15-questions-retrofilling-transformers-fr3-insulect

insulect.com/transformer-retrofill
TOP 15 QUESTIONS
Retrofilling
transformers
with FR3 Fluid

Whyretrofillatransformer?
The motivations for power and distribution transformer retrofilling are
numerous. They range from addressing an urgent need on a single asset,
to rolling out a network-wide program with clear financial returns.
Each transformer has unique operational factors that influence the
situation such as load, asset design, age, location, and environment.
Transformer insulation: the weakest link
In many cases, the reasons relate to the cellulose insulation, since this is
the weakest link in a transformer. Cellulose insulation failure is one of the
top three reasons for a transformer failing and degradation of the
insulation (ageing) is irreversible.
Some of the most common reasons for transformer retrofilling include:
OIL QUALITY
decrease the levels of undesired
contaminants and dissolved gases
DRY OUT
reduce moisture levels in the oil
PCB CONCENTRATION
remove contaminated oil
EXTEND USEFUL LIFE
and delay replacement

When retrofilling mineral oil filled transformers
with Envirotemp FR3 natural ester fluid, there
are additional financial incentives that support
positive return on investment.
This is due to the unique capabilities of FR3 fluid and its performance in
transformers, resulting in cost savings without sacrificing reliability.
LIFE EXTENSION
significantly beyond what is
possible with mineral oil
SLOW THE AGEING RATE
and delay capital investment for
transformer replacement
INCREASE LOAD
additional load capacity within the
existing transformer footprint
OVERLOAD CAPACITY
gain increased safe overload
FIRE SAFETY
reduced risk through much higher
fire point and flash point
SAFETY COMPLIANCE
meet fire codes, insurance audits;
clearances, fire wall, deluge system
+

ENVIRONMENTAL IMPACT
minimise environmental impact
and facilitate policy compliance
SPILL REMEDIATION
simplified and less costly bio
remediation and containment
Many of our customers have financially justified FR3 natural ester fluid
retrofills based on just one of these factors. When multiple factors are
evaluated together, they can create very compelling business cases for
retrofilling with FR3.
Positivereturnoninvestment
Retrofilling mineral oil filled transformers with FR3 fluid can deliver a
positive return on investment. Some of the contributing factors include:
• Additional 20°C tolerance provided without accelerating normal
insulation system aging rate (achieved through additional loading)
• Fire mitigation equipment can be removed from service,
eliminating some maintenance expenses
• Costs incurred to remediate future spills may be reduced
• Reduced risk of dielectric failure caused by bubble formation
during overload
• Reduced risk of collateral damage to other equipment by not
incurring dielectric pool fire
• Avoid capital expenditure on costly site works, such as fire walls

Many mineral oil filled transformers are being pushed to carry load
beyond nameplate rating even though the exact condition of their
cellulose insulation is unknown. Such practices accelerate the aging of the
paper insulation, potentially reaching end of life.
Fortunately, replacing the old mineral oil (retrofilling) with natural ester
fluid is a cost-effective way to slow the thermal aging rate of insulation,
enabling increasing load-ability of transformers.
Abetterunderstanding
ofFR3forretrofill
We get a lot of questions on FR3 and natural ester fluid – especially when
it comes to retrofilling transformers. That’s why we’ve put this guide
together on the top 15 questions (and answers) – to help organisations
better understand the challenges and possibilities of retrofilling with FR3,
and assist them to make investment decisions with greater certainty.
Turn the page to see the top 15 questions on retrofilling
transformers with FR3 natural ester fluid.

#1 Fluidmiscibility
Which transformer oils are compatible
with FR3 fluid for retrofilling?
Compatible: Mineral oil, R-Temp, synthetic ester
Not-compatible: Silicone
Extensive laboratory testing and field experience has confirmed excellent
miscibility and overall retrofill compatibility for FR3 natural ester fluid
with conventional mineral oil and high temperature hydrocarbon fluids
(i.e. R-Temp fluid). FR3 fluid is not miscible with silicone and should not
be applied in transformers previously containing silicone.
While FR3 fluid is miscible and compatible with conventional transformer
mineral oil, it is important that the fluid be maintained in as pure a state
as when new, to avoid decreasing the performance and environmental
benefits.
Unlike most other fluid types, the residual transformer oil in a properly
retrofilled transformer should not reduce the fire point of Envirotemp
FR3 fluid below the NEC minimum of 300°C. Thus, mineral oil content of
up to 7% does not impact fire point (keeps fire point above 300°C).
Read more on miscibility and transformer oil compatibility in
the Envirotemp FR3 fluid datasheet
Get more detailed retrofilling guidelines for power and
distribution transformers

