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The Power in
Electrical Safety
Integrity Management in Subsea Systems
Subsea Expo 2016
2BENDER > Presentation Theme
A big idea,
which still drives us to this day.
Walther Bender‘s vision over 70
years ago: comprehensive
protection against the dangers of
electrical current.
3BENDER > Presentation Theme
Bender Group – Offshore Experience and Project Scope
Bender Americas
• Chevron Bigfoot
• Shell Olympus
• BP/Hess – Tubular Bells
• Many more projects on a global level
• Extensive experience monitoring subsea umbilicals
4BENDER > Presentation Theme 4
What is “Asset Integrity Management”?
• The ability of an asset to perform its
required function effectively and efficiently
whilst protecting health, safety and the
environment.
• The means of ensuring that the people,
systems, processes, and resources that
deliver integrity are in place, in use and
will perform when required over the whole
lifecycle of the asset.
• The challenge to management is to
ensure that the integrity of engineered
systems – for instance, offshore
structures, ships, pipelines and process
systems – is maintained throughout the
anticipated service life.
Bureau Veritas, Asset Integrity Management
5BENDER > Presentation Theme 5
Risks Associated with Poor Integrity Management
• Loss of Life and Injury to Personnel
• Environmental Damage
• NPT – System Downtime and Production
Losses
*Non-Productive Time accounts for substantial losses in
output and revenue in the global offshore industry. NPT is
estimated to cost upwards of $400-$500 million USD
annually. Drilling Rigs and Automation, 2015
6BENDER > Presentation Theme
What is Insulation Monitoring (Offshore and Subsea)?
• Monitoring topside, hull, and subsea networks
for unintentional current leakage and loss of
resistance to ground.
• This term typically refers to unearthed or
“floating” electrical systems, such as would be
encountered on subsea umbilicals.
7BENDER > Presentation Theme
Insulation Monitoring as Integrity Management
• Allows for the detection and prediction
of decreasing insulation resistance in
offshore and subsea assets.
• Advanced techniques allow for the
location of fault conditions, which
facilitates corrective maintenance.
• Trending of ohmic values over a set
period of time enables operators to
determine activities that contribute to
hazardous conditions and equipment
failures.
8BENDER > Presentation Theme
Consequences of Poor Insulation Monitoring
• Failure of critical electrical components and systems.
• Unexpected NPT and loss of production revenues.
• A “blind spot” in determining umbilical damage, as well
as contributing factors.
• Failure of electrical systems that protect personnel and
provide environmental protection (including BOP, Hull
electrical distribution networks, and topside equipment*).
*Equipment such as blow-out
preventers (BOPs) and top drives can account
for 51% - 75% of all equipment related NPT.- Jeff Swain, Chevron Rig Systems
9BENDER > Presentation Theme
Potential Causes of Low IR – “Tin Whiskers”
• Tin whiskers pose a serious reliability risk to
electronic assemblies.
• Stable short circuits in low voltage, high
impedance circuits.
• Whiskers or parts of whiskers may break loose
and bridge isolated conductors.
• Many sudden failures and intermittent problems
are associated with tin whiskers because of their
ability to short closely spaced electronic circuits.
10BENDER > Presentation Theme
Potential Causes of Low IR – Abrasion and Device Failure
11BENDER > Presentation Theme
Potential Causes of Low IR - Water and Electrical “Trees”
• “Treeing” is an electrical pre-
breakdown phenomenon in solid
insulation.
• A damaging process due to
partial discharges and
progresses through the stressed
dielectric insulation, in a path
resembling the branches of a
tree.
• Treeing of solid high-voltage
cable insulation is a common
breakdown mechanism and
source of electrical faults in
subsea umbilical cables.
Water trees begin as a microscopic
region near a defect. They then grow
under the continued presence of a high
electrical field and water. Water trees
may eventually grow to the point where
they bridge the outer isolative layer to
the center high voltage conductor,
leading to complete electrical failure at
that point.
12BENDER > Presentation Theme
Passive Resistance Monitoring Technique
13BENDER > Presentation Theme
Passive Resistance Monitoring Technique
Limitations/Deficiencies:
• Inability to detect a symmetrical ground fault, as opposed to faults on a single phase.
• Lack of predictive capability in determining the potential for equipment failure.
• No indication of the severity of a fault condition in terms of insulation resistance.
14BENDER > Presentation Theme
Active Insulation Resistance Measurement
• Typically involves the injection of
low-level pulse current into an
electrical system.
• If a ground fault occurs, the
measuring circuit is closed and a
small measuring current will flow.
• Return of the measuring pulse is
evaluated to determine system
insulation resistance levels.
• Proactive approach to resistance
measurement in topside and subsea
electrical systems.
Measuring current is proportional to the
insulation resistance (the magnitude of the
ground fault), and is evaluated by the detector.
15BENDER > Presentation Theme 15
Active Measurement of Insulation Resistance - Benefits
• Detection of symmetrical and
asymmetrical ground faults.
• Indication of fault severity as
expressed via a resistive value.
• Allows for trending of drops in
insulation resistance, as well as the
comparison of such events against
offshore and subsea operational
activities, in order to determine
precipitating factors
• Can provide early-warning to
facilitate preventative and corrective
maintenance actions by operators
16BENDER > Presentation Theme
Importance of “real-world” data and trending
• Best practice and due-diligence dictate the
replacement of components whose
structural and functional integrity are high
risk.
• A lack of recorded data means equipment
failure can take place without preparation
on the part of the operator.
• Measurement trending allows for the
operator to identify hazardous practices
and take corrective action, while benefiting
from advance warning in planning NPT for
maintenance procedures.
• A true understanding of electrical isolation
values is VITAL to integrity management.
17BENDER > Presentation Theme
Additional Electrical Integrity Management Techniques
• Power Quality Management – including
analysis of Frequency, Phase Sequence,
Under/Over-Voltage, Under/Over-Current,
Power Factor, Harmonics, and L/G Voltage
Imbalance.
• Fixed and portable ground fault location
systems.
• Offline monitoring of critical electrical
systems (including fire pump motors)
• System integrity evaluations by qualified
consultants and subsea experts.
• Standardized procedures for the utilization of
ground fault data when coordinating field
replacement of critical equipment.
18BENDER > Presentation Theme
What does the future hold for subsea fault monitoring?
• Fault detection and location on subsea
“trees” and electrical network installed
below the waterline.
• More accurate fault location
capabilities, beyond the feeder level.
• Remote data-logging and assistance
via VPN.
• Fault location on active umbilicals via
the use of Spread Spectrum TDR
Technology.
19BENDER > Presentation Theme
Questions and Comments?
20BENDER > Presentation Theme
The presentation, its content, pictures and drawings are protected by copyright law. Duplication, translation, microfilming and transfer into any electronic systems, especially for commercial purposes is not allowed and subject to approval by the issuer. We do not assume any responsibilty and liabilty forfaulty or missing content. All data is based on manufacturers‘ information. All logos and product descriptions are registerered trademarks of therespective manufacturer.
Bender Inc.
420 Eagleview Blvd.
Exton, PA 19341
www.bender.org
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