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Table of Contents:
I designed the Diesel
Generator Control Panel (DGCP) used on the new USS Virginia
SSN-774
Submarine.
The Navy has generously posted detailed photos of it!
Graphics:
Many of the photos are high resolution and may be too big for your screen unless
automatic image resizing is enabled.
Do This --- Control Panel > Internet Options > the tab called Advanced > Multimedia >
CHECK Enable Automatic Image Resizing
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Ship
Control on Virginia, Seawolf, & Ohio
Before we get into the DGCP, it is interesting to compare the Ship Control
Stations on different class of submarines.
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Compare DGCPs on SSN Virginia; SSN Seawolf; USS Sturgeon
- These photos are shown Left-To-Right as
Newest-To-Oldest, approximately to scale.
- Left:
USS Virginia SSN-774 DGCP
- Middle: USS Seawolf SSN-21 DGCP.
Note the 40 to 50 compact,
narrow Weschler Bowmar electronic
bargraph meters and other gauges.
-
Right: USS Sturgeon DGCP (from Bubblehead's blog, see link at bottom).
-
The immediate predecessors of the Virginia DGCP are the wide, massive
Seawolf DGCP (shown below), and the tall, narrow Ohio DGCP (not shown
below), which do not have flat panel displays.
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DGCP on
Virginia
These photos are dated August 2004 taken
aboard Virginia during the pre-commisioning unit (PCU) trials. These U.S.
Navy photos were taken by Journalist 1st Class James Pinsky.
On his blog, a retired submarine officer
nicknamed Bubblehead referred to my design as as
"Not your Grandpa's Diesel Gageboard", let's see what he meant:
General Remarks on
photos 003, 012, 344:
- I refer to the above photos using the last 3 numbers
in the filenames, namely 003 and 012 and 344.
- These are excellent photos of the DGCP. In photo
003, the diesel generator set is running, the selected HMI
is the graphical piping "System" mimic (detailed in 344), the View
Readouts All option is selected, most of the instrumentation appears to be
operating properly, and most features on the front of the cabinet are
visible. In photo 012 we see how the engineer uses the trackball to select
options on the display panel.
- What's a diesel doing on a modern sub, you may ask. Virginia is of course a nuclear powered vessel, and,
like all nuclear subs, has an emergency diesel generator onboard for backup power generation.
The design details associated with the diesel systems and electrical power
generators are demonstrated by these Navy photos, and by the Technical Manual whose link appears at the bottom of this page (Naval
Ship Tech Manual - Electric Power Generators and Conversion Equipment).
- I'm thrilled to discover that these detailed
photos of my panel are posted, unclassified, public domain
(www.navy.mil/privacy.html) on the
Internet. I assumed I would never see the final product
after I left EB. I wrote this web page for my own pleasure, out of
pride for how it worked out, and as a tribute to the challenging and
productive years I spent working at Electric Boat. If you are a
student of engine mechanics or human-machine interface design or hardware
integration, or are just curious about the world around you, I hope you
enjoy learning about this little project of mine.
- The screen descriptions, below, are very detailed.
It will be interesting reading for those who like to "look under the
hood". It will be helpful if you make a printout of the 3 photos to
follow along as you read.
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Photo 003
- Viewpoint. We are looking aft
starboard. The DGCP is on the port side of the DG set. The DG set is
mounted in the submarine "backwards", with the generator forward of the
engine, as shown on the HMI. Facing the DGCP, the generator is to the left
of the engine. The DGCP is a refrigerator-size consolidated
control and monitoring panel for the emergency diesel generator. The two smaller enclosures
to the right are the Voltage Regulator and something else I
can't remember.
- HMI. The HMI software application is
Wonderware FactorySuite 2000 Intouch WindowViewer, running on Windows NT. Wonderware
is a very flexible, easy to use, somewhat expensive HMI/SCADA development
program. I also considered using ICAS, a, condition based monitoring program
(NAVSEA Philadelphia is the ICAS Lifecycle Manager), but Wonderware has a
multitude of HMI design tools that ICAS lacks. Caterpillar also makes
engine-monitoring software, which can be run on a laptop for
troubleshooting and maintenance, but when you use that you only see the
sensors that come with the DG set, not the HM&E ships sensors that hook up
to the DG set.
