What are the insulation requirements for manual tools in electrical operation environments?

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Introduction

In electrical operations, different operation environments have specific requirements for the insulation performance of manual tools. The following will elaborate in detail on the specific requirements for the insulation performance of manual tools in different electrical operation environments from multiple aspects.

I. High-voltage Environment

In a high-voltage environment, such as in industrial and mining enterprises engaged in power production, manual tools need to have extremely high insulation performance. An insulation resistance tester (commonly known as a megohmmeter) is mainly used to measure and verify the insulation resistance of electrical equipment such as motors, transmission lines, and cables, so as to determine whether their insulation performance can meet the needs of the equipment. In such a high-voltage environment, the insulation performance of manual tools is required to withstand the impact of high voltage and prevent leakage or short-circuit accidents.

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II. Medium-voltage Environment

For the medium-voltage environment, take medium-voltage SiC devices as an example. They can enable the power electronic converter to be directly connected (without a 50/60Hz transformer) to the medium-voltage power grid and adopt a simple topology. In this case, the insulation design of the filter inductor of the directly connected medium-voltage converter faces more challenges. In the design, the insulation requirements of the power grid need to be considered, including short-term power frequency overvoltage and lightning impulse voltage, etc. To meet these requirements, factors such as interlayer insulation, insulation between the winding and the iron core/ground, air gap discharge between the winding and the iron core, and the local electric field need to be considered.

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III. Air-insulated Switchgear Environment

In the air-insulated switchgear environment, since the altitude, air humidity, and pollution level of the operation area are not the same, these factors will all affect the insulation performance of the switchgear. The altitude affects the air density, which in turn affects its insulation strength; air humidity and pollution have a greater impact on the insulation performance of the surface of solid insulating parts. Therefore, manual tools used in this environment need to consider these factors and have good insulation performance to adapt to different environmental conditions.

IV. Live Working Environment

Distribution Network Live Working Environment
In the new type of distribution network live working, it is necessary to detect the insulation resistance. In order to correctly judge the insulation performance of electrical equipment and insulating tools and ensure the safety of live working, it is necessary to develop and analyze the insulation resistance detection tools.
Ultrasonic Detection Environment of Insulating Tools
During the long-term service of live working insulating tools, tiny defects may occur inside, which will affect the performance of the tools. Using ultrasonic detection technology can effectively diagnose the internal defects of materials and ensure the safety of operators. For the ultrasonic detection of solid insulating rods, two narrow-pulse-width probes with one transmitting and one receiving, plus a double-crystal arc-shaped wedge block, can be used for detection. The time and amplitude of the defect echo reflect the relative position of the defect; for the ultrasonic detection of insulating hollows, a narrow-pulse broadband probe plus a single-crystal arc-shaped wedge block is used for detection, and the defect echo is located between the outer wall and inner wall echoes.

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V. High-voltage Electrical Equipment Environment of EMUs

The high-voltage electrical equipment on the roof of an EMU not only endures the erosion of various harsh and extreme environments but also withstands the impact of various overvoltages, and the insulation performance of the high-voltage electrical equipment box is seriously threatened. In this environment, the insulation performance of the high-voltage equipment box can be improved by adding an insulation sheath of a certain length to the electrical equipment.

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Conclusion
The requirements for the insulation performance of manual tools vary in different electrical operation environments. In environments such as high-voltage, medium-voltage, air-insulated switchgear, live working, and high-voltage electrical equipment of EMUs, manual tools need to have corresponding insulation performance according to the specific environmental characteristics and requirements to ensure the safety of workers and the normal operation of electrical equipment.