1 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of
E.I. DuPont de Nemours & Co. Frequent Questions & Answers
for DuPont TM ReliatraN Global Energy Solutions Version1 dated
June,2003 Slide 2 2 PERFORM WHEN THE HEATS ON NOMEX is a Registered
Trademark of E.I. DuPont de Nemours & Co. Global Energy
Solutions n Contents n What is ReliatraN page 5 ~ 6 n ReliatraN
Criteria page 7 n What is NOMEX? page 8 ~ 15 n What are the major
advantages of page 16 ReliatraN Brand Transformers ? ReliatraN
Brand Transformers ? n What are the benefits to the users of page
17 ReliatraN Brand Transformers ? ReliatraN Brand Transformers ? n
How does DuPont maintain the high quality page 18 ~ 20 and
reliability of ReliatraN transformers? and reliability of ReliatraN
transformers? n How does ReliatraN perform under moisture? page 21
~ 27 Slide 3 3 PERFORM WHEN THE HEATS ON NOMEX is a Registered
Trademark of E.I. DuPont de Nemours & Co. Global Energy
Solutions n Contents n How does ReliatraN perform under dirty
condition? page 28 ~ 29 n Whats the meaning of load loss by various
insulation class? page 30 ~ 33 n How is dielectric withstand of
ReliatraN ? page 34 ~ 35 n How well does ReliatraN perform during
overloading? page 36 ~ 37 n How well does ReliatraN withstand short
circuit ? page 38 n What is the fire behavior of ReliatraN ? page
39 ~ 45 Slide 4 4 PERFORM WHEN THE HEATS ON NOMEX is a Registered
Trademark of E.I. DuPont de Nemours & Co. Global Energy
Solutions n Contents n How is ReliatraN environmentally friendly ?
page 46 ~ 48 n What does partial discharge mean to dry type
transformer ? page 49 n What is VPI process ? page 50 ~ 51 n What
is the maximum rating of ReliatraN transformers? page 52 n Index
page 53 Slide 5 5 PERFORM WHEN THE HEATS ON NOMEX is a Registered
Trademark of E.I. DuPont de Nemours & Co. Global Energy
Solutions n ReliatraN is poised to be the chosen brand for
value-added transformer solutions that apply to various
distribution transformer applications. n What is ReliatraN ? Slide
6 6 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of
E.I. DuPont de Nemours & Co. DuPont TM ReliatraN Brand
Transformers are manufactured with UL Certified Insulation
Materials, by a global network of ISO 9001 Certified Manufacturers,
meeting the highest of International Standards for Quality, Design,
Construction and Performance DuPont TM ReliatraN is a Trademark of
E. I. DuPont de Nemours and Co. Providing Global Energy Solutions
to the Electrical Industry Slide 7 7 PERFORM WHEN THE HEATS ON
NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co.
Global Energy Solutions n DuPont TM ReliatraN Criteria n The
ReliatraN standards are continuously reviewed to incorporate new
experience, materials, test procedures, etc or to adapt new
requirements Slide 8 8 PERFORM WHEN THE HEATS ON NOMEX is a
Registered Trademark of E.I. DuPont de Nemours & Co. Global
Energy Solutions n The superior electrical properties of NOMEX
paper and pressboard provide unique capabilities for electrical
equipment, resulting in new classes and ratings. This includes: n
High Level of Safety n Increased Load Capability n Reduced Size and
Weight n Long Term Reliability n What is NOMEX ? Slide 9 9 PERFORM
WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de
Nemours & Co. Global Energy Solutions n NOMEX Electrical
Insulation has been used in the most critical applications in all
types of electrical equipment. Ventilated Dry Transformers Resin
Cast Transformers Liquid Immersed Transformers Generators AC/DC
Motors Reactors Hermetic Motors Gas Filled Transformers Slide 10 10
PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I.
