Detection method of power cable insulation performance

Release time: 2024-09-26

In the power system, power cable is a key component of energy transmission, and its insulation performance is directly related to the safe and stable operation of the power system. Therefore, it is particularly important to test the insulation performance of power cables regularly. This paper will start with several main power cable insulation performance testing methods, combined with specific data and comparison, to explore the principle, application and importance of these methods.

Insulation resistance test

Insulation resistance test is the basic method of power cable insulation performance test. This test measures the resistance value between the cable core and the metal shielding layer or armor layer to preliminarily determine whether the cable insulation is affected with moisture, aging or defects. Generally speaking, for common power cables, the insulation resistance value should reach500~1000Mega-ohms. Below100Mega-ohms indicate that the insulation has failed and the cable needs to be replaced in time.

Data description:Suppose a paragraph0.6/1kVThe cable is used in the insulation resistance test.1000VThe resistance value obtained from the voltage measurement is800Mega-ohm, the result is within the normal range, indicating that the cable insulation is in good condition. If the test results of the same cable at different time points are determined800Mega-ohms down50Mega-ohms, it is obvious that the insulation performance is degraded and needs further inspection and treatment.

Withstand voltage test

Withstand voltage test is the key means to test the insulation strength of cable. By applying a voltage higher than its rated working voltage to the cable under certain conditions, it is observed whether the breakdown occurs, so as to judge whether the cable insulation is qualified. This test can find serious defects in the insulation and evaluate the reliability of the cable in a high-voltage environment.

Comparative analysis:Compared with the insulation resistance test, the withstand voltage test can more directly reflect the actual performance of the cable under high voltage. For example, a certain10kVIn the withstand voltage test, the cable successfully withstood25kVContinued1Minutes of voltage without breakdown, indicating that its insulation strength is higher; and another section of the same specification cable under the same conditions breakdown, indicating that there is a serious problem with its insulation.

Partial discharge measurement

For high-voltage extruded cables, partial discharge measurement is an important means to evaluate their insulation status. The measurement of partial discharge can be achieved by electrical, acoustic or optical measurement, with electrical measurement being the most commonly used. This method can capture the instantaneous charge exchange generated by the discharge, so as to find small defects in the insulation.

Data comparison:Suppose two segments of the same specificationXLPECable In partial discharge measurement, the number of discharge pulses in one section of the cable is much lower than that of the other. This indicates that the insulation state of the former is better, and the latter may have local defects and need further treatment.

Aging and stability test

The aging and stability test evaluates the stability of the insulation performance by simulating the stress environment (such as mechanical stress, electrical stress, and thermal stress) of the cable in long-term use. Thermal aging test is an important part of the process, and the service life of the cable is evaluated by measuring the performance changes before and after aging.

Data description:a certainXLPECables have experienced1000hours,150After the thermal aging test, the insulation resistance value decreased only.5%It shows that its insulation performance is stable and can meet the long-term use requirements.

There are various methods for testing the insulation performance of power cables, and each method has its unique advantages and scope of application. Through the comprehensive use of these detection methods, the insulation state of the cable can be evaluated comprehensively and accurately, and potential problems can be found and dealt with in time to ensure the safe and stable operation of the power system. At the same time, with the continuous progress of technology, new detection methods are also emerging, which provides more choices and possibilities for the insulation performance detection of power cables.

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