The electrical insulators are important to use in the overhead transmission lines since they act as a barrier to heat flow even in households. The insulators allow easy repair and maintenance since one insulator can be fixed or repaired while the other still remain intact. This is mainly for the porcelain insulators which allow them to have a longer operational life. The insulators are mainly water, oil, wood or paper while the electrical insulators are made from other materials such as porcelain, glass and polymer. The features of these materials are further discussed below.
The type of materials used to make the insulator is important to identify before buying them as they help to know whether the selected type of insulator will fit the type of work it is intended for and the different weather conditions in the area. The most common materials that are used to make the insulators are glass, porcelain and polymers which are further discussed below.
This is the most preferred material for insulators used in the overhead transmission lines. It is made from a combination of materials like clay, aluminum silicate, quartz and feldspar. It is then concealed with a smooth glaze that provides protection from dust, moisture and other impurities. It does not have any level of porosity which helps it to preserve its dielectric strength.
It does not have any cracks or bubbles and this helps it to keep its insulation resistance high. It is flexible enough to be hooked on any shape or design which makes it the popular type of insulator material. It has the ability to survive under any conditions which increases its versatility. This means that the insulator cannot be affected even on the drastic high temperatures.
This type of material has high resistance to electricity and has low factor for thermal expansion. It has higher dielectric strength compared to the porcelain due to its hardening process which is used for manufacturing them. It is also important as the insulating properties of glass cannot be affected by the external temperatures. This is because the tensile strength of the glass material prevents it from heating up in case of high temperatures.
Another advantage of the glass material is that glass has longer service life than porcelain. Glass insulators are cheaper than the porcelain and the polymer insulators.
This insulator is also known as composite insulator which is used in the overhead lines. It consists of an epoxy resin, fiberglass and a rod-shape core which is properly enclosed with sheds of the polymer. The rod is connected with galvanized steel on both ends to help it resist the electrical heat as well as the environmental heat. They are also lightweight and can be transported without breaking or getting damaged. They also have high tensile strength which makes them the best insulators for areas with high level of environmental pollution.
The main disadvantage of the polymer insulators is that they tend to experience current leakage which happens when moisture finds its way into the insulator.
Other factors to consider when checking the materials for insulators include:
Other than the basic benefit of not allowing the electric current to pass through them, electrical insulator materials have many more benefits.
The electrical insulators can be used on different series of applications and are divided depending on the volume of the current into low voltage insulators, medium voltage insulators and high volume insulators.
Pin type insulators are used for supporting the low voltage power lines. They can be used on the conductors and also on the cables with low voltage. They have shells which are arranged in equivalent before being mounted on the pole or tower. The design is made in such a way that the inner parts are always dry to prevent electrical leakage. The conductor is bound on the top of the insulator and then it is supported by a galvanized pin. A thimble is used to avoid straight contact between porcelain and pin.
Advantages of pin insulator
Disadvantages of pin insulator
They can only be used for voltages below 50KV and if used for the higher voltages they become bulky.
Suspension insulators are used for the high voltages and supporting high voltage conductors. They have porcelain discs which are organized in a series to form a string-like structure. The conductor is adjourned at the lower end while the other end is attached to the pole or tower. The porcelain insulators used on the arrangement will depend on the working voltage.
Advantages of suspension type insulator
Disadvantages of suspension type insulator
The only disadvantage is that large spacing between the conductors is required as compared to the other types of insulators.
Post insulators that are fixed on the electrical pole for the transmission lines. They are however divided according to the usage and the position it is installed on the pole which include tie top line post insulator, horizontal and vertical line post insulators, under arm line post insulator and clamp top line post insulators.
Stay insulator is mostly used in high and medium voltage lines for rural and railway. It also called a guy insulator or an egg insulator.
Shackle insulator is also known as a spool insulator and is usually used for the low voltage power lines. It has a hole which ensures that the load is equally distributed to all directions and it can be connected both horizontally and vertically.
Strain insulators are also known as tension insulators and dead end insulators. They are used when the conductor is subjected to high tension over particular sections. They are mostly used in high voltage power systems.
The electrical insulator types are identified depending on their usage and volume of voltage it can handle. They can therefore be low voltage insulators, medium voltage insulators and high voltage insulators. The various types of electrical insulators therefore include the pin insulator, suspension insulator, stay insulator, shackle insulator, post insulator and strain insulator.
Insulators can however be classified into two forms. That is solid insulators and liquid insulators.
Solid insulators — glass or ceramics and dielectrics are made from materials with solid constructions. The materials are present in the form of thin layers on which the conducting layer sits. This creates an obstacle that allows the current to flow in a solitary direction only. The different types of solid insulator materials include: glass or ceramics, plastics and copper.
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Liquid insulators — these are the insulators that are known for their ability to hold the electrical charge indefinitely. They are mainly used for making capacitors whose basic working code lies in the temporary storing of electricity so as to make the flow smooth. The common types of liquid insulators include: mercury liquid metal, silicone and natural esters.
