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What are the factors affecting insulation resistance of wires and cables?

June 10, 2021

1. Ambient temperature:
The coefficient of insulation resistance is closely related to temperature. The higher the temperature is, the smaller the insulation resistance is. This is a conclusion drawn from numerous experiments and practices. The coefficient of insulation resistance decreases exponentially with the increase of temperature, while the conductance (power conduction) power increases with the increase of temperature.

2. Humidity effect:
Conductance -- a parameter indicating the current transmission capacity of a conductor. The conductivity of water is large, and the water molecule is much smaller than that of polymer (cable sheath material). When the surrounding humidity is high, the water molecule is easy to penetrate into the insulation, resulting in the increase of conductivity and the decrease of cable insulation resistance.

3. Purity of insulating material:
Insulation refers to wrapping the charged body with non-conductive material. What if the purity of insulating material is not enough? What about the conductive materials mixed in the insulating materials—— There is no doubt that this will reduce the insulation resistance of the cable, and ultimately affect the quality of the finished cable. This is an important factor affecting the insulation resistance of cables.
Cable insulation resistance is one of the main electrical properties of insulating materials, which is an important index to measure wire and cable products. Once it is lower than a certain numerical standard, it will lead to low power transmission efficiency, waste of power, increase the probability of cable breakdown and increase the risk. Therefore, we must pay attention to this key issue when purchasing wires and cables.