1. Insulation resistance and resistivity
Resistance is the reciprocal of
conductance, and resistivity is the resistance per unit volume. The less
conductive the material, the greater its resistance, and the two are in a
reciprocal relationship. For insulating materials, it is always desirable to
have the highest resistivity as possible.
2. Relative permittivity and dielectric
loss tangent
There are two uses of insulating materials:
mutual insulation of various parts of the electrical network and the medium of
capacitors (energy storage). The former requires a small relative permittivity,
the latter requires a large relative permittivity, and both require a small
dielectric loss tangent, especially for insulating materials used under high frequency
and high voltage, in order to make the dielectric loss small, both require the
use of Insulating material with a small dielectric loss tangent.
3. Breakdown voltage and electric strength
Under a certain strong electric field, the
insulating material breaks down and loses its insulating properties and becomes
a conductive state, which is called breakdown. The voltage at breakdown is
called breakdown voltage (dielectric strength). Electric strength is the
quotient of the voltage when breakdown occurs under specified conditions and
the distance between the two electrodes that bear the applied voltage, that is,
the breakdown voltage per unit thickness. For insulating materials, the higher
the breakdown voltage and electrical strength, the better.
4. Tensile strength
It is the maximum tensile stress that the
sample bears in the tensile test. It is the most widely used and representative
test for the mechanical properties of insulating materials.
5. Combustion resistance
Refers to the ability of insulating
materials to resist burning when in contact with flames or to prevent continued
burning when they leave the flames. With the ever-expanding application of
insulating materials, the requirements for their combustion resistance become
more important. People use various means to improve and enhance the combustion
resistance of insulating materials. The higher the combustion resistance, the
better the safety.
6. Arc resistance
Under the specified test conditions, the
ability of the insulating material to withstand the arc action along its
surface. In the test, AC high voltage and small current are used, and the
arcing effect generated by the high voltage between the two electrodes is used
to determine the arc resistance of the insulating material by the time required
to form a conductive layer on the surface of the insulating material. The
larger the time value, the better the arc resistance.
7. Sealing degree
It is better to seal and isolate oil and
water quality.
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