#2 Freebreathing
Can I only use FR3 fluid in hermetically
sealed transformers?
FR3 fluid is recommended for use in ‘non free breathing’ transformers.
Restated, FR3 fluid is not recommended when the fluid stays in
continuous contact with ambient air (for example, in transformer designs
with oil conservators without a bag). If the exposure is not continuous,
but eventual or rarely, or if the oxygen availability is limited (confined air),
the solution is acceptable. Typical transformer designs meeting the ‘non
free breathing’ classification includes:
• hermetically sealed designs with expandable
radiators/corrugated tanks
• oil conservator designed or retrofitted with a
bladder/diaphragm/air seal, and
• designs with nitrogen or air head spaces incorporating
pressure relief devices
Even in a true free breathing design, the oxidation of FR3 fluid will occur
over a long term, measured in years. The real result of extreme FR3 fluid
oxidation is an increase in viscosity. Over time, there is potential that the
viscosity of FR3 fluid will increase to an unacceptable level, impacting
heat transfer capabilities, before the anticipated life of the transformer;
hence, FR3 fluid is not recommended in true free breathing transformer.
See this article on Oxidation of transformer oils and how FR3
natural ester compares in the laboratory and in field

#3 Insulationregeneration
Will FR3 fluid heal existing problems in a
transformer?
No. FR3 fluid cannot “regenerate” insulation materials
Degradation (or ageing) of the solid cellulose insulation is irreversible.
Thermal ageing of the paper cannot be avoided – however it can be
slowed. By retrofilling with FR3 fluid, the “remaining life” of the
transformer will be extended by a reduction of ageing velocity at the
same operation temperature.
As the above image shows, FR3 fluid is proven to protect the insulation
paper 5-8 times longer than mineral oil. That extends asset life, reduces
total cost of ownership and improves grid reliability.
So how exactly can the ageing process be slowed with FR3
fluid? Find out here.

#4 Firesafetyclassifications
All materials burn, so which fire safety
tests are important?
The classification of insulating liquids pertaining to fire safety and
designation “less flammable liquids” is dependent upon fire point alone.
A “K-Class” fluid possesses a fire point
greater than 300°C. For transformers,
international standards and fluid
designations by fire laboratories and
insurance companies declare “approved
transformer fluids are those that have a
fire point greater than 300°C” (i.e. K-class
fluids). Fire point is the determining fluid
characteristic to eliminate the potential
for a transformer (pool) fire.
What does this mean for FR3?
There has never been an oil fire
reported in over 1 million
installations over the past 20 years.
Want more information on how you can improve your fire
safety? Here’s why you should retrofill with FR3.

#5 Coldweather
How does FR3 fluid perform in application
at cold temperatures?
FR3 fluid is recommended for all transformers, regardless of ambient
temperature, where the oil is not in direct contact with outside air. FR3
fluid maintains breakdown voltage equivalent to mineral oil, down to -
50°C, as shown in the graph below.
Cargill recommend using start-
up procedures similar to those
recommended for mineral oil
filled transformers (refer IEEE
C57.93 or IEEE C57.106; there
is no known equivalent in IEC –
a CIGRE Workgroup is being
formed in 2017).
For applications where devices require mechanical movement to complete
their function (i.e. switches and circuit breakers), the transformer should
be warmed to at least -10 °C, as FR3 fluid can inhibit physical movement of
the device at very high viscosities.
The behaviour and dielectric performance of FR3 in cold
temperature environments in addressed in full in this article.

#6 Moisture
Since FR3 fluid attracts moisture, how
does that impact performance?
FR3 fluid doesn’t “attract” water (moisture).
It has a higher saturation point than mineral oil, and it is more tolerant of
water than mineral oil. At room temperature, FR3 fluid can dissolve about
1000 mg/kg of water to become saturated compared to 60 mg/kg for
mineral oil.
So, what happens inside the transformer?
Water moves between the solid insulation and oil trying reach
equilibrium (relative saturation). Paper produces water as a by-product of
thermal aging, which acts as a catalyst for continued degradation.
Because mineral oil is hydrophobic, the water stays in the paper.
Since Envirotemp FR3 fluid is comparatively hydrophilic, water is
absorbed by the fluid or wicked away from the insulation paper.