- The crewman (sitting) is using
a ships notebook computer, perhaps running the EngineVision software
serially linked to the Electronic Control Module (ECM) on the Caterpillar
Series 3512B turbocharged V-12 diesel engine. Virginia is the first
submarine to use a commercial diesel engine. Reports are that the crew
is very pleased with the rapid-start Caterpillar engine. Look very closely at the
bottom of the HMI and you will see "EVIM OK", indicating that the serial
interface to the EngineVision Interface Module is OK. The Intergraph computer
communicates using a simple custom message structure over RS-232 serial to
the EVIM. The TAL Technologies Winwedge software application moves the
incoming serial datastream to Windows DDE memory space, where Wonderware
can directly read it.
- From the top left,
there is a Barco ruggedized 20" RFD-251S Liquid Crystal Display (LCD), and the
Dial Telephone. The grab handles on the Barco LCD make it look a little
bit like a microwave oven. Compare the full-sized photos of the DGCP with
the SCS and you will see that they use the same Barco LCD. The LCD on the
SCS is rotated 90° because its designers chose to use the "portrait"
orientation. The dial phone has a jack for a boom-mike
headset instead of having a built-in handset.
- Below, sound powered telephone jacks JA and 2JV,
speaker cutout switch, loudspeaker.
- Below, collision alarm (red), voltage regulator
control transfer switch. If you're wondering why I put the voltage
regulator remote controls on the DGCP when the voltage regulator itself is
right next to it, it is because the local controls inside the voltage regulator
are very small and not readily accessible; that was never intended to be the place where the operator
controlled voltage. The DGCP is designed to be the remote-manual control
for it.
- Right, behind a protective Plexiglas shield with
finger holes to help prevent inadvertent operation, the DG Set control and
indication panel consisting of Staco pushbuttons and indicator lamps. This
part of the DGCP is similar to the features on the electric plant control
panel (EPCP) in the aft end. From here the engineer can do things like
start and stop the DG, adjust its output voltage, and control the space
and jacket water heaters.
- Right, the recess is for the Q70 style trackball. The Barco LCD is not a touchscreen. I avoided a touchscreen because when
you are working in the AMR your hands may get dirty and that would make
the screen look messy.
- Below, a pull-out keyboard tray (shown stowed). Only
needed for maintenance and configuration.
- Below, a rackmount Intergraph TDR-3000 ruggedized
computer. Look very closely and you will see the oval Intergraph logo. I
leveraged off the use of Intergraph ruggedized PC's on Smartship.
- Below (not show) a small power distribution panel,
and a hinged front door for two shelves of Opto22 SNAP IO B3000-ENET data
acquisition modules. Look very closely at the bottom of the HMI and you
will see "Top B3000 OK" and "Bottom B3000 OK". The Intergraph computer
communicates using Modbus over Ethernet to the B3000's. Wonderware comes
with a device driver for Modbus over Ethernet. My design decisions were
happening at the same time that the HMI/SCADA industry was rapidly
transitioning from proprietary interface protocols to open standards using
TCP/IP. If I were doing this design today, I would probably use Profibus-DP
or Profinet.
- Inside, power supplies, relay boards, a hub, and
miscellaneous hardware.
- The HMI shows the EDG running. All of the following
values are displayed. Engine speed is about 1800 RPM. Engine cylinder
temperatures are around 1000 F, and exhaust air is 157 F after being
cooled by the seawater mist injection. The ambient compartment pressure
is 0.2 inches of mercury vacuum because the engine is drawing ambient air.
All three exhaust valves (isolation, backup and hull), all three induction
valves (backup, hull, and head), and all three seawater valves are open,
of course.
- Output voltage is about 700 volts DC and output power is 921
kilowatts. Virginia is the first submarine to have a DC voltage bus. Why does the EDG
set output 700 DC, you may ask. Because Virginia has a 700 VDC
distribution system (no frequency-sync of power sources needed). There are
lots of invertors throughout the ship to convert to whatever power
is needed. The DDG-1000 Zumwalt Destroyer design that I am now working on at Raytheon also has a DC bus.
Unlike SSN Virginia, DDG Zumwalt is a true Integrated Fight Through Power
IFTP system because it is electric-drive. There is as yet no such thing as
an American motor-driven nuclear-powered submarine. The electric-drive SSN
of the future will be far stealthier than today's mechanical-shaft-driven
subs, because electric-drive physically decouples the noisy nuclear steam
plant from the propeller shaft, reducing signature.
- There are 16937 gallons of fuel remaining in the
normal fuel oil tank.