DuPont de Nemours & Co. Global Energy Solutions The unique
capabilities of materials made from Nomex aramid polymer are a
result of its superior Thermal, Chemical, Mechanical and Electrical
properties The Advantages of NOMEX Slide 11 11 PERFORM WHEN THE
HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours
& Co. Global Energy Solutions n Long Term Stability up to 220C
n Short term exposures up to 350C is possible n Stable properties
over a wide range of temperature and humidity conditions n Will not
Melt, Flow or Support Combustion below 250C, with no toxic or
corrosive Off-Gases below 750C THERMAL The Advantages of NOMEX
Slide 12 12 PERFORM WHEN THE HEATS ON NOMEX is a Registered
Trademark of E.I. DuPont de Nemours & Co. Global Energy
Solutions n No weak C-H bonds creates a strong resistance to
chemical attack by acids and alkalis n Compatible with all oils,
resins, varnishes, fluorocarbons, refrigerants CHEMICAL NN C C HH
OO n The Advantages of NOMEX Slide 13 13 PERFORM WHEN THE HEATS ON
NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co.
Global Energy Solutions MECHANICAL n High tensile strength and tear
resistance prevent manufacturing problems n High abrasion and cut
resistance prevent production and operational failures n Good
compression resistance provides a stable and rigid structure during
short circuit or other mechanical stresses The Advantages of NOMEX
Slide 14 14 PERFORM WHEN THE HEATS ON NOMEX is a Registered
Trademark of E.I. DuPont de Nemours & Co. Global Energy
Solutions ELECTRICAL n The low Dielectric Constant enables better
distribution of stresses between the insulation and the cooling
medium n The low Dissipation Factor, even at high temperatures,
reduces dielectric loss n High Resistivity at high temperatures up
to 250C in use n Excellent Dielectric Strength under 50/60Hz and
under impulse conditions The Advantages of NOMEX Slide 15 15 The
Advantages of Nomex Nomex is a DuPont Registered Trademark Slide 16
16 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of
E.I. DuPont de Nemours & Co. n What are the major advantages of
DuPont TM ReliatraN Brand Transformers ? n These State-of-the-Art
ventilated dry type transformers provide the best solution in
reliable and versatile equipment Safe equipment which can be placed
close to the loadSafe equipment which can be placed close to the
load Flexibility in variable load situationsFlexibility in variable
load situations Increased overload emergency capabilityIncreased
overload emergency capability Reduced Size and Weight for better
space utilizationReduced Size and Weight for better space
utilization Economical solutions for the distribution of
powerEconomical solutions for the distribution of power ReliatraN
is a Trademark of E. I. DuPont de Nemours and Co. Slide 17 17
PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I.
DuPont de Nemours & Co. n What are the benefits to the users of
DuPont TM ReliatraN Brand Transformers ? n Highest Quality
Standards DuPont standards for design and manufacture exceed the
local and global standards to ensure high quality and reliability /
long lifeDuPont standards for design and manufacture exceed the
local and global standards to ensure high quality and reliability /
long life n Longest Warranty DuPonts network of qualified
manufacturers of ReliatraN transformers offer unprecedented five
(5) years warrantyDuPonts network of qualified manufacturers of
ReliatraN transformers offer unprecedented five (5) years warranty
n Cost Savings Lowest total owning cost from purchase to disposal
over the lifetime of the equipmentLowest total owning cost from
purchase to disposal over the lifetime of the equipment ReliatraN
is a Trademark of E. I. DuPont de Nemours and Co. Slide 18 18
PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I.
DuPont de Nemours & Co. n How does DuPont maintain the high
quality and reliability of DuPont TM ReliatraN transformers? n
DuPont provides the most updated technology on design,manufacturing
and testing to partners and continuously monitors and audits all
aspects of production to deliver quality without any failure. n
Simple processing enables OEMs to produce constant quality and
reliability. All processes are visible to detect any potential
defect of transformer. constant quality and reliability. All
processes are visible to detect any potential defect of
transformer. ReliatraN is a Trademark of E. I. DuPont de Nemours
and Co. Slide 19 19 Coil Manufacturing Process Cast coil VDT
Preheat resin Weigh resin Mix resin pouring Assemble mold curing
Disassemble mold - - Impregnation(VPI) Impregnation(VPI) drying
drying Sophisticated process/ many parameters to quality impact
Simple process/ less parameters to quality impact - - - Slide 20 20
PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I.
