Waterproof cable glands, as the name implies, can be applied to the environment with water to provide safe and reliable connectors. For example: LED street lights, lighthouses, cruise ships, industrial equipment, sprinklers and so on, need to use waterproof cable glands.
At present, there are many brands and types of waterproof cable glands on the market, but in the true sense, waterproof cable glands with excellent sealing performance and safe and reliable quality are still relatively few in the market.
At present, the main evaluation standard for waterproof performance of waterproof cable glands is based on the standard of IP waterproof grade. Waterproof performance of waterproof cable gland depends mainly on the two digits XX behind IPXX, the first X is from 0 to 6, the highest grade is 6; the second digit is from 0 to 8, the highest grade is 8; therefore, the highest waterproof grade of waterproof cable gland is IP68.
Waterproof cable gland can be divided into internal thread connection, external thread connection, clamping connection and other connection according to different installation methods. Waterproof cable glands usually have waterproof and industrial plugs. Waterproof cable gland, with good special material quality, self-locking function, strong tension resistance, water-proof, dust and other characteristics, will not cause damage to the motor, and in the use process does not need to disintegrate the fixed head, the cable can be directly through, time-saving and convenient, generally used for mechanical control boxes, distribution boxes, electrical cables and other cable fixing. Waterproof cable glands are divided into seven grades in solid protection and nine grades in water protection. The standard of solid protection is divided into 0 to 67 grades. Grade 0 means no protection. Grade 1 can protect solids above 50mm from intruding into the joint, Grade 2 is solids above 12.5mm, Grade 3 is solids above 2.5mm, Grade 4 is solids larger than 1.0mm, Grade 5 is solids of protecting dust, Grade 6 is to achieve sealed state and complete protection.
2. Use method of waterproof cable gland
1. Choose suitable connector material according to the type and specification of cable connector. Nowadays, the quality of cable connector material is uneven. But in order to ensure the quality of cable connector, it is suggested that we should not be greedy and cheap, and we should choose the material of cable connector manufacturer with reliable quality.
2. It's better not to choose rainy days when cable joints are used, because water intake of cable will seriously affect the service life of cable, and even lead to short-circuit accidents.
3. Before making cable waterproof cable gland, we must read the manufacturer's product instructions carefully. This is especially important for 10 kV and above cables. Before doing this, we should think about all the procedures before doing it.
The terminal connector of single-core armored cables above 4 and 10 kV should be grounded with only one end of the steel strip.
5. Copper tube can not be pressed too hard, as long as it is pressed into position, the copper end face after pressing will inevitably have many bumps, which must be smoothed with a file, and no burrs can be left.
6. When using the blowtorch, the heat shrinkable cable joint should pay attention to the movement of the blowtorch, not to the continuous blowtorch in only one direction.
7. Dimensions of cold-shrinkable cable joints must be made in strict accordance with the drawings, especially when the support in the reserved tube is withdrawn, more care should be taken.
3. Characteristics of waterproof cable glands
Among many kinds of joints, I think you will not be unfamiliar with waterproof cable glands and rod joints. They are widely used in our daily life and work. They can be seen on the surface of many pipe fittings and products. Because of the difference of structure design and material, they have different uses. Comparing the two, the characteristics are very remarkable. But even so, it can not hide the shortcomings of the product itself, for any product, is not perfect, there are shortcomings. So, what are the shortcomings of these? Let's get to know them together.
In recent years, optical fiber connectors, USB2.0 high-speed connectors, wired broadband connectors and micro-spacing connectors are increasingly used in various portable/wireless electronic devices, and even higher-speed USB3.0 has appeared in the market. Therefore, the market application hotspots of waterproof cable glands are also changing.
For example, the process of global enterprises and market electronization is getting faster and faster, while the Chinese government invests heavily in the fields of three networks integration, smart grid, automobile and rail transit in the context of financial crisis. It can be seen that the market demands higher and higher speed interconnection and current resistance of connectors; from the perspective of consumer electronics, the application of network television is hot, and they involve a lot of things. In the application of antenna, TV system manufacturers need to set antenna in a very small space. Therefore, miniaturization and energy-saving of connectors are the important trends in the development of household appliances industry. The complex functions of body control and remote communication in automotive electronic systems also challenge the miniaturization, intellectualization, environmental protection and high reliability of connectors.
The role of waterproof cable glands in various industries is becoming more and more obvious, small size, big role, fully reflects the role of waterproof cable glands in the modern market.
In all-wrapped cable and cable joints, the function of all-wrapped insulation is not only to supplement the insulation of each conductive core to the inner protective layer, but also to tighten each core so that the cable joints will not disperse, thus reducing the manufacturing difficulties. Because the cores are fan-shaped and circular, the whole cable structure is compact, space utilization is high, outer diameter is small, material saving and manufacturing cost is reduced accordingly. This kind of cable joint has the longest use history and excellent operation record. It is still widely used up to now. The disadvantages of all-encapsulated cable are as follows:
(1) Due to the existence of gas in the gap formed by the thermal expansion and cold contraction of insulating oil in the filler around the cable core, the cable joints are free under the action of electric field, and the cable insulation is gradually damaged.
(2) Because of the existence of electric field component along the tangent direction of the insulating paper surface, dendritic carbonization cracks occur in the paper layer. At the same time, the electric field also acts on the waterproof cable gland on the filler material with much lower dielectric strength than the pure edge of the paper, resulting in the cable waterproof cable gland.
(3) In the triangular zone consisting of three cores (commonly known as the trident), the maximum temperature rise is due to the difficulty of heat dissipation, accelerating insulation aging and limiting the carrying capacity.
(4) Because there is no grounding shield outside the cores and three cores of cable joints share one grounding sheath, it is easy to transform single-phase grounding fault into inter-phase fault, thus increasing the accident probability of sudden trip and power outage.
(5) Because the viscosity of the cable collapsing agent is low and easy to flow at the working temperature, when the cable is laid under the condition of drop, the high end of the cable line will dry up due to the loss of the impregnating agent, the insulation level will decrease seriously, and the pressure inside the cable sheath will increase or the oil leakage at the low end of the cable head will occur.