- You can trace the path of heat flow through the
coolers and heat exchanges on the lube oil (yellow), fuel oil (yellow),
ventilation/exhaust (tan) , freshwater (blue), and seawater (green)
systems to see how much heat is added or removed by each equipment. The
HMI color code matches with valve handwheel paint color scheme. The HMI
does not show every valve and equipment in these piping systems; only the
parts of the system that are instrumented are shown.
- There are tiny nicks and scrapes on the Barco
handles, which give you an idea how rough this environment is.
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Photo 012
- The engineer reaches into the recess to move the
trackball for the LCD.
- The LCD is displaying the "datasheet" view. This
view contains the same data as the "system" piping view above, in the
format of an instrument list instead of the format of a piping mimic. The operator can use the display format he is most comfortable with.
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Photo 344
- The DGCPs (or equivalent equipment) on previous
submarine classes, such as Los Angeles (SSN-688, about 60 boats), Ohio (SSBN-726,
about 18 boats), and Seawolf (SSN, 3 boats), have individual vertical
bargraph meters and dials to provide indication and monitoring of
instrumentation. On Virginia, the DGCP design goes high-tech with the use
of a flat panel display, providing virtually all indication and
monitoring (not control). The HMI may look "busy" at first, but the operator can
simplify it by selecting different options for which readouts are
displayed and which readouts are hidden. I'll be honest with you, this
flat panel display is a glorified bargraph meter. Count the quantity
of numeric readouts and valve-position icons, it comes out to around 80
plus admin-buttons. It would have taken up a lot more space than an LCD to
foundate 80 bargraph meters and what-not on a steel cabinet. That's
why Seawolf's DGCP is so huge (wish I had a picture to share).
- Something operators like about bargraph meters is
that they can make quick status assessments by merely glancing at the
heights of the bargraphs, without considering the numeric values. The HMI
accomplishes the same thing by using dynamic font color coding (green
Good, yellow Warning, red Bad). The color coding matters when the engine
is running. For most readouts, the color coding does not mean anything
when the enging is not running.
- This HMI describes all major elements of the
auxiliary systems that interface with the DG Set.
- The NFO tank is down to 16690 gallons, so this
photo was taken after the engine had been running for awhile (see previous
picture), and the
cylinders have cooled down.
- There is an option button labeled Instrument Numbers
that displays the instrument number of each readout in a small font. This
option is shown turned off (otherwise the HMI would look even busier). The
operator knows what a readout is for by noting its location within the
context of the piping mimic.
- The diesel seawater (DSW) pump and diesel freshwater
(DFW) pump icons represent fluid centrifugal pumps. The fuel oil (FO) pump
and fuel oil transfer (FO Xfer) pump icons represent axial pumps.
- The bottom right hand corner shown that the engine
shut down due to high exhaust backpressure, which means that the one of
the exhaust valves was shut, which tripped a pressure switch sensing
exhaust gas pressure (IC Circuit 2SN).
- The 8H switchboard breaker is shown open (the bar is
not aligned with the bus).
- The DSW pump valve DSW-1 valve is shown closed (the
bar is not aligned with the pipe).
- It is interesting to note that an "open" electrical
breaker looks same as a "closed" piping valve. The graphical
representation of an electrical single-pole switch, when drawn "open",
represents the absence of a continuity-path for the flow of
electronics. The graphical representation of a valve, when drawn "open",
represents the absence of a restriction to the flow of a liquid or
gas. I like to quiz mechanical engineers by asking them which word they
use to describe the 8H breaker symbol, shown - they usually say closed :-)
- Along the top, the long flat rectangle, filled with
diagonal hatch marks, represents the pressure hull. Seawater (green),
fresh induction air (tan), and exhaust air (tan) penetrates the pressure
hull boundary. The snorkel head valve VH-1, shown outside the pressure
hull, is the flapper that uses water-sensing electrodes to automatically
slam shut when waves lap over the hull while running the engine. In a high
sea state this valve will open and close quickly and frequently. If
excessive wave action causes it to close for a long time, the ambient
compartment pressure switches will sense a low vacuum pressure and
automatically shut down the engine. Crewman will probably feel their ears
pop. If the head valve electrodes sense water, and the head valve does not
successfully close within a certain time period (maybe a whale is stuck in
the poppet valve), the induction hull and backup valves automatically
close to prevent flooding (IC Circuit 1SN).