DuPont de Nemours & Co. n One of the special requirements for
the transformer installed at Nuclear Power Plant is longer life
installed at Nuclear Power Plant is longer life ( 40 years). ( 40
years). VDT had been used in many Nuclear Power Plants in US VDT
had been used in many Nuclear Power Plants in US due to reliable
long life due to reliable long life n Failure rate of VDT at field
is less than half of that of other dry transformers in US.
ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide
21 21 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of
E.I. DuPont de Nemours & Co. n How does DuPont TM ReliatraN
perform under moisture ? n NOMEX itself has high resistance under
high humidity. n VPI processing assure that windings are well
protected against harsh environment such as moisture and dust. n
Many tests and historical cases at operation sites have proved that
VDTs were safe to operate without outage at high humid conditions.
ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide
22 22 PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of
E.I. DuPont de Nemours & Co. n If a dry type transformer is
energized after long storage period under high humidity,it is
recommended either to wipe dirt and moisture or to energize without
loading before placing a load on transformer. n We do not recommend
starting or operating a transformer with free moisture on the coils
as there may be surface deposits that are conductive when wet.
ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide
23 23 Relative Volume Resistivity of Materials (ohm - cm) Nomex is
a DuPont Registered Trademark 10 20 10 16 10 12 10 8 10 0 10 -6 10
-10 } } } } Insulators Semiconductors Conductors Superconductors
Nomex 50C 220C { Nomex is a DuPont Registered Trademark Slide 24 24
Relative Volume Resistivity of Materials (ohm - cm) Nomex is a
DuPont Registered Trademark 10 20 10 16 10 12 10 8 10 0 10 -6 10
-10 } } } } Insulators Semiconductors Conductors Superconductors
Epoxy Resin 50C 100C 150C { Slide 25 25 Superior Humidity
Resistance * RelativeDielectric Dissipation Volume HumidityConstant
FactorResistivity (%) (60 Hz) (60 Hz)(ohm- cm)
_____________________________________________________ Dry 2.5 0.006
10 16 50 2.7 0.006 10 16 95 3.2 0.011 10 14 * Properties for
Nomex10 mil (0.25 mm) T-410 Nomex is a DuPont Registered Trademark
Slide 26 26 Moisture resistance of VDT insulated with NOMEX A
1000KVA ventilated dry type transformer with NOMEX insulation was
used in a special moisture demonstration by exciting the
transformer at full voltage immediately after being in a
thunderstorm. Nomex is a DuPont Registered Trademark Transformer
description It is 1000KVA rated 13800 volts primary and 480Y volts
secondary. The temperature rating is 150C rise at a max. ambient of
40C. The BIL rating of the high voltage is 95KV. The prior history
of the transformer includes a short circuit test and impulse test
following the short circuit test. The transformer was then
subjected to higher impulses and subsequently flashed over at 138
KV. The partial discharge inception voltage when tested as
individual coils was 1.9 times rated voltage at 400 Hertz
excitation. The Demonstration The transformer was placed outdoors
during an extremely severe thunderstorm. The thunderstorm lasted
about one hour and 1.5 inches of rain fell. Immediately there
after, the transformer was brought to the testing area and
excitation was applied. The transformer withstood its full
operating voltage with no sign of imminent flashover. Slide 27 27
Nomex is a DuPont Registered Trademark Conclusion The NOMEX
insulated ventilated dry type transformer with VPI treatment
exhibits superior moisture resistance and can be used in outdoor
locations in a properly designed outdoor enclosure. The
thunderstorm demonstration was performed to show the superior
moisture resistance of coil construction. Moisture resistance of
VDT insulated with NOMEX Case study by Southern Transformer Co.
