptionof any controller, click on theappropriate portion of thediagram.

14 of 28

Main Menu

Fuel Flow


15/28

100%

Time

FN

N

N T P

T Bias Signal

F

F F

1

N 1

3

N3

2

N 2

E

T E

C

PC

1

T 1

Fuel Flow

IP Shaft Speed

HP Shaft Speed

Power Turbine Speed

Compressor Discharge Pressure

Exhaust Temperature

Inlet Temperature

a a a a

N1 UpperLimit

N1 LowerLimit

Fuel ManifoldPressure

Upper Limit

N3 UpperLimit

N3 Lower

Limit

Gas Turbine ParameterControl Loop

N2 UpperLimit

Exh. Gas Temp.Upper Limit

CDP PressureUpper Limit

0%

Speed (%)

a a a a

StartControlN1Con

tro

l

Nom

inal

N3Con

tro

l

Idle

Min Load.

Unit Limits

Fuel On

The red line in the graph above shows a idealized start ovelayed on the control modes. From Fuel On to N1 Idle, the display will showStart Control. From N1 Idle to Minimum Load, The Diplay will show N1 Control. And from Minimum load through 100% load, you will

typically see the display in N3 Control unless one of the system parameters for N1, N2, Te, or Pc come into play, switching Fuel control

into one of those modes.

15 of 28


16/28


Start Control

Start Control

Ma

Ma

Zero

Zero


& FlowCompensation

PSIG

Flow MeterLHV of

Fuel Gas

PSIG

SPD

0-20 Ma

0-20 Ma

Fuel ManifoldPressure Signals

ValveUpstream

ValveDownstream

Fuel ValvePosition Setpoint

%INT

The Start Control Setpoint driverschedules fuel to the GG from theFuel On command until N1 Idlehas been achieved. Fuel flow is

compared to the flow scheduled bythe setpoint driver. A pair oftransmitters measure the upstreamand downstream pressure acrossthe fuel valve. Along with theregulated pressure and temperature

the controller is able to calculatethe fuel flow in pounds/second.

Calculating in the LHV of the fuel,the output of the flow calculationsbecomes BTU/sec.

An in line flow meter is used toverifies the accuracy of the flowrate calculations. Should thecontroller detect an error betweenthe two, appropriate action will betaken.

SETPOINT DRIVER FUNCTIONS

Increase fuel flow rate at a slow rate froma low ignition point to a high ignition point

Increase fuel flow at a calculated rate tosafely achieve N1 idle speed.

Limit the maximum fuel flow and manifoldpressure.

Instantaneous fuel flow increase to a flowrate less than required for ignition.

16 of 28

Main Menu


17/28


10

10

20

20

30

30

40

40

50

50 60 70 80

Fuel

Man

ifo

ldPressure

S

etpo

int

,P

SIG

Time (sec)

Low Ignition Point (Preset 1)

High Ignition Point (Preset 2)

SlowRate

Ignition

Verification

GG IdlePoint

Preset 3

Start Control Setpoint Driver

During the initial start the fuel valve is scheduledby the action of the setpoint driver. An inital stepbrings the fuel valve open to the Low Ignitionpoint which is defined as a fuel flow that will notresult in ignition. The fuel valve is then integratedtoward the High Ignition point at a slow rate.Between the Low and High Ignition point the

fuel and air mixture will ignite. Ignitionis verified by the measurement of therate of change of the exhaust gastemperature. When the controller sees a6 degree F/sec rise in temperature,ignition has been verified. The setpoint

driver now continues to open the fuelvalve at a medium rate until the gasgenerator reaches idle speed. The N1controller takes control at idle and theStart Controller moves to the top at afast rate to become the high fuel

pressure limiters.

Start Control

Ma

Ma

Zero

Zero


& FlowCompensation

PSIG

Flow Meter

LHV ofFuel Gas

PSIG

SPD

0-20 Ma

0-20 Ma

Fuel ManifoldPressure Signals

ValveUpstream

ValveDownstream

Fuel ValvePosition Setpoint

%INT

17 of 28

Main Menu


18/28


N1 Control

N Control1

SPD

PID

LSS

RPM AB

FILT

T1

PWR

LMT

TPWRMT

Hz

T

N

1

1

The N1 Speed Controller assures the GG safelymaintains Idle speed during warmup. When theload command is issued the GG will accelerate tounit load speed where N3 takes control.

N1 speed control continues to drive to its upperlimit and becomes N1s upper speed limit.

Since N1 is also ambient biased, the upper limitwill lower when ambient temperatures drop tolow.

Reduces the upper limit speed setpoint atlower ambient temperatures because N1 is

sensitive to Air Density.

When the air is less dense (warmer), thespeed of N1 must be higher to achieve thesame power that can be achieved withdenser (colder) air at lower ambient

temperatures.

