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G.A.Hansen
MOOG-ACT IGV
CONTROL-PDVSA
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Safety
Perform the necessary task assessments
prior to starting the job based on the site
condition in order to perform your task in a
safe manor.
Save (upload) the original as installed
software prior to performing any changes or
calibration.
Remember to always compare your finalwork for AFI’s etc.
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Setup-Calibration
Implemented the control changes to allow for active guide vane control, in turn up rating a
current Mars 90 to a Mars 100 configuration. This initialed modifying the current control
Moog Servo System typically utilized for surge avoidance 80%-92% Ngp_Corr to an active
control varying the position through the operating range > 92% Ngp_Corr based on full
load.
Setup-Calibration
The calibration of the control needs to be performed in two steps.
1. The first being a static verification of both the on skid components and software constants.
2.Operational trimming of the full load position based on overall performance parameters.
To perform this function a copy of the test report is required
This outline is not going to get into specific calculations utilized to determine the number of
bits for a specific position due to the scaling conversion etc for the Moog control. However
this will serve as a straightforward means to properly setup and determine thefunctionality of the control. Service Bulletin 8.6/106B should be used as a reference only for
this control setup
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INITIAL CONSTANTS IGV
Initial Constants Settings –Typical Moog Actuator
RED – indicates a fixed constant, Blue – indicates variable constant. F13:551, GVAG_CLIM = -45 Minimum limit closed position
F13:548, GVAG_OFST = 0 IGV angle offset (bias to normal schedule)
F13:552, GVAG_INTM = -4 IGV intermediate set point
F13:553, GVAG_FULOP = 2.5 Deg full open limit
F13:555, GVDRIZCNT = -3662.00 Approximate zero count
F13:559, GVAG_INTH = 0.8 (needs to be set at –
2.0 during initial setup) F13:162, GVPSTNIPGN = 1.2 Utilized to trim the control linearity (position verses feedback) (0.5-
1.5) Feedback gain.
F13:163, GVPSIPOFST = 0 for this application the setting will be 0
F13:165, GVOVDSLPE = 1.67 Ngp IGV over ride gain
F13:166, GVCLOSELMT = 3.6 Representative VDC closed limit
F13:167, GVOPENLMT = -3.6 Representative VDC open limit
F13:168, GVDRIVGAIN = 0.5 Utilized for control stability (0.3-1.0)
F13:169, GVDRIVOFST = .10 Offsets the output control to the actuator
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Standard Match Temp IGV
Verify that Ngp_Corr is being
calculated correctly in file 89 and
make sure 59º is utilized in the
standard temp calculation (not 80
or 122 etc). Standard day temp is
defined to be 59 deg at sea level.
Remember that Engine Match is a
function of the nozzle shape notambient temp.
A consequence of changing the
IGV setting is a different airflow,
different T3, and different pressure
ratio.
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Signal Conditioner-Actuator Cal
Step-1
o The control is a closed loop system, +10 volt output signal address (N??) through a
voltage/current converter (Z230) –50/50mA to the servo-controller (pilot valve) located just
under the forward engine support. The control feed back is an iatrical part of the singleMoog actuator containing the (LVDT) Liner Variable Differential Transformer through a
signal conditioner (Z339) +3.6 FB signal through input address (N??)
o At this point verification of the Signal Conditioner (Z339) and mechanical position of the
Moog Actuator relative to the voltage FB signal needs to be performed. This task needs to
be performed at the unit and there are several ways to accomplish this including the
procedure listed within SB8-6-106B.
o 1. Follow the procedure listed in SB8-6-106B, however tedious.
o 2. Move the guide vanes manually, which will require the actuator lube lines be removed. Make sure
both the AC and DC lube pumps are isolated (tagged out) and the engine has completed the 4hr
post lube.
o 3. Within the logic set both the min closed –45º and 0º FB-position through the logic.
o a. The engine will need to be placed in the TEST CRANK mode in order to build hydraulic pressure.o b. Very the guide vanes between – 45 and 0 by entering a bit count within the output address N??
(typically 215 bits corresponds to – 45 and –3660 bits corresponds to 0) on the Mars engine
degree angle plat located at the engine. Verify that the corresponding feed back signal on
terminals 7 & 8 of the signal conditioner are within limits (- 45 = 3.6VDC and 0 = -3.6VDC)
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Signal Conditioner-Actuator Cal
Step-1
Signal Conditioner
OFFSET-ZERO
OUTPUT-SPAN
7 8
1. Move the IGV arm to – 22.5°,
adjust the OFFSET- ZERO.
