The function and usage of insulating sleeves.
Release time:
2024-12-29
Insulating sleeves are products used to maintain the insulation of high-voltage circuits when they pass through the walls and floors of power plants and substations, through the bodies of high-voltage switchgear, or through the housings of transformers and circuit breakers.
Insulation sleeves are products used to maintain the insulation of circuits against grounded objects when they pass through the walls and floors of power plants, through high-voltage switchgear cabinets, or through the shells of transformers and circuit breakers. With the continuous development of manufacturing processes and technology levels in China's high-voltage switch industry, indoor high-voltage complete switchgear has gradually developed towards miniaturization, full insulation, and full enclosure. The dimensions and footprint of switchgear have also been reduced, and the application of insulation sleeves in switch cabinets has become increasingly common, leading to an increase in various discharge phenomena.
Functions of insulation sleeves:
Using insulation sleeves in wires, components, or cable ties can serve the following purposes:
1. Increase electrical insulation performance.
2. Increase the mechanical strength of wires or components.
3. Protect wires that are not heat-resistant.
4. Color coding for easy inspection and maintenance.
5. As a tying material, bundle multiple wires together as a whole, making it aesthetically pleasing, reducing space occupation, and enhancing product stability.
Commonly used sleeves include PVC sleeves, wax sleeves, silicone wax fiberglass sleeves, and heat shrink sleeves.
Methods of using insulation sleeves:
1. Method of adding sleeves to component leads. The leads of components are generally bare wires, which can easily cause short circuits. Adding sleeves prevents short circuits and facilitates color marking.
2. Method of adding sleeves to components. For small components, an insulation sleeve can be used to cover both the component and its leads, which can provide good insulation for components with metal surfaces.
3. Method of adding insulation sleeves to terminals. When adding insulation sleeves to terminals for insulation purposes, a sleeve can be added to every other terminal. If the purpose is to increase mechanical strength, insulation sleeves can be added to all terminals.
4. Method of adding sleeves to wires. To enhance the insulation performance of wires, a longer sleeve can be used to cover the wire. If the purpose is just to bundle the wires together, a shorter sleeve can be used.
Insulation sleeves are tested according to the Ministry of Public Security standard: GA305-2001, with the following content:
1. Compression test: Load 750N for 1 minute, deformation <25%, unload for 1 minute, deformation <10%.
2. Bending test: At room temperature and low temperature (negative 15 degrees), bend to 90 degrees using a bending machine, with no cracks.
3. Flame retardant test: Use a blowtorch to burn continuously three times, each time for 25 seconds, with a 5-second interval, self-extinguishing within 30 seconds after leaving the flame.
4. Heat resistance test: At 60 degrees Celsius, apply a force of 20N with a 5mm diameter steel ball on the wall of the insulation sleeve, with an indentation diameter <2mm.
5. Impact test: At low temperature of -25 degrees, after 2 hours, a 2kg weight dropped from a height of 100mm onto the pipe material, with no cracks.
6. Appearance introduction: The surface of the insulation sleeve is smooth, the wall thickness is uniform, and the outer diameter is measured with a small outer diameter gauge, while the inner diameter is measured with a small inner diameter gauge to ensure compliance.
7. Bending flat test: Fix the insulation sleeve on a steel frame and bend it 90 degrees, then place it in an oven at 60±2 degrees Celsius for 24 hours, and it should pass through the small inner diameter gauge under its own weight.
8. Insulation strength: Place the insulation sleeve sample in water at 20±5 degrees Celsius, after 24 hours, apply AC 50HZ, 2000V voltage for 15 minutes without breakdown. Insulation resistance >100 megaohms (with DC 500 voltage).
In thermocouple circuits, if the two thermocouples are poorly insulated or short-circuited, it will cause a shunting phenomenon in the thermoelectric potential, leading to measurement errors or even making measurement impossible. Therefore, it is necessary to use insulating materials to isolate the two thermocouples. There are many types of insulating materials, generally divided into organic and inorganic categories, with insulation sleeves made into circular or oval cross-sections available in single-hole, double-hole, and four-hole forms. Ceramic and alumina insulation sleeves are commonly used in coal quality testing laboratories.
The role of protective insulation sleeves is to prevent direct contact between the thermocouple and the measured medium, avoiding or reducing the erosion of poor media, impacts from flames and airflow, radiation, and mechanical damage to improve temperature measurement accuracy and extend the service life of the thermocouple. In addition, protective PVC insulation sleeves also serve to fix and support the thermocouple. Protective sleeves should have good airtightness (i.e., low porosity), sufficient mechanical strength, and good physical and chemical stability. Common materials for protective sleeves used in coal quality testing laboratories include high-temperature steel, quartz, and alumina.
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The function and usage of insulating sleeves.
Insulating sleeves are products used to maintain the insulation of high-voltage circuits when they pass through the walls and floors of power plants and substations, through the bodies of high-voltage switchgear, or through the housings of transformers and circuit breakers.
2024-12-29