Alexander D.Kline,President Slide 28 28 PERFORM WHEN THE HEATS ON
NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co.
n How does DuPont TM ReliatraN perform under dirty condition? n
Coil structure is well constructed to separate each disk, which
will not allow cumulative dust collection between disks. n Enough
cooling space in LV, gap between LV/HV and HV ensure effective
cooling even at harsh environment such as cement plants and mines n
One ASEAN power utility has operated several VDTs for more than 15
years without any maintenance at all, though a thick layer of dust
covered windings. ReliatraN is a Trademark of E. I. DuPont de
Nemours and Co. Slide 29 29 Slide 30 30 PERFORM WHEN THE HEATS ON
NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co.
n Whats the meaning of load loss by various insulation class? n The
higher insulation class makes it possible to build smaller size of
coils, eventually leading to smaller transformer size. n The one of
the advantages of H class dry type transformer is compactness and
lower no load loss with more load loss compared with other
transformers below H class. ReliatraN is a Trademark of E. I.
DuPont de Nemours and Co. Slide 31 31 PERFORM WHEN THE HEATS ON
NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co.
n Most of transformers operate at significantly below the full
rated load(average 60%) which benefits lower no load loss in terms
of economic view. n Therefore, higher temperature designs more
fully utilize the raw materials and optimize losses, which is the
growing trend in the West. n Reliatran can be built for specific
load loss, lower than class H transformer by request. standard
class H transformer by request. ReliatraN is a Trademark of E. I.
DuPont de Nemours and Co. Slide 32 32 0.94 Slide 33 33 PERFORM WHEN
THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de
Nemours & Co. Temp. Coil Size Comparison Class (% of Class H)
Class (% of Class H) Class B130 Class F115 Class H100 Class C 90
gher winding temperatures allow smaller coils and smaller magnetic
cores, saving cost, space and weight. n Higher winding temperatures
allow smaller coils and smaller magnetic cores, saving cost, space
and weight. Slide 34 34 PERFORM WHEN THE HEATS ON NOMEX is a
Registered Trademark of E.I. DuPont de Nemours & Co. n How is
dielectric withstand of DuPont TM ReliatraN ? n Due to lower
dielectric constant of NOMEX than other insulation materials, It
has better distribution of stresses throughout transformer n There
is no thick layer of Epoxy resin which means No cracking on coils.
One of the common problems with cast coil is cracking to cause
failure. n Disk winding structure distributes the voltage stress
evenly and efficiently to meet BIL requirement of all standards.
ReliatraN is a Trademark of E. I. DuPont de Nemours and Co. Slide
35 35 NOMEX Brand Paper & Pressboard The Dielectric Constant of
NOMEX sheet insulation is very low compared to most insulating
materials. Nomex 1.5-2.5Air 1.0 Inorganics 3.0-5.0Mineral Oil 2.2
Glass 5.0-6.0Silicone 2.7 Epoxy4.0-6.0 Cellulose 4.5 The closer to
the cooling medium(air), the better the distribution of stresses
throughout the transformer. Nomex is a DuPont Registered Trademark
Slide 36 36 PERFORM WHEN THE HEATS ON NOMEX is a Registered
Trademark of E.I. DuPont de Nemours & Co. n How well does
DuPont TM ReliatraN perform during overloading? n Based on GB
standard, the average winding rise is 125C and max. hottest
temperature is 180C. n In this case there is temperature margin
which is 40C differential between thermal capability of Nomex(220C)
and max. hottest temperature(180C). This contributes to higher
overloading capability. n For certain cases, one can put dual
ratings on the name plate for flexible operation either with lower
load loss or higher capacity. ReliatraN is a Trademark of E. I.
DuPont de Nemours and Co. Slide 37 37 PERFORM WHEN THE HEATS ON
NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co.
