Properties Standards Definitions
Viscosity ISO 3219 The viscosity of a fluid is a measure of its resistance to flow under a shear stress.
Gelation time The period of time for a thermosetting system to pass from a liquid to a non-flowing gel.
Glass transition ASTM D 3418 Approximate midpoint of the temperature range over which a material undergoes
a phase change from a hard, glass-like state to a rubbery state or vice versa.
Thermal class IEC 60085 Designation of an Electrical Insulating Material (EIM) or Electrical Insulation System (EIS)
equal to the numerical value of the maximum operative temperature in degree Celsius
for which the EIM/EIS is appropriate.
Dielectric constant ASTM D 150 The real part of the relative complex permittivity. It is also the ratio of the equivalent
parallel capacitance, Cp, of a given configuration of electrodes with a material
as a dielectric to the capacitance, Cv, of the same configuration of electrodes with vacuum
(or air for most practical purposes) as the dielectric.
Loss tangent ASTM D 150 The ratio of the loss index (k") to the relative permittivity (k') which is equal
to the tangent of its loss angle () or the cotangent of its phase angle ().
Volume resistivity ASTM D 257 The volume resistance multiplied by that ratio of specimen volume dimensions
(cross-sectional area of the specimen between the electrodes divided by the distance
between electrodes) which transforms the measured resistance to that resistance obtained
if the electrodes had formed the opposite sides of a unit cube.
Dielectric strength ASTM D 149 The voltage gradient at which dielectric failure of the insulating material occurs under
specific conditions of test.
Flexural strength DIN 53452 The maximum stress at the outer fibers at the moment of break.
Strain at break % DIN 53452 The strain at the outer fibers at the moment of break, expressed in %.
Flexural elastic modulus DIN 53457 The ratio, within the elastic limit, of stress to corresponding strain expressed
in megapascals (MPa).
Tensile strength DIN 53455 The maximum load in meganewtons divided by the minimum cross-sectional area of the
specimen in square metres.
Elongation at break % DIN 53455 The ratio, multiplied by 100, between the extension of the specimen at the moment of break
and the original gauge length.
Fire protection class IEC 60076-11
UL 94
F0= low fire risk level, particular flammability precautions not required; F1= medium/high
fire risk: the flammability level must be reduced, fire must be extinguished within a specific
time interval; C2= transformer suitable to work, transportable and storable at ambient
temperature down to -25 °C; E3= high condensation, intense pollution or both
the conditions mixed together; UL 94 HB= horizontal burning flammability test.