Petrochemical
Industrial Complex - South Korea:
The Forensic Services Group was
appointed when a suspected instrument and control
problem had caused serious equipment damage as well
as a substantial business interruption loss at a
Korean petrochemical reactor facility. FSG
interviewed eye witnesses, analyzed the control
system schematic diagrams, examined the electronic
control modules & computers which enabled us to
uncover the
cause of the accident.
|
Control room (left)
- Systems electronics
(right) ...
|
Key questions &
answers:
 |
Why didn't oil pressure failure shut
down system? |
|
Why didn't emergency stop commands
function? |
|
Why didn't the backup computer come
on-line? |
|
No failure of oil pump or backup
computer. |
|
No failure of electronic circuit boards.
|
|
PLC Output Module latches up & inhibits
control signals. |
|
Equipment unable to be shut down
automatically. |
|
Steam Turbine
Power Generation System - Philippines:
A steam turbine, driving a 30 mega-watt
generator, went into an over-speed condition and flew
apart in the Philippines. After turbine specialists had
examined the damaged turbine, indications were pointing
to a control system problem rather than a mechanical
failure that initiated the accident. It was at this point that FSG was called in to
analyze the instrumentation & control system and look
for answers. We were successful in determining the cause
of the accident and then able to offer suggestions for preventing
similar occurrences in the future.
|
Control room panel (left)
System schematic diagram (right)
...
|
Key questions &
answers:
|
Why didn't over-speed conditions shut
down system? |
|
Why didn't emergency stop commands
function? |
|
Why weren't operators notified of
emergency? |
|
No failure of electronic circuit boards.
|
|
No failure of communication
sent to
operator. |
|
Speed transducer fails.
|
|
System logic inhibits emergency
shutdown. |
|
Laser Engraver
System - Malaysia:
Intermittent problems occurring within
an 800-watt CO2 laser engraving system caused
costly downtime resulting in loss of production together
with
extensive troubleshooting & maintenance. The
Forensic Services Group were called in to perform an
independent analysis of the control system. We were
asked to confirm previous troubleshooting and repairs
done by the manufacturer's service engineers and to
determine the cause of equipment failure. FSG was able
to successfully determine the cause of the failure and
recommend preventative measures to avoid similar future
situations from arising.
|
Laser (left)
- Electronic control PCB (right)
...
|
Key questions &
answers:
|
Why did machine stop intermittently?
|
|
Why did laser power drop to low levels?
|
|
Why was there intermittent
communications? |
|
Replacement electronic circuit boards
didn't fix problems. |
|
No problem with computer or interface
electronics. |
|
Damaged
conductor found on printed
circuit board. |
|
System interlock
failure - defective component.
|
|
Cold Rolling Steel Mill Systems -
worldwide:
The Forensic Services Group has been called on to analyze system
control problems associated with cold rolling mills
located in steel manufacturing plants throughout Asia,
Europe, South America and the USA.
Most of the work has involved Sendzimir and 4-Hi
machines that were built in the USA, China, Europe & Japan.
|
The above
photos - Steel manufacturing plants in China
(left) & Korea (right) ...
|
Instrumentation & Control System
Analysis:
|
X-ray,
Radiation and contact gauge
troubleshooting. |
|
Automatic Gauge Control (AGC) system problems.
|
|
Intermittent & electrical grounding
troubleshooting
|
|
Hydraulic screw-down tuning &
calibration. |
|
Computer troubleshooting and repair.
|
|
Installation and start-up problems.
|
|
Wafer Conveyor
Transport System in Semiconductor IC Chip Facility -
Taiwan:
A major Taiwanese semiconductor IC chip
manufacturer experienced problems during the
installation & start-up of a wafer conveyor transport
system. The conveyor is an automatic and multiplexed
transport "highway" elevated near ceiling level to move
unfinished semiconductor wafers as they are processed
into finished product. On several occasions, accidents
involving collisions between wafer carriers resulted in
expensive semiconductor loss. FSG was requested to
analyze the system and come up with answers for the
cause of accidents. We were able to work with the
manufacturer and start-up engineers to define and
explain the reasons for accidents.
|
Photos show elevated conveyor
and equipment to process the
semiconductor wafers ...
|
Key questions &
answers:
|
Why does conveyor system shut down
intermittently? |
|
Why did the robotic arm damage a wafer
cassette? |
|
Why did a wafer cassette crash during
transport? |
|
Why was the wrong wafer cassette
received at a tool? |
|
Loose wire found on transducer
causes problem. |
|
Incorrect coupling used on robotic arm.
