Transcript Cable Re-use for Ocean Bottom Observatories Cabled Observatory Presentation

Cable Re-use for
Ocean Bottom Observatories
Cabled Observatory
Presentation
School of Ocean and Earth Science and Technology
February 2006
Observatories on
Telecom Cables
• Think of these as “Cables of Opportunity”
• There are 35,000km of SL280 and SL560
cables being retired.
– Substantial amount of power.
– Constant-current mode.
– Essentially no dynamics in original design.
– Typically two active pairs and one spare.
Positive Aspects
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The shore station is already in place.
The cable is bought and paid for.
The cable is shored.
The cable is laid. (No risk here.)
There are still a good number of useful
years in the system.
• The most “pre-tested” cable imaginable.
Telecom Cable Power System
• The Constant-Current SL280 Cable
– Identical Loads (Repeaters)
– Constant for 20 years (ideally)
– No allowance for future expansion.
– Highly optimized for very narrow span.
• High-reliability telecom.
– The cable route is fixed.
• (Although end can be relayed.)
Adapting the SL280 Cable for
Observatories
• Observatories must co-exist with repeaters
– Must stay within known limits
• We must provide flexibility not present in
original system on the user side.
• On the other hand, we are NOT
necessarily constrained by all of the
original specifications.
– (Time to think “outside the phone-booth”)
“In and out of the Phone Booth”
• For POWER, we have to live within the
constraints of the existing PFE.
– SL is much easier than SD because the
repeaters have stiff regulators.
• For DATA TRANSPORT, PDH has vast
complexity that is 99% useless to us.
– But is there a way to eliminate or bypass it??
SL Cable Data Channel
• SL280 and SL560 cables use PDH data
format:
– VERY complex format and structure
– VERY dynamic routing
– Complex supervisory overhead
• MOST of this is not needed for
observatories.
Using Existing Format
• Need to add a Dummy Mini-TTE so that
Makaha thinks it is talking to California
• Need Frame Relay to get Ethernet into
Phone System Format.
• Most existing COTS equipment is powerhungry and not meant to fit into pressure
case.
• Again, most functions are not needed.
Reducible Complexity
Group/System Dynamics
• The dynamics are … dynamic.
– Number of observatories will hopefully grow.
– Experiments per observatory will grow.
– The dynamics of an experiment may be
unpredictable.
• The Cable PFE was designed for zero
dynamics.
Two Birds with one Stone
• High-efficiency DC-DC converters are
incompatible with a constant-current
source.
• (Heaven help us!) We have to make the
Science Community invisible to the PFE.
• The shunt regulator solves both problems
reliably and simply.
The Plan
• The Shunt Regulator is a known “must”.
• There may be a variety of ways of
designing the rest of the power circuits.
• There are standard ways that can be
adapted, or more novel and creative
techniques may be required.
• But why re-invent the wheel??
Industry Standard Configuration
HV Power Distribution
• Start with High Voltage Distribution.
– Line losses go down with square of voltage.
• Step it down with fixed-ratio transformers.
– This is the main power conversion.
– Keep complexity to a minimum.
• Do any necessary regulation at low
voltage.
– Wide-range COTS regulators available.
– Voltage variations will be well within range.
– Use REDUNDANT regulators.
Constant Current Power Distribution
• The size of the voltage drop determines
your available power.
• Step it down with fixed-ratio converters.
– This is the main power conversion.
– Keep complexity to a minimum.
• Do any necessary shunt regulation at low
voltage. (Easier, more reliable.)
• The transformer ratio will reflect a scaled
image of the shunt regulator on the
secondary side.
Simplified POWER SUPPLY Stack
Incremental Failure Tolerance
• If any one power converter module fails:
– The line voltage drops to 700V.
– There is 12.5% less secondary power.
• If seven power converter modules fail:
– The line voltage drops to 100V.
– There is only 150 Watts of secondary power.
• Nothing else changes.
Shunt Regulators
• In most shunt regulators, a single shorted
transistor can take down the whole bus.
• The shunt regulator is also incrementalfailure tolerant.
– A shorted shunt transistor only results in
wasting one increment of current.
– An open shunt transistor only decreases the
shunt capacity by one increment of current.
Power Supply Control
• Simple Rabbit 3000 microcontroller.