When planning to purchase the transmission line insulators, there are factors and features to consider. Some factors include the mechanical strength, tensile strength, porosity and the resistance to impurities. The manufacturer and producers of the insulators should also be considered as the different manufacturers may produce different features from the others. The durability of the insulators is dependent on its features. The features of electrical insulators are as discussed below.
High voltage resistance — this means that the insulators should be able to resist high voltages in order to prevent damage to the conductors. This also makes them applicable to all the electrical power systems.
Lightweight — the insulators should carry minimum weight despite being made from quality material. This makes sure they are easy to handle and transport and also reduce overhead load.
Custom design — some manufacturers take the designs from the customers and manufacture them according to their needs instead of the standard designs.
High impact resistance — the insulators should be able to resist the physical impact which makes them ideal for all kinds of environments. They should also be resistant to shock and vibration.
Strong and durable — the insulators should be built to be steady and last long which makes them attract less repair and maintenance.
Air permeability — the insulators should allow a unified flow of air through them which is essential for managing heat on high power transmission lines.
There are other factors to consider when planning a purchase which include:
Pneumatic power systems include any type of mechanised or automated processes or machinery in which motion is driven by pressurised gas or compressed air. The obvious counter-reference here would be hydraulic systems, in which motion is driven by liquids held under similar compression forces within a sealed system.
‘Pneumatic’ specifically denotes the delivery of power through controlled movement of pressurised gases (including air). In any pneumatic-powered system, the pressurised gases that drive the required mechanisms are typically delivered to where they are needed through an airtight network of rigid pipes, robust hoses, or lengths of flexible tubing.
The vast majority of these conduits are connected to each other - as well as to the various devices being powered - by a wide variety of pneumatic fittings, couplings, valves and adaptors. As a general description, a pneumatic fitting can be any type of connector designed to link components or devices in a sealed and pressurised dry-air system.
These systems and fittings are widely used today in all manner of industries and applications, ranging from construction, assembly and production line setups to a huge variety of industrial machinery, handheld tools and workbench equipment. In many workplace environments, the power that a pneumatic system delivers can often prove more versatile, reliable, cost-effective and safer than an equivalent setup powered by various electric motors and actuators.
When shopping for connectors and adaptors for this type of system, you will be presented with numerous options covering a wide variety of different assembly methods and styles. Some of the most common include:
This type is designed with speed and ease of assembly/disassembly in mind, but they are also built to provide a secure and reliable join. They typically enable entirely tool-free connection and disconnection between various tubes, pipes and tools; ideal for fittings that will frequently need to be reassembled.
The most common type of push-in fitting features a collet or ‘grab ring’ around the connection point, through which the hose or pipe slides and which then automatically grips and holds the tubing in place. Pushing down on the collet with two fingers (or a quick-release tool) instantly disconnects the fitting from the tubing.
Push-in fittings can be made from plastic or various metals. Plastics are typically used for lower pressure systems whereas metal fittings may be required in higher-temperature applications or environments.
Tube-to-tube adaptors are available in a variety of diameters, sizes, and materials. They are used to connect two lengths of tubing together, either straight or at an angle, and different types can be chosen to work with a range of materials such as nylon, polyurethane or polyamide conduit.
This type of fitting includes screw-down threading on either the inner (female) or outer (male) edge of the connector, which will be gauged to mate with matching threads on the end of a length of hose or conduit.
Fittings sold with straight threading are intended to form a solid connection between parts, but not necessarily to form an air-tight seal on their own - this threading type will require additional sealant coating or a layer of Teflon tape for use in pneumatic applications. Fittings sold with tapered threading are intended to be airtight without the need for additional coatings or tape. This may be necessary for certain working environments where sealants and coatings may lead to corrosion or contamination.
This is typically a type of push-on fitting in which the hose or tube is pushed over a barbed end for initial grip, and then a knurled nut is tightened down around the pipe and barb to provide full security of the connection for use under air pressure.
Fittings can be attached to a fairly wide range of conduit and device types - including hoses, tubing and pipe - at various points around air-powered systems. The best pneumatic fitting for your intended application and working environment will largely be dependent on the operating pressures you need the system to be running at.
However, when choosing a specific fitting type, it’s also important to be mindful of the exact sort of conduit that you are pushing the compressed air through on either side of the fitting in question. Different materials will tend to have varying properties of their own, which will often dictate the best choice of fitting to use.
A hose is typically understood to refer to a flexible type of conduit, constructed from multiple layers of robust rubberised or plastic material. It is often designed to be replaced at fairly regular intervals due to general wear and tear. For this reason, fittings designed for use with air hose may be less permanent or more easily detached, with a view to being disassembled relatively often.
A pipe in this context usually denotes a conduit constructed from more solid materials, often in a single layer or length, and generally seen as a better option for more permanent installations or runs. Pneumatic pipe fittings may well be more firmly fixed in place than other types and are sometimes specifically designed for less frequent disassembly or detachment. Pipe is commonly graded or sized for fittings according to its inner diameter.
Tubing in pneumatic systems is often something of a halfway house between hose and pipe; a relatively rigid option but with some degree of flexibility and aimed at less permanent setups than most conduit pipe assemblies. Pneumatic tube is usually sized or gauged for fittings according to its outer diameter.
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