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The bending radius of the cable and its influence on the cable

1. What is the bending radius of the cable?

Cables must be actively or passively subjected to bending during the manufacturing, transportation, and installation and construction processes. When the cable is bent, the degree of bending is directly related to the bending radius of the cable.

1. The bending radius of the cable: Normally, we regard the bent cable as an arc, and the radius of the circle where the arc is located is the bending radius of the cable in the bending state.

2. The minimum bending radius of the cable: Due to the cable material and structural characteristics, the cable has a certain limit to withstand bending. The cable bending radius under this limit is the minimum bending radius of the cable.

2. The influence of too small cable bending radius on the cable

1. The effect of bending on the conductor
The cable conductor is made up of multiple single-core wires twisted at a certain pitch. The number of single wires and the pitch of the conductor determine the stability of the conductor during bending. Excessive bending will cause the conductor to become loose and loose. The protrusion directly affects the performance of the semi-conductive layer and insulating layer of the outer conductor.

2. The influence of cable bending on insulation
When the cable is bent with a certain bending radius, the insulation at the bend will undergo tensile deformation. When the bending exceeds the allowable minimum bending radius, it may cause insulation damage.

3. The effect of bending on metal shielding
Usually medium voltage cables are shielded by copper tape. When the cable is bent too much, the metal tape will wrinkle or curl, which will easily lead to insulation 
Due to the frequent occurrence of electrical fires, people have put forward higher requirements for the safety of wires and cables. Flame-retardant cables refer to cables that can spread the flame within a certain range and have the function of self-extinguishing when an electrical fire occurs.

The combustion of the cable is caused by the external heating to produce flammable gas. To realize the flame retardant of the cable, the three elements that cause the combustion must be suppressed: flammable gas, heat and oxygen. The traditional method is to add halogen-containing halides and metal oxides to the sheath material. This limits the spread of fire to a certain extent. However, because these materials contain halide, they release a large amount of smoke and hydrogen halide gas when burned. The visibility during fire is low, which brings great impact to the safety of personnel evacuation and fire fighting. obstacle. In recent years, with the continuous improvement of the level of science and technology, the flame retardant problem has been further developed from the halogen flame retardant in the past to the low halogen, halogen-free flame retardant.

2. Flame retardant grade
The determination of flame-retardant cable grade usually adopts the vertical burning test method of bundled wires and cables. The test divides wires and cables into flame-retardant A, B, and C three categories. That is to say, multiple wires or cables with a length of 3.5m (the total number is different due to the flame retardant category and the non-metallic materials contained in each meter of the wire and cable) are installed in bundles on the sample ladder and placed vertically in the test box In the medium, a gas burner with an intensity of 20.6kW is used to supply fire to the wires and cables vertically.
Class A and B flame-retardant wires and cables provide fire time for 40 minutes; Class C fire time for 20 minutes. After the test, if the carbonization height of the wire and cable does not exceed 2.5m, it will be passed. Specific grades of non-metallic materials per meter of wire and cable are as follows: A type 7 liters/meter; B type 3.5 liters/meter; C type 1.5 liters/
1. What is a special cable? What is the difference with ordinary cables?

Special cables are cables that have special uses and can be used on specific occasions. Special cables are a series of products with unique properties and special structures. Compared with ordinary wires and cables with a large quantity and a wide range, special cables have the characteristics of higher technical content, stricter use conditions, smaller batches, and higher added value. Special cables often adopt new structures, new materials, new design calculation methods and new production processes.

Second, the characteristics and classification of special cables

Special cables have special functions due to their special use occasions or specific use conditions, such as high temperature or severe cold resistance, strong acid and alkali resistance, termite resistance, low noise, superconducting, waterproof, soft and wear-resistant, and environmental protection. . So far, special cables are mainly divided into four categories: high temperature resistant wire and cable, special structure and specific purpose wire and cable, functionalized wire and cable, and new green and environmentally friendly wire and cable.

Third, the diversified development direction of special cables

The development direction of special cables is diversified. The military industry has a large demand for light-weight and high-temperature-resistant cables. In terms of construction, fire-resistant and high-temperature resistant wires and cables and low-smoke, halogen-free and environmentally friendly wires and cables can effectively prevent fire and safety accidents. In fields such as medicine and national defense that require small signal measurement, low-inductance and low-noise wires and cables are needed. For oil platforms, deep well survey cables, heating and temperature control cables, and submarine integrated cables are needed. In urban power distribution, substations, power plants and other occasions that need to transmit large currents over short distances, superconducting cables are required. In terms of industrial intelligence, super-flexible, wear-resistant and easy to move drag chain cables are needed. In the application of locomotives and AC motors, frequency conversion cables are
The installation and construction of outdoor power cables is relatively difficult due to the complex terrain and numerous equipment and facilities in the urban area. In order to avoid problems such as cable abrasion, equipment damage, and personnel safety caused by construction, the following summarizes the 6 major techniques for laying outdoor power cables.

