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Types Of Insulators In Overhead Transmission

Transmission line insulators separate, contain, and suspend transmission line conductors. They protect short circuit paths between the earth and the transmission line. There are several types of insulators in overhead transmission lines. The most known are the pin type, suspension type, strain insulator, shackle insulator, and stay insulator.

Types of electrical insulators in transmission lines:

1. Pin-type insulators:

The name “pin” came from its constructional design. Pin-type insulators are used for the transmission of lower voltages. The transmission range of pin type is up to 33 kV (kilovolts). Pin-type insulators are secured with steel or lead bolts onto transmission poles. These are typically used for straight-running transmission lines. There is a groove on the upper end of the insulator for housing the conductor. The conductor passes through this groove and is bound by the annealed wire of the same material as the conductor. We can use this type of insulator beyond 33kv, but that becomes bulky in size & costly.

2. Suspension-type insulators :

Suspension-type insulators are used to transmit above 33kv. Above 33kv using of pin type is uneconomical. In a suspension-type insulator, many insulators are connected in series to form a string, and the conductor is suspended at the bottom end of this string. In contrast, the other end of the string is secured to the cross-arm of the tower. Each insulator of a suspension string is called a disc.

Advantages of Suspension-Type insulators :

(i)Suspension-type insulators are very economical voltages beyond 33 kV.
(ii) Each unit or disc of the suspension-type insulator is designed for low voltage, usually 11 kV. As per the operating voltage requirement, we can add a number of discs in series.
(iii) If any one disc is damaged, the whole string does not become useless because the damaged disc can be replaced by a sound one.
(iv) The suspension arrangement provides greater flexibility to the line. The connection at the cross arm is such that the insulator string is free to swing in any direction and can take up the position where mechanical stresses are minimum.
(v) The suspension-type insulators are generally used with steel towers. As the conductors run below the tower’s earthed cross-arm, this arrangement provides partial protection from lightning.

3. Strain-Type insulators:

Strain-type insulators are horizontally suspended suspension insulators. When there is a dead end or a sharp corner in the transmission line, the line has to sustain a great tensile load of conductor or strain. The discs of strain insulators are used in the vertical plane. When the tension in lines is exceedingly high, two or more strings are used in parallel at long river spans. Voltage rating is almost equal to suspension type.

4. Shackle-Type Insulators:

Shackle-type insulators, similar to strain-type insulators, are used on sharp curves, end poles, and section poles. These insulators are single and round porcelain parts mounted horizontally or vertically. The shackle insulator or spool insulator is usually used in low-voltage distribution systems. They can be directly fixed to the pole with a bolt or cross arm.

5. Stay-insulators :

The insulator used in the stay wire is called the stay insulator and is usually of porcelain and is designed so that in case of breakage of the insulator, the guy-wire will not fall to the ground.

This Is Complete Information On Types of Electrical Insulators, Insulators In Overhead Transmission Lines.
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How Do You Know That The Mice And Rats Are Gone?

Rodents and mice poison bait does little to solve a rodent problem and, in most cases, makes the problem worse. Poison bait by design is food for the rats. Putting out poison attracts rats.

Rodents spread diseases on their own and carry fleas and ticks that spread even more diseases. Rats can also carry mites, whose populations can grow significantly enough that they feed on residents. Their populations grow rapidly, and they can chew up gas lines and even disrupt your home’s foundation. Rodent issues should always be taken care of by a professional.

Rodents are some of the most resilient creatures on the planet. Unless you remove all of the pests in a short span of time and eliminate all of their possible access points, the chance you will end up with another infestation is high. Knowledge about rodent life cycles and habits is crucial for an effective removal plan. Rodent Control San Antonio

Do-it-yourself methods for homeowners rarely work for long, and poisons should not be handled without training in safe, effective use. Cornered rats will attack humans, and groups of rats can attack pets. It is always best to leave rodent removal to the professionals. Buildings are different, and each type of rodent must be treated in a different way. During your initial consultation, your pest control specialist will take the time to assess your problem, try to identify the kind of rodent you are dealing with, and possibly offer some short-term solutions like sealing foods in thick containers and trimming branches that overhang your home.

You can expect your Rodent control specialist to create a customized plan to eliminate your rodent problem and help keep your home rodent-free. A variety of tactics may be combined into a strong action plan. The simplest, less expensive, and less invasive options are often used first, but with large infestations, aggressive treatment may be necessary. Rodents, mice, and rats are problematic inside of any structure. While rodent issues will generally be more pervasive in areas where construction may be older and sanitation may not be ideal, rodents can infest any building. Recognition of a mouse or rat problem is not necessarily a reflection on one’s tidiness or cleanliness; it is unfortunately a byproduct of living and requires expertise and care to manage.

Rats of either species, especially young rats, can squeeze beneath a door with only a 1/2-inch gap. If the door is made of wood, the rat might gnaw to enlarge the gap, but this might not be necessary.