Hydrolysis of natural ester
“consumes” the water and
produces fatty acids. This
process removes dissolved
water.
FR3 fluid is in essence “self-
drying”. Water concentrations
in the fluid will be reduced to
hydrolysis over time.
More here.
What does this mean for transformer life?
So, in general, an insulation system will be dryer (lower % saturation) with
natural esters. Subsequently, the solid insulation system will age more
slowly when it is dryer. Natural esters, in effect, dry out the transformer.
As a result, IEEE C57.154 and IEC
60076-14 (high temperature
insulation systems) validates the
enhanced aging capabilities of
FR3 fluid, declaring an FR3 fluid
filled transformer can run 20°C
warmer than mineral oil while
not accelerating aging.
By comparison, a wet mineral oil filled transformer loses its dielectric
strength very quickly.
Read up on FR3 fluid's high temperature capability enabling
smaller, more effective transformers with increased loading.

#7 Acidlevels
If FR3 fluid has high acid levels, how do I
process my fluid?
Mineral oil: reactive, short chain acids; can be corrosive
FR3 fluid: non-harmful, long chain acids; transesterification
Because of hydrolysis (the consumption of H20 and production of non-
reactive, long chain fatty acids) during the aging process, FR3 fluid will
possess higher acid levels than mineral oil.
However, mineral oil produces reactive, short chain acids, which can be
corrosive to the transformer interior. FR3 fluid produces non-harmful,
long-chain acids. So, “high acid levels” in FR3 fluid isn’t a concern; it
proves that the solid insulation system is aging more slowly.
Common transformer oil processing techniques
FR3 fluid can be processed using common (to mineral oil) equipment,
materials, and processes, including “reconditioning” (via degassing
equipment) and “reclaiming” (using Fuller’s Earth or Bauxite).

FR3 can strengthen the insulation paper
Furthermore, high acid levels in FR3 fluid from hydrolysis combined with
high operating temperature of a transformer has proved to be beneficial
to the solid insulation system (cellulose) through a reaction called
transesterification. While secondary to hydrolysis, it has a stabilizing
effect on insulation aging.
Combination ester attaches to weak points of the cellulose. Molecules formed by
hydrolysis attach to the cellulose, strengthening the paper.
More information on paper life, transesterification,
and grid reliability.

#8 DissolvedGasAnalysis
Can I perform DGA on FR3 fluid?
Yes. In general, the same sampling and analysis procedures can be used
with FR3 fluid as with mineral oil. Common DGA ratios can be used as well
as a FR3 fluid-specific Duval triangle.
IEEE C57.155 (published in December, 2014) is the ester dielectric fluid
dissolved gas analysis standard. There is currently no IEC equivalent
standard.
Cargill also has its own FR3 fluid DGA guide, which is based upon
thousands of FR3 fluid filled transformer samples. It addresses questions
such as:
• What should I expect when I see an FR3 fluid DGA report?
• What methods are used to interpret FR3 fluid DGA reports?
• What should I remember about DGA?
All transformer produce stray gases (gases produced during normal
operation). FR3 fluid produces different stray gases (primarily ethane)
compared to mineral oil. Stray gases produced by FR3 fluid have been
shown to be predictable and of no concern.
For more on this dissolved gas analysis with natural ester fluids
and FR3, see our dedicated FR3 DGA hub.

#9 PowerFactor
What is the Power Factor of FR3 fluid?
Power factor is the ratio of resistance current to capacitance current in an
insulation system. The power factor value depends on, among other
things, the level of insulation dryness in new transformers. For operating
transformers, changes in power factor can indicate increased levels of
moisture or other contaminates in the insulation system. There are
several variables that impact power factor measurements, even for new,
essentially dry uncontaminated units, including:
• the ratio of solid to liquid insulation
• the type of dielectric fluid
• coil design
• and temperature
Understanding FR3 Power Factor
The dielectric loss characteristics of Envirotemp FR3 fluid, a natural ester
fluid, differ from those of mineral oil. The chemical makeup of natural
esters has a slightly more polar character compared to mineral oil. This
translates into a higher dissipation factor, all other variables equal.
Distribution transformers
The power factor measurements of the distribution system models using
FR3 in conjunction with distribution production data indicate that a
typical new distribution transformer impregnated with FR3 fluid would
have a power factor measurement about 50% higher (0.75% vs. an
identical unit impregnated with mineral oil of approximately 0.50%, for
example).