1. Before laying the cable, check whether the type and specification of the cable meet the design requirements: armored cables should be used for direct burial laying; unarmored cables should be used in cable trays, in cable shafts, overhead and pipe laying; Flame-retardant cables should be used in public places with higher fire protection requirements.

2. Check whether the cable reel and its protective layer are intact, and whether the two ends of the cable are damp.

3. According to the actual situation of the construction site, it is determined that the cable shall be laid in direct buried, vertical shaft, pipe-through or overhead laying methods.

4. When the power cable is buried directly underground, the distance from the ground should not be less than 0.7 meters, the distance between the pipeline and other parallel pipelines should be kept at least 2 meters, and the pipeline spacing should be more than 0.5 meters during cross laying.

5. The sequence of cable laying and the location of cable brackets should be planned as a whole before construction.

Pay attention to the abrasion of the cable at the bend during construction, and ensure that the cable has enough space for expansion and 
1. Short circuit: the phenomenon that the live wire and the live wire, and the live wire and the neutral wire are short-circuited on the electrical circuit. A short circuit can easily make the metal conductor instantaneously high temperature and cause the cable insulation material to catch fire.
2. Overload operation: Due to long-term overload operation, the operating temperature of the cable far exceeds the maximum allowable temperature during normal heating, which makes the insulation material of the cable aging and dry, so it is easy to break down and cause the wire to catch fire.
3. Excessive contact resistance: The contact resistance is too large due to poor contact at the junction of line and line, line and switch, and line and other electrical equipment. When strong current passes, it will also cause local heating and high temperature and cause line fire.
4. Leakage: The quality problems of the wire, such as poor insulation performance or friction or scratches in the laying of the wire, will cause the wire to leak. The electric spark and high temperature caused by the leakage will cause the wire to catch fire.

Prevention of wire fire:

1. Short-circuit prevention: Use safe fuse electrical switches and select flame-retardant cables with high safety factors. When a short-circuit fault occurs on the electrical circuit, the fuse will blow and cut off the current, and the flame-retardant cable has its own self-extinguishing performance, which greatly reduces the spread of fire.
2. Overload prevention: Do not pull wires randomly. When using high-power electrical appliances, consider the acceptable range of wires and cables. for
To prevent aging and breakdown of insulating materials during overload operation, it is recommended to use wires and cables with better aging resistance and lower eccentricity.
3. Prevention of excessive contact resistance: The electrical wiring must be installed in strict accordance with the electrical installation regulations. If necessary, please ask a professional electrician.
Set up the line.
4. Leakage prevention: choose wires and cables with good insulation material quality and strong bending resistance. In addition, regular
Check electrical wiring and equipment,
1.Standard value: The insulation thickness specified in the wire and cable product standard is based on the applicable voltage level of the product, the size of the conductor cross-section, the size of the current carrying capacity, the environmental conditions used, the electrical properties of the insulation material, the physical and mechanical properties, and the long-term consideration Many factors of the service life are determined through scientific calculations and long-term practical experience.

