Types Of Cable Glands And Their Applications
A cable gland is a device attached to the end of an electrical cable to secure that particular part of the device. Cable glands permit its entry into the electrical equipment, enhancing the system with earthing, grounding, bonding, insulation, sealing, retention and strain relief.
They are applicable for the processing industry or where protection is needed to avoid hazards such as an explosion or high temperatures and manufactured accordingly. They are assembled mechanically in such a manner that the cable gets sealed, providing earthing to the inner armour, which increases the mechanical strength of the cable connection and avoids the loss of contact during the presence of vibration in the cable. They are also known as cable connectors, cable fittings, cord grips and cable strain reliefs.
Factors considered while choosing cable glands:
1) Where are we using it, indoors or outdoors?
2) Which type of area, explosive or hazardous or safe industrial environment?
3) Which type of surroundings are we installing, dusty or dumpy?
4) Would there be any presence of corrosive materials or gases nearby?
5) Is it suitable for the size and type of cables used?
Glands are manufactured by considering different environments like oil and natural gas. In case of any abnormalities, glands like flameproof, explosive proof. Single compression cable glands in small industries and double compression cable glands in large scale construction areas. PVC glands for the control cables in the instrumentation field. Field hose glands are used commonly in the presence of high temperatures.
There are four cable glands classified as single compression, double compression, flexible hose, PVC. There are several factors to be considered before selecting a cable gland which are:
- Type of cable
- Size of the cable gland
- Entry permit type or thread description
- Circumstance (normal or abnormal situation)
- Manufacturing material of the gland
For performing different cable management in the system, the cable glands have to perform several functions as they have to provide earthing, grounding, bonding, insulation and strain relief. They help seal the cables that pass through the bulkheads of gland plates (majorly used as a sealing device that protects the enclosures of the electrical equipment). Cable glands have different aspects and applications such as:
EARTH CONTINUITY: The ability to withstand any form of fault currents in the cable gland can be tested in the case of metallic construction and an armoured cable.
HOLDING FORCE: Only a certain amount of resistance is allowed on the cable due to the presence of the gland.
ENVIRONMENTAL PROTECTION: The area around the cable is enclosed and sealed in the outer cable sheath, such that there will not be any effect of external factors on the cable.
ADDITIONAL SEALING: A gland enables an extra level of sealing where there is a need for high ingress protection.
Generally, metal and plastic are used in the manufacturing of the gland. Metal glands have a wide range of applications, such as areas with a high demand for chemical and mechanical stability, hence used in chemical industries and technological firms. Its advantage is its durability over a long period, rigid stability and ability to last through wet conditions. The brass cable glands are resistant to corrosion and have good thermal and electrical conductivity. The brass cable glands are the traditional choice that offers strength and resistance to magnetism and deformation at high and low temperatures. One can use them for different applications such as indoor, outdoor, straightening, weatherproof, threaded, industrial.
Plastic cable glands are in applications that require saltwater resistance as plastic makes the cable gland salt water-resistant and resistant to weaker acids and grease. Brass cable glands are mostly for controlling devices, measuring devices, machinery and within medical equipment. The plastic cable glands terminate electrical cables by ensuring that they are attached and secured to the equipment where sealed. A seal maintains a connection, which keeps dust and moisture out.
Nylon cable glands are for instrumentation, data cables, electrical power and telecommunication. They are ideal for flexible cables where high strain relief is required. Nylon cable glands can come in different colours, like red and blue, which means you can colour code them. When used in certain facilities colour-coded system for your data or telecommunications application would make maintenance work a lot easier and more efficient. Hence, they help in protecting the cable from external factors such as dirt, dust, fluid and can curb any electrical spark or flame. The cable gland mountings comprise of flanged, bolted, nuts, threads, adhesive or compound. There would also be additional features depending on the environment. Such as fire and explosion-proof, shielding from EMI and RFI to reduce electromagnetic or radio frequency interface. Hence, they must be installed properly to ensure appropriate ingress protection and other mechanical and electrical properties requirements. All cable glands have a rating system that ensures that the buyer understands the product.
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