• Isolated voltage-to-frequency converters
monitor all significant voltages.
• Isolated Magnetoresistive-effect sensors
used for currents.
• Thermistor probes for temperatures.
• Backplane used for modular power
converters.
Rabbit 3000 Controllers
Power Module Backplane
Converter Modules
Shunt Regulators
Heat Dissipation at 1200 Watts
Testing
• Use a variety of fully dynamic loads.
• Use continuous maximum cycling with
pseudo-random pattern generator to
simulate every possible static and
transient load condition.
Dynamic Test Load
Dynamic Load Testing
Progress on Backbone
Communications
PROJECT ALOHA BACKBONE COMMUNICATIONS
JUN-05: OBTAINED AT&T TERMINAL AND REGENERATOR EQUIPMENT (NJ)
AUG-05: TESTED SL280 mini-TTE (NJ)
AUG-05: TESTED SL280 mini-TTE/SL560 REGENERATOR TANDEM (NJ)
OCT-05: COMPLETED MULDEX PROTOTYPE DESIGN
JAN-06: TESTED MULDEX PROTOTYPE AT SL280 AND SL560 RATES (NJ)
FEB-06: TESTED SL280 mini-TTE (HI)
FEB-06: TEST MULDEX PROTOTYPE FOR SL280/560 OPERATION (HI)
MAR-06: TEST MULDEX PROTOTYPE OVER SL280/560 TTE/REGEN (HI)
MAR-06: DESIGN (if required) PRODUCTION MULDEX MODEL (HI)
???-06: TEST PRODUCTION MODEL (as required) (HI)
???-06: LAB AND DEPLOYMENT INTEGRATION TEST (HI)
PROJECT ALOHA BACKBONE SUPERVISORY
SEPT-05: OBTAINED AT&T SL280 SCOUT EQUIPMENT (NJ)
OCT-05: TESTED SL280 SCOUT WITH mini-TTE (NJ)
DEC-05: MODIFIED SL280 mini-TTE FOR SL560 SUPERVISORY CARRIER (NJ)
MAR-06: TEST SL560 SUPERVISORY REGENERATOR SUPERVISION (NJ)
APR-06: MODIFY SL280 mini-TTE FOR SL560 SUPERVISORY CARRIER (HI)
???-06: TEST SL560 SUPERVISORY REGENERATOR SUPERVISION (HI) #
???-06: COMPLETE MS-EXCEL BASED ALOHA SYSTEM mini-SCOUT (NJ) ##
#: Schedule driven by transfer agreement signing.
##: The SL280 SCOUT is almost 20 years old and difficult to use. A
EXCEL version employing appropriate graphics and macros would
be much easier to use and need not reside at the Makaha Station.
We can live without this capability if necessary.
PROJECT ALOHA MAKAHA TERMINAL
SEPT-05: OBTAINED AT&T STATION DRAWINGS (NJ)
NOV-05: OBTAINED NEW ROOM LAYOUT AGREEMENT FROM AT&T (NJ)
???-06: EQUIPMENT MOVE/INSTALLATION STATION #
???-06: MODIFY AND TEST SL280-TTE AND SCOUT #
???-06: INSTALL AND TEST MULDEX WITH SL-280 TTE #
#: Schedule driven by transfer agreement signing.
Conclusions…
• The original PDH data format is complex
and is associated with high costs, long
development times and complex
hardware.
• There are few benefits which can not be
achieved by much simpler means.
• Some benefits can be much better
achieved by other means.
Conclusions…
• The technique for transporting format and
bit rate independent data over the existing
channel is highly cost effective.
• First round testing looks quite positive.
• Full testing is coming soon.
Conclusions…
• This Second Generation Power Supply
has greatly expanded operating margins.
• Modular design allows for easy testing and
easy maintenance.
• The new Shunt Regulator design has
much improved heat dissipation.
• The pseudo-random test load tests for a
wide range of operating conditions.
Conclusions…
• The basic problems of dynamic stability
and user community dynamics are
effectively controlled by the shunt
regulator.
• The power system is multiple-fault tolerant
in the critical areas and has very few
single-point failure modes.
• Rigorous system testing will weed out
infant-mortality and rare event failures.
Simplified POWER SUPPLY Stack
VOLTAGE MODE STACK