The significance of the measurement: if the measured value is smaller than the specified value, the wire and cable product will lose electrical insulation until it is broken down, causing personal and property damage; if it is greater than the specified value to a certain extent (exceeding the maximum value of the wire) Path), which brings a lot of troubles to users, until they can not be used, and increases costs for production
In the production and manufacturing process of cables, the two concepts of isolation sleeve and inner lining are often encountered. The so-called isolating sheath is the sheath between the coating layers of two different metal materials, which is commonly referred to as the inner sheath. The inner lining is the core and filler (if any) of the multi-core cable. The non-metallic cladding layer on the outside and under the protective layer.
Isolation sleeve: The focus is on the word isolation. The isolation is between two different metals, such as the three-core YJV22 structure. There is a layer of PVC between the copper strip and the steel strip. At this time, the PVC plays the role of isolation. From chemical and physical From the perspective of consideration, the activities of copper and iron are different, and when they are in contact with each other, they will accelerate the oxidation of copper. Therefore, the isolation sleeve must be squeezed and cannot be wrapped, because there are gaps in the wrapping, which may cause mutual contact.
Lining layer: copper wire shielding, copper tape armoring, single-core power cable-this structure also has PVC between the shielding layer and the armoring layer, but since the two metals are of the same kind, they will not accelerate oxidation, so PVC does not need to be used. To the isolation effect, so in this case it is not called an isolation sleeve, but an inner liner. In addition, the inner liner may be wrapped.
Cushion: Generally, the word "wrap tape" is added in front of the cushion. This is used in many standards to describe its function. When the cable is armored, it is used together with the inner lining to strengthen the inner lining. The role of.
The inner lining can be squeezed or wrapped, while the isolation sleeve can only be squeezed. For cables with specifications above 10mm2, wrapping can save material costs. When the metal layer under the armor is different from the armor material, a layer of isolation sleeve must be squeezed to separate it. At this time, the isolation sleeve can replace the inner lining. Since the cores of medium voltage power cables are shielded by copper tape, and the cores of low voltage cables are unshielded, this is why we usually see why medium voltage armored cables have to squeeze the inner lining (isolation sleeve), while low voltage armored cables The reason to wrap the inner 
Flexographic printing uses a flexible relief plate to print onto a substrate, which may be a wood-pulp based, synthetic, or laminated material. When carrying out flexo printing and flat bed die-cutting inline, the printing process is directly followed by flat bed die-cutting of the sheet. The technology is predominantly found in the manufacture of packaging made from corrugated and micro-flute board, including uncoated, semi-coated, and coated substrates. Other applications of the process include the manufacture of in-store displays.Get more news about Flexographic Flat Printer,you can vist our website!

Flexo printing and flat bed die-cutting inline is particularly useful where complex die-cutting is required and/or high quality graphics combined with high productivity is needed, although the process is also often used for much less difficult work.

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Having a secure and safe connection between mated connectors is crucial to avoid potentially hazardous situations that put equipment and, most importantly, lives at risk. This is where coupling mechanisms come into play. Each coupling style has a different set of key features and benefits, but all ensure a secure connection in whatever the application might be. Since there are so many available styles, choosing the correct coupling mechanism for your application is critical to avoid problems.Get more news about Bayonet Lock Coupling,you can vist our website!

Threaded, bayonet, and push-pull are the three basic coupler styles commonly used for circular connectors. When selecting which coupler style to use, various factors must be taken into account, including technical requirements, environmental conditions (e.g., vibration, shock, moisture, dust), ergonomics, and the required number of mating cycles. User experience regarding installation and maintenance, as well as cost, must also be considered.

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In addition to being an economical option, there are also advanced coupling design features available for military D38999 connectors. This type of threaded connector features both triple-start threads and a ratcheting coupling to ensure a secure connection, even in high vibration applications. Threaded circular connectors are commonly found in communication equipment, heavy machinery, military aircraft, and missiles.

Bayonet couplers are extremely easy to install, offering both speed and convenience through their simple “push and twist” mating motion that makes them well adapted for applications where frequent mating and unmating is required. Coupling/decoupling is achieved through a ⅓ turn of the coupling ring, and mating is gained through the use of bayonet pins and ramps instead of threads.

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on the coupling ring that can provide further visual proof that the bayonet pins are in their locked position.

Circular bayonet connectors are ideal for blind mating applications and are often found in rugged industrial environments that often include shock and vibration.
As industrial connectors, they are commonly used with power generators, sensors, and engines.
Push-pull circular connectors are designed to prevent accidental disconnections through a self-latching mechanism that involves pushing a plug into a matching socket. The connection achieved cannot be broken by merely pulling the connectors apart, but rather the connector body must be
squeezed while pulling outward to break the electrical connection successfully. Unlike more traditional connectors that require a rotational force to achieve mating and unmating, push-pull connectors rely on an axial force.
Push-pull connectors can provide significant space savings because the connection/disconnection procedure requires that a technician use only two fingers. This, in turn, allows multiple connectors to be mounted close to one another.

Circular connectors with push-pull coupling are very well suited to applications where reliability is critical and fast connect/disconnect is possible. Such applications include medical, instrumentation, soldier wearables, communications, and military vehicles.
The Banana plug test probes are used with multimeters, power supplies, and other electrical gear. This economic set is perfect for replacing worn out or lost test leads. These Multimeter Test Leads can also be a great back up to bring with you in case of on-site emergencies. The test leads work with basic multimeters with standard input jacks. Color coded for proper testing, these test leads provide proper safe testing for multimeters.Get more news about banana test probes,you can vist our website!

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