Steady State Loading on the Basis of test temperature riseSteady
State Loading on the Basis of test temperature rise (Quoted from
ANSI C59.96-IEEE Guide for Loading Dry type distribution and power
transformer) (Quoted from ANSI C59.96-IEEE Guide for Loading Dry
type distribution and power transformer) ReliatraN is a Trademark
of E. I. DuPont de Nemours and Co. Rated average winding
temperature rise For each degree C below the rated temperature
rise, increase rated load by 80C 115C 150C 0.57% 0.43% 0.35% If a
1000KVA is 100C average winding temperature rise, the additional
rating for over loading can be calculated. (115C - 100C) x 0.43% +
(150C - 115C) x 0.35% = 18.7% ===> 1000KVA x 1.187 = 1187KVA *
Note: In general, ReliatraN provides about 30% additional
capability for overloading based on practical design. Slide 38 38
PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I.
DuPont de Nemours & Co. n How well does DuPont TM ReliatraN
withstand short circuit ? n Design principles utilized for these
transformers minimize axial and radial mechanical forces in case of
short circuit accident. n Transformers using this design have
passed short circuit tests mechanically and thermally for more than
30 years (in the US). n VPI process with varnish enhances
mechanical strength of coils to prevent failure by short circuit
accident. n In addition, the disk structure in HV coil can hold
winding robustly. ReliatraN is a Trademark of E. I. DuPont de
Nemours and Co. Slide 39 39 PERFORM WHEN THE HEATS ON NOMEX is a
Registered Trademark of E.I. DuPont de Nemours & Co. n What is
the fire behavior of DuPont TM ReliatraN ? n Aramids do not melt
(hence it will not help the fire to spread) and generate little or
no smoke and emit no toxic gas. n Epoxy resin may emit some toxic
gases when decomposed by fire such as SO2, hydrogen sulfides and
halides [Ref.1] n Specialty tests like CENELEC HD-464 indicate that
VDT had less smoke, less weight loss, quicker self extinguishment,
less support to combustion than cast coil that VDT had less smoke,
less weight loss, quicker self extinguishment, less support to
combustion than cast coil n Nomex does not support combustion and
can only be burned with difficulty - even at elevated temperature
(LOI >> 21%) ReliatraN is a Trademark of E. I. DuPont de
Nemours and Co. Slide 40 40 Quoted from Development of Insulating
Systems in Distribution Transformers - Improvement of Fire
Resistant Characteristic by G.LE ROY and F.SANDOZ n Full size
testing of distribution transformer behavior under fire has been
possible thanks to the building by the French Coal Board Research
Center (CERCHAR) of a fire gallery guaranteeing against all
environment pollution risks nClass H VDT: only slight effects
occurred after some times - pyrolysis of the superficial varnishes
and metal frame paints ---. Let us note that this good behavior is
a consequence of the choice of materials done on this equipment, on
the basis of systematic fire test on samples(oxygen index at
various temperatures, combustion gas analysis). Class B cast coil:
Contrary to class H VDT, this equipment behavior was rather
disappointing and even, in some way, surprising. About 3 minutes
after being exposed to fire, whilest temperature reached only about
150C, the transformer went into flames. In spite of the radiating
panels being switched off, combustion self supported itself until
insulating matters complete destruction. n Conclusion: Especially
the class H VDT, the only one having shown a completely
satisfactory behavior during the full size fire test. Slide 41 41
Transformer typeVDTCast coilSiliconUgilec T Class H(Aramid)Class B
Rating(KVA): mass tank/vessel (kg): 630 400250 250 Liquid --190/40
338/60 First fire occurrence (min): Fire end (min): 303 20
407011055 Total energy measured at 12 m from the fire (MJ after
40/60 min): Energy emitted by radiating panels (MJ): Transformer
part in total energy (%): Combustible destruction part (%) Released
carbon dioxide mass(kg): Released HC1 mass(kg): Released soot And
dust mass (kg): 225/225600/640700/4900400/500 336 143 ** 336 48
PERFORM WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I.