Power transformers
The power factor measurements of the power transformer system
models using FR3 fluid were approximately 100% higher than the same
models using mineral oil. This higher relative value for the power
transformer models is due to the higher ratio of oil to paper in the
insulation system being measured.
Power factor increase over mineral oil of various winding-winding insulation models
using Envirotemp FR3 fluid.
These measurements, in conjunction with power OEM production data,
indicate that a typical new power transformer impregnated with FR3 fluid
would have, for example, a power factor measurement around 0.40% vs.
an identical unit impregnated with mineral oil of approximately 0.20%.
For more on transformer power factor and FR3, see the FR3
resources page.

#10 Materialscompatibility
Is FR3 fluid compatible with all
transformer materials?
In general, if a transformer component or material is compatible
with mineral oil, it is also compatible with FR3 fluid.
A thorough (but not comprehensive) compatibility study has been
performed with FR3 fluid and an array of materials/components
commonly used in transformers.
When investigating the compatibility of a new material or product, ask
the vendor if they have run compatibility tests with vegetable oil. Their
response will yield the FR3 fluid response. Transformer manufacturers
have the responsibility of verifying the compatibility of their specific
materials of construction.
Read the technical report on material compatibility in FR3
Regarding gaskets, Cargill recommend
‘good housekeeping practices’.
Specifically, by the time a transformer is identified as a retrofill candidate,
it has probably operated for several years. The condition of the gaskets
likely includes wear & tear (swelling from contact with oil), mechanically
set (it has taken a ‘set shape’, dried out, cracked, etc). If “not touched”,
the gaskets may survive without incident. However, when you retrofill, it
is likely the gaskets will be “touched”, either physically or indirectly.

If the tank and/or the gasket itself (in an aged, set, potentially cracked
condition) is moved, the outcome is likely to be less than desirable. This
has nothing to do with any interaction with FR3 fluid, but rather the
mechanical integrity of the gasket. The same recommendations would
apply to a service company flushing/reprocessing/refilling with mineral
oil. The outcome is not provoked by the new mineral oil; rather, it is
because the aged gasket was directly or indirectly moved.
Tap Changers and FR3 fluid
CTR Manufacturing have developed FR3 fluid-filled tap changers with
enhanced performance, based on the oil quenching technology which is
100 years old, and proven. Developing their new FR3 fluid-filled tap-
changers, CTR took care that they have a solution that is based on
advanced technology but is economical at the same time, which is what
their end customers require.
At the same time, they have addressed the issue of today’s great concern
about the environment and its protection, meeting the worldwide
requirement for the use of biodegradable fluids such as FR3.
Read the Case Study on CTR developing FR3 filled tap changer.
Get the technical report on material compatibility in FR3

#11 HVapplications
Can I use FR3 fluid at high voltages?
Yes, FR3 fluid can be used at voltages as high as 1800kV
Test results, reaching voltages as high as 1800kV on non-homogeneous field
distribution, yield the conclusion that FR3 fluid’s BDV and dielectric strength
is equivalent to mineral oil in all cases except for extremely divergent
geometries (needle to plane), where FR3 yields reduced BDV. This requires
further investigation, justifying the current use of safety margins.
The permittivity (dielectric constant) of FR3 fluid (3.2) differs from
mineral oil (2.2), affecting dielectric stress distribution. This value must be
understood and integrated into the dielectric design of a transformer.
Field experience with the world’s largest FR3 transformer
The world’s largest power transformer filled with natural ester FR3 fluid
has been operating at the highest voltage level in Germany’s grid for
almost three years. Read about it in this Transformer Magazine article.