2. Move the IGV arm between
– 45° (+3.6) min and 0° (-3.6),
adjust the OUTPUT-SPAN
+5
-5
0V
Deg-Angle
– 22.5°
Zero Offset
Output Span
-3.6
+3.6
On Eng Adjustment
Max Actuator
Exstention
– 45° 0
Servo Controller InPt Cont Sig
FB Sig
LVDT
E i C k V ifi i
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Engine Crank Verification
Step-2
The next step in the IGV control
verification will be performed during an
engine crank cycle, it’s best to have the
engine oil as close to operating
temperature as possible however not
imperative
.
1. Go on line with field programming terminal
to file 145 and set the Ngp_Corr to 80%
2. With the engine Ready Light illuminated
perform a test crank.
3. Drive the IGV’s fully open and closed
utilizing the GVOPENLMT (-4.4 or –3.6 =
OPEN) (+3.6 = Closed).
4. Utilize SB8.6/106B section 2.15-2.15.4 in
order to establish a new position gain.
Whatever number is placed in the
GVOPENLMT will drive the IVG’s. Record
the following feedback signal within the
program 145:9
a. Fully open voltage (?) -4.4 to drive open
b. Fully closed voltage (?) +3.6 to drive closed
c. Position –40, V-40 (?) Increase till –40
d. Position –5, V-5 (?) Increase till -5
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Guide Vane Pos Gain Corr
Step 2
Place the initial calculated GVPSTNIPGN from index (4) into F13:162
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Logic AFI Ngp_Corr
Move back to file 145 and
locate rung 145:10 or the
rung that drives the full
open position during a
crank and place an AFIinstruction. This rung
moves the IGV to the full
open position during an
test crank.
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Engine IGV Tracking Verification
Step 2
• Set F13:548 (GVAG_OFFST)= 0, CRANK and
adjust the Ngp_Corr per the listed scale and
note both the calculated schedule (GVAG_SCH)
and feedback (GV_DEG) along with verifying
the angle scale located on the engine. Adjust
Kval (F13:162, GVPSTNIPGN) again if needed in
order to trim the feedback and bring it in line
with the actual position.
• During the process of verifying both the controland feedback signals it’s important to make
sure the actual guide vane position is stable at
the engine. If the IGV’s are fluctuating for a
specific output adjust F13:168, GVDRIVGAIN
(.4-.6 seems to work well) however is site
specific and may need to be readjusted once
the engine is operational depending on the lube
oil temperature during the testing phase.
F13:169, GVDRIVOFST can be left at (.10), this
will effect the position relative to the output
signal.
IGV ANGLE
-45 -45 -37.5 -30 -22.5 -15 -7.5 00
80 82 84 86 88 90 92
-100
-50
0
50
100
Angle
N g p
_ C o r r
Angle
Ngp_Corr
Angle -45 -45 -37.5 -30 -22.5 -15 -7.5 0
Ngp_Corr 0 80 82 84 86 88 90 92
1 2 3 4 5 6 7 8
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Engine IGV Tracking Verification
Step 2
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IGV PT Over Ride Control
Step 2
The final step in the static test
is to verify the PT over ride
function.
AFI the Npt_Speed (F8:123)CPT instruction in file 101 so
the data can be manually
increased.
Increase Ngp_Speed >102 and
verify that the calculated
GVPSIN_SCH drives the IGVclosed based on the
PTOVERDSLOP
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Performance Issues
Low NGP, Early T5 Topping, and Low PCD
• Compressor Fouling-Dirt etc, Wash. A fouled compressor will have a loss in
airflow and efficiency.
• Bleed Valve Leak-Verify the bleed valve is not leaking ( Field certified Spit
Test)• External Compressor Leak- Feel around the flanges (using gloves) for
excessive air leaks (max 6 inch)
• Low NPT – check speed against optimum (EngPerf)
• Turbine Rub – Borescope
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Operating Point
Step 3
Requires packageinstrumentation T1, Ngp, NPT,
T5, IGV angle
Requires GTPERF or
ENGPERF5 and PIPELINE
(Gas Compressors) for Analysis
GVAG_OFFST originally set at 0
is adjusted to optimize the fullload performance.