DuPont de Nemours & Co. n There are no materials in VDT coils
causing allergy and itch to human body n The quantity of materials
requiring disposal is significantly less than with cast resin coils
(> 4 times) n Compact size with lighter weight require less
active parts,which contributes for energy saving and green
environment. (Production of silicon steel/copper wire entails
fossil fuel consumption resulting in air/water pollution.)
(Production of silicon steel/copper wire entails fossil fuel
consumption resulting in air/water pollution.) ReliatraN is a
Trademark of E. I. DuPont de Nemours and Co. Slide 49 49 PERFORM
WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de
Nemours & Co. n What does partial discharge mean to dry type
transformer ? n Reliatran has a thinner layer of varnish without
any possible air bubble inside and is designed to have low voltage
stress far below corona inception voltage. n Cast coil transformers
assume the epoxy resin fill the gaps and therefore design for epoxy
dielectric, assuming no air - if any air bubbles appear, there will
be high stress on the air and partial discharge will develop. It
may cause insulation breakdown resulting in transformer failure. if
any air bubbles appear, there will be high stress on the air and
partial discharge will develop. It may cause insulation breakdown
resulting in transformer failure. ReliatraN is a Trademark of E. I.
DuPont de Nemours and Co. Slide 50 50 PERFORM WHEN THE HEATS ON
NOMEX is a Registered Trademark of E.I. DuPont de Nemours & Co.
n What is VPI process ? n This is the most evolved technology to
produce high quality coils with advanced equipment and material. n
Impregnation is done inside tank under vacuum/pressure condition
and there are no varnish drops outside tank. ReliatraN is a
Trademark of E. I. DuPont de Nemours and Co. Slide 51 51 PERFORM
WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de
Nemours & Co. n During curing, there is some evaporation of
solventless varnish due to cross linking process between monomers
and resin. The vapor is not toxic and is exhausted out by oven
chimney. Varnish does not cause skin irritation or allergic
reaction to people. n Excess varnish can be returned to storage the
tank after impregnation process without any waste. ReliatraN is a
Trademark of E. I. DuPont de Nemours and Co. Slide 52 52 PERFORM
WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de
Nemours & Co. n What is the maximum rating of DuPont TM
ReliatraN transformers? n VDT transformers have been produced up to
15MVA and 35KV voltage class. Most popular range of product is up
to 3000KVA. In general, Power Utilities limit electricity supply to
users below 10 MVA as max. due to distribution reliability and
economic reasons. In general, Power Utilities limit electricity
supply to users below 10 MVA as max. due to distribution
reliability and economic reasons. DuPont TM ReliatraN is a
Trademark of E. I. DuPont de Nemours and Co. Slide 53 53 PERFORM
WHEN THE HEATS ON NOMEX is a Registered Trademark of E.I. DuPont de
Nemours & Co. n Index n 1.Safety Aspects of Using Aramid and
Paper and Pressboard in Dry Type Transformer Dr.J.W.Rothuizen/
Switzerand Dr.J.W.Rothuizen/ Switzerand n 2.Development of
Insulating Systems in Distribution Transformers - Improvement of
Fire Resistant Characteristics G.LE Roy/ F.Sandoz/France G.LE Roy/
F.Sandoz/France n 3. Moisture Resistance of Nomex - Insulated
Glazed Coils Alexander D.Kline/USA Alexander D.Kline/USA n 4.ANSI
C59.96 - IEEE Guide for Loading Dry Type Distribution and Power
Transformer n 5. CENELEC Norm HD 464 - Specialty test for Severe
Environments,Thermic Impulse and Fire ReliatraN is a Trademark of
E. I. DuPont de Nemours and Co. Slide 54 54 PERFORM WHEN THE HEATS
ON NOMEX is a Registered Trademark of E.I. DuPont de Nemours &
Co. Global Energy Solutions PAPER AND PRESSBOARD UL RECOGNIZED
DuPont TM ReliatraN is a Trademark of E. I. DuPont de Nemours and
Co.