T BIAS1

The setpoint driver consists of a lower limit, Idle,a load limit and an upper limit, and the

appropriate drive rates from one limit to thenext.

SETPOINT DRIVER

The Unit Power Rating

GG Inlet Temperature (T1), or ambient bias

18 of 28

Main Menu


19/28


N1 Control

20

0

40

60

80

100

N

1S

pee

d(%

)

Time

GG Idle Point

N3 Control Point

GG Base Power Rating

GG Peak Power Rating

GG Max Power Rating

WarmupPeriod

27 Pulses/RevN SpeedSignal1

SPD

PID

LSS

RPM AB

FILTHzN1

T

PowerRatingN1LIMIT

LSS

1

Once N3 assumes control, The N1 setpointcontinues to drive to its upper limit and becomethe N1 upper limit controller.

The above diagram shows N1s upper limit isambient biased to reduce N1 maximum speedwhen ambient temperatures drop.

The three power ratings indicate an elevation ofthe gas generator upper limit allowing customersto operate the unit with higher than normalpower output but reduces the time between gasgenerator overhauls.

N1 speed pulses are converted to RPM andfiltered before they become the input to theN1 PID controller.

The setpoint driver below shows N1s

control range starts at idle and continuesuntil N3 speed reaches its control rangelower limit.

19 of 28

Main Menu


20/28


Fuel Valve Control - N3 Control

N Control3

SPD

PID

LSS

RPM

RPM

ABFILT

HYSCNTL

Hz

Ma

N3

The N3 Controller is used to controlPower Turbine speed. The drivenequipment and process parametersentered in the Constants table determine

the minimum and maximum speed range.

The Hysteresis controller is used todampen the remote speed setpoint signal,avoiding the effects of noise generatedinstability on the remote current loop.

HYSTERESIS CONTROL

The setpoint driver determines the lower tothe upper limit speed limits. The signalmoving the speed upward or downwardoriginates from;

Local or remote manual Increase/Decrease Contacts

Local or remote speed control fromprocess controllers.

The upper Limit is determined by the

unit power rating.

SETPOINT DRIVER

Remote Control

Local Control

20 of 28

Main Menu


21/28


N3 Control

20

0

40

60

80

100

N3

Spee

d(%

)

Time

N3 Idle Point andWarmup Period

N3 Lower Limit andControl Point

GG Base Power Rating andN3 Upper Limit

GG Peak Power RatingGG Max Power Rating

N3 acceleration

under N1 control

N Control3

SPD

PID

LSS

RPM

RPM

ABFILT

HYSCNTL

Hz

Ma

N3Remote Control

Local Control

N3 speed pulses are converted to RPM andfiltered to remove noise. N3 speed is thencompared to one of two setpoint inputs. TheLocal Control loop is controlled by theincrease or decrease button on the front of

the control panel. The remote signal is thecustomer speed control input.

The upper and lower limits of the setpoint

driver are entries in thePLC constants.In most cases the upper limit of a controllercan not be moved. N3 though must bemoved in order to test power turbine

overspeed. Increase N3s upper limit bychanging the value in theconstants

and download the new value to the PLC.N3 speed can now be increased aboveoverspeed setpoint by pressing the speedincrease button. (Use with extreme

caution.)

21 of 28

Main Menu


22/28


N1 Underspeed Control

Setpoint selector values determine theminimum operating power during normaloperation. During starting, the N1Underspeed function is bypassed. At allother times the second value determinesminimum power output at idle. Additionalsetpoints can be added to determine aminimum load speed.

The controller forces the Gas Generator to maintaina minimum power output during idle and loadedoperation by preventing the fuel valve from closingfurther even though the fuel demand from theParameter Control Loop calls for a further reductionin speed.

Setpoints entered in the constants table determinethe minimum power setting for various operatingconditions. In most instances this controller is usedto set a minimum N1 speed just below idle speed,

but in some cases the controller has also been

used as a two stage controller by addinganother setpoint used as a minimum power

setpoint.

Although adding a setpoint is an option, thesetpoint just below idle should not be removed.Should the GG drop below the N1 Underspeedsetpoint the unit may be operating in a highvibration area resulting in damage to the gas

generator.

N Underspeed Control1

SPD

HSSLSS

PID


N

U11

22 of 28

Main Menu


23/28


N2 Control

N Control2

PID

LSSRPM

AB

FILT

T1PWRLMT

Hz

T

N

1

2

The GG N2 Speed Controller is a maximumlimiting control to prevent operation above a setN2 speed.

The starter motor turns the N2 rotor toestablish combustion air for ignition and assistsN2 until the GG obtains self sustaining speed.

In normal operation N2 rotor operatesindependently at a higher speed than the N1rotor.

T BIAS1

Two factors determine the setpoint value forthe upper operating limit:

SETPOINT


GG Inlet Temperature (T1) ambient bias

Reduces the upper limit setpoint at lowerambient temperatures because thisparameter is sensitive to Air Density.