|
|
Defective transducer causes wafer
cassette crash. |
|
Software modification needed to correct
conveyor speed. |
|
Loose screw on robotic arm causes wafer
mishandling. |
|
PABX Telephone System at
University - Hong Kong:
After a digital telephone exchange
system was installed to replace its older analog
version, a series of un-explained failures began to
occur during recent thunder storms. While it may not
appear unusual for failures and damage to occur from
lightning during an electrical storm, the original
analog PABX system did not experience these frequent
failures. FSG was called in to probe the digital PABX
system and come up with answers for the failures ...and
make recommendations to solve the problem. We were
successful in pin-pointing several problem areas.
|
MDF panel (left) Poor Wire Routing (right)
...
|
Key questions &
answers:
|
Why does the digital PABX system fail
intermittently? |
|
Why was the old analog PABX system more
reliable? |
|
Why do electrical storms damage the new
PABX? |
|
What is the best PABX protection against
lightning? |
|
Loose wire connections on earth-ground
buss bar. |
|
Earth-ground wires improperly installed.
|
|
PABX cabinets not properly
earth-grounded. |
|
Excessive distance between PABX &
earth-ground. |
|
Power wires & signal wiring not
separated in trench. |
|
Golf Course
Irrigation System - Hong Kong:
Several recent thunder storms caused
damage to a golf course irrigation system resulting in
damage to expensive electronic equipment. Although it
might be expected to occasionally experience some
damage, this particular golf course was equipped with
advanced storm detection equipment to prevent such
losses. FSG was appointed to find out why the storm
detection equipment was not able to protect the
irrigation system since it was designed specifically for
that task. We were able to simulate electrical storm
conditions for testing the storm detection equipment by
designing an electronic instrument and using it at the
golf course. Our results were used to prevent future
damage.
|
The above photos - Irrigation
Satellite
Stations (left) Equipment Control (right)
...
|
Key questions &
answers:
|
How can irrigation system be protected
from damage? |
|
Why does the lightning detection system
fail? |
|
How can the lightning detection system
be tested? |
|
How can lightning protection be
improved? |
|
FSG designs an instrument to test
detection system. |
|
Lightning detection system out of
calibration. |
|
One of three lightning modules is found
defective. |
|
Power line surge - responsible in
only one case. |
|
FSG suggests alternative lightning
protection methods. |
|
Paper Coating
System - Shanghai:
Initially, it was thought that a Y2K
related accident had been the cause of a failure at a
paper coating process line in China. An error in the
complex sequencing that controls the roll changing
operation had failed causing extensive damage to several
of the assemblies responsible for lifting the massive
paper rolls. FSG was called in to find out why the
accident had occurred. After a comprehensive investigation,
the cause was narrowed down to a key hydraulic servo valve
which had
received a false electrical signal that triggered the
untimely event.
|
Coating
Line (left) - Paper
Roll (right) ...
|
Key questions &
answers:
|
Why did mechanical lift-arm move?
|
|
Why was the system sequencing order
skipped? |
|
Why didn't the safety circuits work?
|
|
Why couldn't the operator over-ride the
malfunction? |
|
All safety devices could not have failed
simultaneously. |
|
Possible cause is analog output module
failure. |
|
Possible cause is proportional servo
valve failure. |
|
Multimedia
Marketing System in Shopping Mall - Hong Kong:
Alleged water damage had disabled the
audio portion of a marketing display at a prominent Hong
Kong shopping mall. FSG was called in to verify the
damage and assess the situation. After an examination of
the equipment, we were able to test and troubleshoot the
system which led to determining the exact damage and
recommending an economical repair. FSG was able to
pinpoint the actual failure and prove that the damage
was overstated.
|
Mall Area (left) Electronic Equipment
(right) ...
|
Key questions &
answers:
|
Did water really damage any of the audio
equipment? |
|
What are the symptoms of the alleged
failure? |
|
How can the audio system be tested?
|
|
FSG sets up logical troubleshooting
sequence? |
|
Section of audio isolated and FSG
pinpoints failure. |
|
Equipment was defective before alleged
water damage. |
|
Insurance claim is dropped.
|
|
Cruise Ship
Stabilizer System - Hong Kong:
Problems with a cruise ships' stabilizer
left electricians trying to figure out how to fix it.
Fsg was called in to assist the ships' electrical
technicians to troubleshoot the stabilizer control
system. After several hours of working on the closed servo
control loop, the equipment was back in operation.
|
Cruise Ship (left) -
Schematic Diagram (right) ...
|
Key questions &
answers:
|
Is stabilizer problem electrical or
mechanical? |
|
Check hydraulic proportional servo
valves. |
|
Verify electrical signals driving servo
valves. |
|
Isolate and test electrical circuit
boards. |
|
Visually check mechanical couplings &
linkages. |
|
Check calibration of electrical signals
& servo valves. |
|