#12 Interfacialtension
Is interfacial tension a meaningful
property for FR3 fluid?
Interfacial Tension (IFT) is an effective and sensitive indicator of
polar oil contaminants in mineral oil dielectric coolant, but is not
regarded to the same degree when assessing the quality of
natural esters like Envirotemp FR3 fluid.
The reason is that natural ester fluid is slightly polar on its own
and is less affected by small levels of polar contaminants.
None of the natural ester fluid standard specifications in ASTM, IEEE nor
IEC use the interfacial tension test method to place IFT limits on natural
ester fluids. The D6871 standard states that Interfacial tension
performance criteria are being assessed; therefore, requirements have
not been established.
Based on the variation inherent in the measurement, the relative polarity
of natural ester fluid causing insensitivity to polar contaminants and the
lack of appropriate standard specification limit criteria, Cargill does not
monitor IFT in its standard testing protocols. Furthermore, Cargill
recommends that the emphasis on quality of FR3 fluid should be focused
on dissipation factor at 25°C and 90/100°C instead of an inappropriate
test method in natural ester fluid standard specs.
For more on the extensive testing regime that FR3 fluid has
undergone, download the Test Summary, on our FR3 page.

#13 Reusability
What can I do with my used FR3 fluid?
Depending upon the level of degradation, FR3 fluid can be
reconditioned and reclaimed, similar to mineral oil.
Used FR3 fluid can be recycled (it’s acceptable for use as biofuel
feedstock). Used FR3 fluid is of interest to the rendering industry (e.g.
companies that pick up used restaurant grease) for recycling into oils,
lubricants, and soaps.
Similarly, to the dominant disposal method for used mineral oil, used FR3
fluid can be burned (for heat recovery). If disposing in this manner, we’d
recommend, burning a 90% mineral oil / 10% FR3 fluid mix in an industrial
boiler.
Because FR3 fluid is
biodegradable, if disposed
of in landfills, used FR3 fluid
will fully biodegrade over
time.
Read more on the biodegradability and environmental benefits
of FR3 fluid and how it compares to mineral oil.

#14 Derating
Will there will be any derating of the
transformer by changing from MO to FR3?
No.
The rationale for this position would be that due to FR3 fluid’s higher
viscosity, in a retrofill, the transformer may run a few degrees warmer
than it did with (less viscous) mineral oil.
If (for example) the transformer specification reads ’55 AWR’ and the
mineral oil filled unit was factory tested at 54 AWR, it may be the position
of the manufacturer that the transformer would exceed the temperature
rating. However, this is more than offset by FR3 fluid’s enhanced thermal
capabilities (now standardized in IEC 60076-14 and IEEE C57.154, which
declare that an FR3 fluid filled transformer can run 15°C (Kraft) to 20°C
(TUK) warmer than its MO equivalent and not accelerate aging).
Restated, by amending the transformer
specification to include one of the standards
noted above, there is no reason to de-rate
the transformer.
For more on FR3 fluid thermal
capabilities, take a look at the
updated brochure for FR3 fluid.

#15 Retrofillprocess
Are there additional steps when
retrofilling transformers with FR3?
Essentially there are four easy steps to follow to
retrofill transformers with FR3, as follows:
• Drain the oil
• Rinse tank and radiators with FR3 fluid
• Drain again and remove dregs / sludge
• Fill again using new FR3 fluid
There are two detailed guides from Cargill – for distribution transformers
and power transformers, which outline the entire process, including pre-
retrofill steps and condition assessment. These documents are further
supported by the Storage and Handling guide for appropriate fluid usage.
For more on retrofilling, see the separate guides on:
• power transformer retrofill
• distribution transformer retrofill and
• storage and handling guide

Stillgotquestions?
We hope our Top 15 Questions on Retrofilling with FR3 has been helpful
to you. If you’ve got other questions on retrofilling, or FR3 fluid generally,
we are more than happy to answer your questions.
Contact us on the details below, visit our website, or browse the FR3
brochure and datasheet, which summarise the key information on FR3.
Contact Insulect
Australia, New Zealand, Pacific.
1300 446 565 OR +61 3716 6700
sales@insulect.com
FR3 Fluid Brochure FR3 Fluid Datasheet

15-questions-retrofilling-transformers-fr3-insulect

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to 15-questions-retrofilling-transformers-fr3-insulect

Similar to 15-questions-retrofilling-transformers-fr3-insulect (20)

15-questions-retrofilling-transformers-fr3-insulect