- These fancy new flat-panel-display based
control-and-indication screens on Virginia (Ship Control, EPCP, DGCP,
others) went through extensive HMI Fleet Reviews. I remember presenting
this design to a crowded room full of NAVSEA reps and Chief Engineers in
February 1998. We captured hundreds of comments and incorporated dozens of
suggestions to arrive at this design. The important thing to note is that smart, robust HMI design is being taken very seriously as it's used
more and more. Years ago an HMI requirements spec often said "the HMI must
have an easy to use look-and-feel". Today there is a large body of
knowledge of what constitutes good HMI design.
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Generator on Virginia
I'm an electrical
guy, so this page wouldn't be complete without a discussion about what the
diesel is actually on the ship for, to drive the generator. Virginia has a
very compact custom generator.
The generator that is attached to the engine is custom.
The generator is an inverted synchronous AC generator with a built-in
power rectifier.
The term inverted is used because the
Main Stator Coil is the Armature. The rotating magnetic field is in
the Main Stator, also called inside-out.
The term synchronous AC generator is used because the following equality
applies:
Calculate the rotational speed, where
the Main Rotor has P = 6 (pairs of) poles, and runs at 90 Hz.
Synchronous speed NS = 1800 RPM. Number of
phases q = 6 x 2 = 12.
The output frequency can be increased by increasing the RPM's, or add more
poles.
1.
Cylindrical. For high-speed, 2 or
4 pole, quiet, balanced, low winding losses.
2.
Salient-pole.
For low and medium speed. Have outward projecting laminated poles.
This generator has salient-pole rotors.
The
rotor & stator have the same number of
poles.
The Rotor winding carries DC, to produce constant flux per pole.
DIESEL ENGINE.
The Diesel Engine turns the shaft. The shaft is part of the rotor inside
the generator housing.
GENERATOR HOUSING
Generator Housing contains rotor and stator.
Rotor windings include PMA rotor, exciter rotor, and main rotor.
Rotor windings are surrounded by stator housing.
Stator windings include PMA stator, exciter stator, and main stator.
I have not found a
concise description of this type of generator on the Internet, so I'll
describe it below, in sequence.
PMA
(stationary armature, rotating field magnets)
The purpose of the Permanent Magnet Alternator is to create a rotating
magnetic field to generate enough power to flash the exciter field.
PMA rotor (12-pole Lundell) turns, sets up rotating magnetic field (the
permanent magnets rotate).
PMA field magnets rotate
inside stationary armature, interaction induces EMF in PMA stator.
PMA stator winding 3 phase 180Hz 150VAC output is hooked up to Voltage
Regulator input.
Voltage Regulator regulates and rectifies power.
Voltage Regulator AC output is rectified and the DC output is hooked up to exciter stator windings.
The magnets inside a PMA are
extremely powerful, and dangerous if you have to handle them.
EXCITER
(stationary field winding, rotating armature)
The purpose of the
Exciter is to provide the Main Salient Poles with DC power to create a
rotating magnetic field.
Exciter stator winding is powered with DC, sets up a stationary magnetic
field.
Exciter armature rotates inside stationary field winding, interaction induces EMF in
Exciter rotor.
Exciter rotor (16 pole Exciter Field Winding armature) 3 phase 240Hz AC
output is hooked to a full-wave bridge rectifier.
The rectifier is also located on the rotor.
Rectifier DC output is hooked up to main rotor.
MAIN POLES
(stationary armature, rotating field winding)
Main rotor (the Field Winding consists of 6 Main Salient Poles) turns at
1800RPM 90Hz, sets up a rotating DC magnetic field.
Main field winding rotates inside stationary armature, interaction induces EMF
in Main stator.
Main stator (4 of 3 Phase Windings in Main Stator Coil Armature) AC
output is hooked up to Power Rectifier.
Power Rectifier outputs 700 VDC which is delivered to the ship's
electric plant.
Summary
PMA Rotor > PMA Stator > VR >
Exciter Stator > Exciter Rotor > Rectifier
>
Main Rotor > Main Stator > Rectifier > Ship's DC
buss.
-
Slip. If the rotor is revolving at exactly the same speed as the
magnetic field, no currents will be induced in it, and hence the rotor
should not turn at a synchronous speed. In operation the speeds of
rotation of the rotor and the field differ by about 2 to 5 percent. This
speed difference is known as slip.
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