Norway Rats
Norway rats eat a wide variety of foods but mostly prefer cereal grains, meats, fish, nuts, and some fruits. When searching for food and water, Norway rats usually travel an area of about 100 to 150 feet in diameter; seldom do they travel any further than 300 feet from their burrows or nests. The average female Norway rat has 4 to 6 litters per year and can successfully wean 20 or more offspring annually.

Roof Rats
Like Norway rats, roof rats eat a wide variety of foods, but they prefer fruits, nuts, berries, slugs, and snails. Roof rats are especially fond of avocados and citrus, and they often eat fruit that is still on the tree. When feeding on a mature orange, they make a small hole through which they completely remove the contents of the fruit, leaving only the hollowed-out rind hanging on the tree. They’ll often eat the rind of a lemon, leaving the flesh of the sour fruit still hanging. Their favorite habitats are attics, trees, and overgrown shrubbery or vines. Residential or industrial areas with mature landscaping provide good habitat as does riparian vegetation of riverbanks and streams. Roof rats prefer to nest in locations off the ground and rarely dig burrows for living quarters if off-the-ground sites exist.

Roof rats routinely travel up to 300 feet for food. They can live in the landscaping of one residence and feed at another. They often can be seen at night running along overhead utility lines or fence tops. They have an excellent sense of balance and use their long tails to steady themselves while traveling along overhead utility lines. They move faster than Norway rats and are very agile climbers, which enables them to quickly escape predators. They can live in trees or in attics and climb down to a food source. The average number of litters a female roof rat has per year depends on many factors, but generally, it is 3 to 5 with 5 to 8 young in each litter.

Rats eat and contaminate foodstuffs and animal feed. They also damage containers and packaging materials in which foods and feed are stored. Both rat species cause problems by gnawing on electrical wires and wooden structures such as doors, ledges, corners, and wall material, and they tear up insulation in walls and ceilings for nesting.

Norway rats can undermine building foundations and slabs with their burrowing activities and can gnaw on all types of materials, including soft metals such as copper and lead, as well as plastic and wood. If roof rats are living in the attic of a residence, they can cause considerable damage with their gnawing and nest-building activities. They also damage garden crops and ornamental plantings.

Among the diseases, rats can transmit to humans or livestock are murine typhus, leptospirosis, salmonellosis (food poisoning), and rat-bite fever. Plague is a disease that both roof and Norway rats can carry.

Rats, like house mice, are active mostly at night. They have poor eyesight, but they make up for this with their keen senses of hearing, smell, taste, and touch. Rats constantly explore and learn, memorizing the locations of pathways, obstacles, food and water, shelter, and features of their environment. They quickly detect and tend to avoid new objects and novel foods. Thus, they often avoid traps and baits for several days or more following their initial placement. While both species exhibit this avoidance of new objects, this neophobia is usually more pronounced in roof rats than in Norway rats.

Both Norway and roof rats can gain entry to structures by gnawing, climbing, jumping, or swimming through sewers and entering through toilets or broken drains. While Norway rats are more powerful swimmers, roof rats are more agile and are better climbers.

Norway and roof rats don’t get along. The Norway rat is the larger and the more dominant species; it will kill a roof rat in a fight. When the two species occupy the same building, Norway rats may dominate the basement and ground floors, with roof rats occupying the attic or second and third floors. Contrary to some conceptions, the two species can’t interbreed. Both species can share some of the same food resources but don’t feed side by side. Rats can grab food and carry it off to feed elsewhere.

Rats of either species, especially young rats, can squeeze beneath a door with only a 1/2-inch gap. If the door is made of wood, the rat might gnaw to enlarge the gap, but this might not be necessary.

Inspect your yard and home thoroughly. If the answer to any of the following questions is yes, you may have a rat problem.
Is there evidence rodents are feeding on fruit/nuts that are in or falling from the trees in your yard?
Do you see burrows among plants or damaged vegetables when working in the garden?
Do you see rats traveling along utility lines or on the tops of fences at dusk or soon after?
Have you found rat nests behind boxes or in drawers in the garage?
Are there smudge marks caused by the rats rubbing their fur against beams, rafters, pipes, and walls?
Do you see burrows beneath your compost pile or beneath the garbage can?
Are there rat or mouse droppings in your recycle bins?
Have you ever had to remove a drowned rat from your swimming pool or hot tub?
Do you see evidence of something digging under your garden tool shed or doghouse?
Do you find rat droppings around dog or cat dishes or pet food storage containers?
Do you hear noises coming from the attic just after dusk?
Have you found remnants of rat nests when dismantling your firewood stack?
Does your dog or cat bring home dead rat carcasses?

Rodent contamination can happen in any area of your home or building. Almost every home has had a rodent infestation at one point.