When the air is less dense (warmer), thisparameter may need to be higher to achievethe same power that can be achieved withdenser (colder) air at a lower ambienttemperature.

23 of 28

Main Menu


24/28


P ControlC

The fuel controller monitors the gasgenerators compressor discharge pressure.The maximum allowable pressure is an entry inthe Constants table. When the actualcompressor discharge pressure matches the

setpoint, the fuel valve not be allowed to openfurther.

Compressor discharge pressure is also an inputinto the schedule where themaximum fuel flow rate allowed duringacceleration is dependent on compressordischarge pressure.

acceleration

Reduces the upper limit setpoint at lower

ambient temperatures because thisparameter is sensitive to Air Density.

When the air is less dense (warmer), thisparameter may need to be higher to achievethe same power that can be achieved withdenser (colder) air at a lower ambient

temperature.

T BIAS1

Two factors determine the setpoint for the

upper operating limit:

SETPOINT



P ControlC

PIDPSIG ZERO

T1PWRLMT

Ma

P

C

LSS

24 of 28

Main Menu


25/28


T ControlE

The GG Exhaust Temperature Controller is amaximum temperature limiting controller toprevent over temperature operation.

When the temperature reaches the limitingvalue, the fuel controller will not allow a fuelincrease even though N3 has not reached itsupper limit.

The measured values are derived from a set ofthermocouples located in the exhaust cone of

the GG.

Reduces the upper limit speed setpoint atlower ambient temperatures because N1 issensitive to Air Density.

When the air is less dense (warmer), thespeed of N1 must be higher to achieve thesame power that can be achieved withdenser (colder) air at a lower ambienttemperature.

T BIAS1

The upper limit is determined by three factors:

SETPOINT



Decreased Max. Temp. Setpoint for Start(RB211 Only)

T ControlE

LSSSPD

PIDF LEAD

COMP

AB

FILT

T1PWRLMT

MV

T

T

1

E

25 of 28

Main Menu


26/28

Ambient Bias

The chart at the left shows the Exhaust GasPower rating for an engine and the effect ofambient temperature on the output power. Athigh temperatures, when the air is less dense, the

power output is considerably reduced. At verylow temperatures the air density increases to thepoint where the available air exceeds the powerrating of the gas generator.

To prevent exceeding the power limits of theengine, as the ambient temperature drops, sodoes the maximum N1 speed at which the enginecan operate.

ThePLC measured ambient temperature inputis read in ohms and converted to degrees F. Theinformation is then filtered to remove noise and

becomes the input to the power limiting curvecontained in the controller.

Ex

haus

tG

as

Power

N1Spee

d

Rev

/Min

12K

12K

-30 -20 -10

-10

0

0

10

10

20

20

30

30 40 50 60 80 10070 90 110

40 50

16K

18K

20K

22K

24K

26K

28K

30K

7000

7500

8000

O

O

F

C

Base

Base

Peak

Peak

Emergency

Emergency

Ambient Temperature

120

OHM F AB

FILT

T1PWRLMT

T


26 of 28

Main Menu


27/28


Acceleration Limiter

Acceleration Limiter

P


P AC C

FuelFlow

Rolls - Royce supplies the

schedule that determines the

fuel flow rate for a certain

Compressor Discharge pressure.

The curve output becomes the

PID setpoint.

To prevent an over fueling condition which could

result in compressor surge, the Acceleration

Limiter output is compared to the Parameter

Control Loop Output.

Low signal selection determines which signal

becomes the fuel demand signal.

LB/SEC

BTU/LB

BTU/SEC

BTU/SEC

LHV Fuel FlowCalculations

PCBTU/SEC

The actual measured value which

the controller compares to the

manufacturer's schedule is

calculated by the BTU content of

the fuel gas and the mass fuel

flow.

LB/SEC

BTU/LB

BTU/SEC

LHV


FuelFlow

27 of 28

Main Menu


28/28


Deceleration Limiter

Rolls - Royce supplies theschedule that determines the fuelflow rate for a certain N1 speed.The curve output becomes the PIDsetpoint.

The actual measured value whichthe controller compares to themanufacturer's schedule iscalculated by the BTU content ofthe fuel gas and the mass fuel flow.

To prevent an under fueling condition which

could result in a flame-out condition, the

Deceleration Limiter output is compared to the

Parameter Control Loop Output. The High Signal

Selector determines the maximum signal, which

then becomes the fuel demand signal.

Deceleration Limiter

HSS

N

N

1

1

Fuel Demand FromAcceleration Limiter

BTU/SEC

FuelFlow LB/SEC

BTU/LB

BTU/SEC

LHV


P DC

LB/SEC

BTU/LB

BTU/SEC

LHV

Fuel Flow

Calculations

Fuel

Flow

28 of 28

Main Menu

Documents

NON-DLE_Fuel_V2-1L