When the electric field strength
of the epoxy board applied to the insulating material is higher than the
critical value, the current through the insulating material will increase
sharply, the insulating material will be broken or decomposed, and the insulation
performance will be completely lost. This phenomenon is called insulation
breakdown. The voltage at which breakdown occurs is called breakdown voltage,
and the electric field strength during breakdown is called breakdown strength.
The unit is kV/m. The breakdown of solid insulating materials can be roughly
divided into electrical breakdown, thermal breakdown, and discharge breakdown.
Kind of form. Under the action of a strong electric field, the electric
particles inside the insulating material move violently, causing collision
ionization, destroying the molecular structure, increasing the conductance, and
finally breaking down, called electric breakdown; under the action of a strong
electric field, the inside of the insulating material occurs due to dielectric
loss If the heat is too late to dissipate, it will increase the internal
temperature of the insulating material, leading to breakdown of the molecular
structure and breakdown, which is called thermal breakdown; under the action of
a strong electric field, the bubbles contained in the insulating material first
undergo collision ionization and discharge The impurity is also vaporized by
the electric field heating, and the impurity vaporizes and generates bubbles,
so the bubble discharge further develops, resulting in the breakdown of the
entire material, which is called the discharge breakdown breakdown voltage,
which is in the continuous boost test, in the specified test Under conditions,
the voltage at which the sample breaks down.
Epoxy board refers to the quotient
of the breakdown voltage and the distance between the two electrodes of the
applied voltage under the specified test conditions. The electrical strength
test result can be used to detect the change or deviation of the performance
from the normal value due to process changes, aging conditions or other
manufacturing or environmental conditions. Flashover refers to the gas or
liquid medium surrounding the sample and the electrode under electrical stress.
When the insulation performance is lost, the test circuit current caused by
this will prompt the corresponding circuit breaker to operate. The appearance
of the carbonized channel or the breakdown of the penetrating sample can be
used to distinguish whether the test is breakdown or flashover. In fact, the
breakdown of the insulation structure often occurs in multiple forms such as
electricity, heat, and discharge, and it is difficult to separate them
completely. Generally speaking, when the material has poor heat resistance,
high working temperature, and poor heat dissipation conditions, the possibility
of thermal breakdown is greater. The electrical breakdown strength of solid
insulating materials is higher than the thermal breakdown strength, while the
discharge breakdown strength depends on bubbles and impurities. Therefore, the
breakdown strength fluctuates greatly. The breakdown strength decreases as the
ambient temperature increases. In a uniform electric field, the breakdown
voltage is proportional to its thickness, that is, the breakdown strength does
not change. In practice, the electric field distribution is generally uneven.
The electric field strength at a certain point in the insulating material first
reaches a critical value and then breaks down first, causing the entire
insulation Breakdown of materials. Therefore, in actual use, the breakdown
voltage of the insulating material is not proportional to the thickness. The
methods that can be used to improve the breakdown strength of the insulating
material are: keep it clean, without harmful impurities in the material; make
the entire insulating material have a dense overall structure , Use reasonable
impregnation or other methods to eradicate pores or bubbles in the insulating
material; improve the electric field distribution to make it as uniform as
possible.
Epoxy board reasonably selects
materials and constitutes an insulating structure so that each part can
reasonably assume the role of electric field strength and prevent breakdown
caused by partial discharge; improve the environmental conditions of the
insulating material and adopt protective measures such as casting and surface
coating. In order to enhance heat dissipation, reduce vibration and protect the
main insulation structure from direct contact with moisture, ozone and other
harmful gases. The test method and standard for measuring the breakdown voltage
is GB/T1408, which specifies the test method for measuring the short-term
electrical strength of solid insulating materials (power frequency (48~62Hz)),
which is used as the surrounding medium for the test of solid insulating
materials. , But not suitable for liquid and gas tests.
Get your CNC machining projects of Epoxy Board started today
When you send out 3D CAD documents to us, JY Machinery will provide you with instant price, on-demand delivery time, as well as design for manufacturability comments for your customized CNC machining components on materials and also producing process, to make sure that the component can meet your expectations as well as budget plan demands.
Get in touch with us today for a free quote!
Skype: Chat on Skype
Email: info@jycncmachining.com
Phone: +86 15905915652