Insulation is the characteristic of using non-conductive materials to isolate or wrap the charged body to preventget an electric shockA safety measure of.
Good insulation can ensure the safe operation of electrical equipment and lines.
Chinese name
Insulation
Foreign name
insulativity
Definition
Insulate or wrap the charged body with non-conductive material
Role
Ensure safe operation of electrical equipment and lines
Under the action of strong electricity, the insulation material may be broken down and lose its insulation performance.After the gas insulation material and liquid insulation material are broken down, once the external factors (strong electric field) are removed, the electrical insulation performance can be restored automatically;However, the electrical insulation properties of solid insulating materials will be irreversibly lost after breakdown.Therefore, the insulation selection of electrical lines and equipment must match with the voltage level, and must adapt to the use environment and operating conditions to ensure the safety of insulation.
In addition, due to corrosive gas, steam, moisture, conductive dust, mechanical damage and other reasons, the insulation performance of insulating materials may be reduced or even damaged.Moreover, the long-term effect of environmental factors such as sunlight, wind and rain can also make insulation materials aging and gradually lose their insulation performance.
In general, the insulation resistance of newly installed or overhauled low-voltage lines and equipment shall not be less than 05MΩ；The insulation resistance of low-voltage lines and equipment in operation shall not be less than 1000 Ω/V;The insulation resistance of equipment lines in wet places should not be less than 500 Ω/V, the insulation resistance of control lines should generally not be less than 1M Ω, and the insulation resistance of high-voltage lines and equipment should generally not be less than 1000M Ω.
There are many products on the market that can improve the insulation performance of products, such as silicone flame retardant and heat conductiveSilicone rubber insulating coating，Anti pollution flashover coating，Heat shrinkable sleeveCold shrink sleeves, insulating sheaths and other products can effectively guarantee the insulation performance of products in actual operation.
test method
Announce
edit
The potential method is more suitable for judging the insulation performance of insulated joints with cathodic protection measures.The measurement method is: first, complete the connection of the line according to the requirements of the potential method measurement wiring.Second, keepCopper sulfate reference electrodeThe position of does not change, useDigital multimeterMeasure the pipe ground potential Va at the non protective end a of the insulated joint and the pipe ground potential Vb at the protective end b.When the insulation joint is in good condition, the potential difference between two sides is between 200 and 500 mV.Third, the data analysis shows that if the voltage at point b is significantly more negative than that at point a, the insulation performance of the insulated joint is considered good.If the measured voltage between two points is close, the insulation performance of the insulated joint is considered suspicious.If the auxiliary anode is far enough away from the insulation joint, it can also be judged that the pipeline connected to the non protective end is not close to or cross with the pipeline at the protective end. It can also be judged that the insulation performance of the insulation joint is very poor, or there may be serious leakage charge short circuit phenomenon, and further measurement should be made.
PCM leakage rate measurement method is mainly suitable for PCM to measure the leakage rate of insulated joints in normal use and judge the insulation performance of the insulated joints there.The measurement method is as follows: First, connect the lines at all places according to the wiring requirements of this method.Second, disconnect the cathodic protection power supply and jumper cable at the protection end.Thirdly, according to the operation steps of PCM, use PCM transmitter to input current I into the pipeline at the protective end close to the insulation joint.Fourth, use PCM outside the current input point of the protection terminalReceiver measurementAnd record the side pipe current I1.Fifth, measure and record the pipeline current I2 at the non protected end with the PCM receiver.Sixth, data processing: calculate the percentage of leakage of insulated joints in the following way.The percentage of leakage of insulated joint is equal to the current in the pipe at the non protected end of insulated joint measured by the receiver divided by the sum of the current in the pipe at the protective end of insulated joint and the protective end of insulated joint measured by the receiver multiplied by 100%.
