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Electrical insulation for electric/hybrid electric vehicles
In the exciting new field of alternatively fueled vehicles, only DuPont has the necessary combination of design expertise, evaluation technology and superior electrical insulation material—DuPont™ Nomex®—to help meet original equipment manufacturers’ (OEMs’) needs.
Exceptional thermal stabilityDuPont™ Nomex® has an Underwriters Laboratories (UL) thermal rating
of 220°C and a long history of proven endurance under high thermal
stress. This high-temperature durability helps to allow miniaturization
and/or higher power density of electrical drive motors and enables
long-term electrical dependability.
This also helps OEMs to reduce the size and weight of components
such as traction motors, which in turn can increase fuel efficiency.
The effects of long-term exposure to high temperature on important
electrical and mechanical properties of DuPont™ Nomex® are shown
in Figures 1 and 2.
Superior mechanical strengthThe superior mechanical strength and resilience of DuPont™ Nomex®
insulation (refer to Table I) help extend the service life of rotating
equipment, such as traction motors, which are subjected to harsh
operating conditions that include severe shock and vibration, as well
as abrasion caused by thermal expansion and centrifugal forces.
An added benefit of the superior mechanical strength of
DuPont™ Nomex® is the manufacturing efficiencies that can
be gained from automatic insertion of slot liners.
DuPont™ Nomex® has a long history as an electrical insulation material of choice for traction motors, automotive motors and automotive generators due to its proven performance and reliability. Based on its track record of helping OEMs around the world to improve performance and prevent premature failures in these applications, OEMs are now choosing DuPont™ Nomex® to help them meet the increased power density requirements and harsh operating conditions of motors and generators used in (H)EVs.
100 140 180 220 300 340 380 100 140 180 220 300 340 380
Temperature, ˚C Temperature, ˚C
Figure 2. Effect of prolonged exposure to high temperature on the initial strength of DuPont™ Nomex®. (Tested per UL-746)
Figure 1. Effect of prolonged exposure to high temperature on the dielectric strength of DuPont™ Nomex®. (ASTM D-1830, curved electrodes)
106
105
104
103
102
106
105
104
103
102
Agi
ng ti
me,
hou
rs to
12
kV/m
m (3
00 V
/mil)
diel
ectr
ic s
tren
gth
Agi
ng ti
me,
hou
rs to
50%
of i
nitia
l st
reng
th in
mac
hine
dir
ectio
n
Log time =8262
˚C + 273– 11,44 Log time =
7461
˚C + 273– 10,40
Excellent dielectric strengthDuPont™ Nomex® features excellent electrical properties and endures electrical stresses that are
commonly encountered in (H)EVs due to the use of inverters. As shown in Table II, DuPont™ Nomex®
has excellent dielectric strength. It is important to note that these values differ from long-term
strength potential. DuPont recommends that continuous stresses in transformers not exceed
1.6 kV/mm (40 V/mil) in order to minimize the risk of partial discharges (corona). DuPont has
materials designed for applications where corona is present, should this be necessary.
Excellent chemical stabilityDecades of experience in similar types of automotive motors and generators have proven that
DuPont™ Nomex® is compatible with a wide range of chemicals, including virtually all classes
of electrical varnishes and adhesives, as well as the oils and automatic transmission fluids often
used in (H)EVs.
Design and testing expertiseAs a leader in electrical insulation systems for more than 40 years, DuPont has earned a strong
reputation for evaluating the performance of insulation used in equipment. Our experts are drawing
on this experience to help global OEMs translate their performance needs into measurable criteria,
even designing new test protocols and testing equipment when necessary.
DuPont experts in motor design are also working with top OEMs around the world to help them
develop specific solutions that will optimize their motor designs and help advance this evolving industry.
Table I. Typical mechanical properties of DuPont™ Nomex®
Nominal thickness mil (mm)
2(0.05)
3(0.08)
5(0.13)
7(0.18)
10(0.25)
12(0.30)
15(0.38)
20(0.51)
24(0.61)
25.5(0.65)
29(0.73)
30(0.76)
Test method
Tensile strength, N/cm MD XD
3918
6532
13766
219111
285152
378196
459252
606354
741497
758524
860630
841595
ASTM D-828
Elongation, % MD XD
96
118
1512
1814
1915
2217
1914
2016
1814
1916
1612
1713
ASTM D-828
Elmendorf Tear, N MD XD
0.81.6
1.22.3
3.45.2
3.97.4
6.010.8
7.414.2
9.517.2
14.223.7
N/AN/A
N/AN/A
N/AN/A
N/AN/A
TAPPI-414
Initial Tear Strength,1 N MD XD
116
168
3317
5027
7142
9355
11674
163113
201157
209159
252199
251200
ASTM D-1004
MD = machine direction of paper XD = cross direction of paper 1Data presented for Initial Tear Strength is listed in the direction of the sample per ASTM D-1004. The tear is 90 degrees to sample direction; hence, for papers with a higher reported MD ITR, the paper will be tougher to tear in the cross direction.
Table II. Typical Electrical Properties of DuPont™ Nomex®
Nominal thickness mil (mm)
2(0.05)
3(0.08)
5(0.13)
7(0.18)
10(0.25)
12(0.30)
15(0.38)
20(0.51)
24(0.61)
25.5(0.65)
29(0.73)
30(0.76)
Dielectric strength, AC rapid rise1
V/mil kV/mm
43017
55022
68027
84033
81532
82032
83033
81032
80031
73029
75030
68027
Dielectric constant2 at 60 Hz 1.6 1.6 2.4 2.7 2.7 2.9 3.2 3.4 3.7 N/A 3.7 3.7
Dissipation factor2 at 60 Hz (x10-3) 4 5 6 6 6 7 7 7 7 N/A 7 7
1ASTM D-149 using 50 mm (2 in.) electrodes, rapid rise; corresponds with IEC 60243-1 sub-clause 9.1, except for electrode set-up of 50 mm (2 in.). These rapid rise values represent 10 to 20 seconds of withstand strength.
2ASTM D-150
Product safety information is available upon requestThis information corresponds to our current knowledge on the subject. It is offered solely to provide possible suggestions for your own experimentations. It is not intended, however, to substitute for any testing you may need to conduct to determine for yourself the suitability of our products for your particular purposes. This information may be subject to revision as new knowledge and experience become available. Since we cannot anticipate all variations in actual end-use conditions, DUPONT MAKES NO WARRANTIES AND ASSUMES NO LIABILITY IN CONNECTION WITH ANY USE OF THIS INFORMATION. Nothing in this publication is to be considered as a license to operate under or a recommendation to infringe any trademark or patent right.
Please note: The properties in this sell sheet are typical or average values and should not be used as specification limits. Unless otherwise noted, all properties were measured in air under “standard” conditions (in equilibrium at 23°C, 50% relative humidity). Note that, like other products of papermaking technology, DuPont™ Nomex® papers have somewhat different properties in the papermaking machine direction (MD) compared to the cross direction (XD). In some applications (for example, motor slot liners), it is necessary to orient the paper in the optimum direction to obtain its maximum potential performance.
Copyright © 2011 DuPont. The DuPont Oval Logo, DuPont™, The miracles of science™, and Nomex® are trademarks or registered trademarks of E.I. du Pont de Nemours and Company or its affiliates. All rights reserved. K-24364 4/11
To learn more about how DuPont™ Nomex® electrical insulation can help you improve the performance and reliability of motors and generators for (H)EVs, call 1.800.931.3456 or visit www.nomex.dupont.com