Low-voltage equipment insulation coordination structure of the terminals from design to material selection have higher requirements, this article attempts to insulation coordination principle, low-voltage equipment insulation coordination requirements Analysis of low-voltage electrical terminals in the application and design requirements:
Insulation insulation co-ordination with the principle
Insulation co-ordination is based on product requirements and the surrounding environment to select the electrical insulating properties, and only based on the period of its life under a variety of effects (such as voltage and other factors) strength, insulation products can be achieved with the ultimate goal.
A comprehensive consideration of low-voltage equipment, work environment, affect the insulation coordination to the following factors:
And equipment related to the rated voltage; Rated insulation voltage; by the device over-voltage during operation to determine the rated impulse voltage. Other environmental conditions such as: temperature, humidity, solar radiation, heating, ventilation, dust, water vapor, etc.; other factors such as: pollution, material properties (tracking index CTI), the role of time the voltage, frequency, altitude (atmospheric pressure), electric field, uniform electric field; non-uniform electric field.
2, insulation damage and influencing factors
One of insulation breakdown (thermal runaway) is in a strong electric field, dielectric loss and dielectric internal heat because, if the heat was too late loss, the temperature rising, leading to low molecular weight volatiles escape leaving the material elements structural damage, and finally resulting in insulation breakdown;
Insulation breakdown factors:
Temperature, humidity, voltage and frequency
The other is that the insulation material insulation aging process of the device is running a variety of factors, the occurrence of irreversible physical and chemical changes, resulting in electrical materials, mechanical properties of the rapid changes in damage to insulation aging.
Such as: thermal aging, thermal insulation materials, oxygen, water, alone or in combination under the effect of low molecular weight volatiles, or the product of escape; generate free radicals in the molecular chain reaction that strand breaks; triggered automatically accelerate catalytic material damage; produce hydrolytic degradation; or produce polymer chain polymerization, resulting in performance degradation or complete destruction of material;