Friday, April 27, 2018

How to repair charger

PDA chargers can be a somewhat fragile telephone need. They are comprised of an AC connector that is associated with a thin wire and an arrangement of adaptable prongs that embed into the charger port of your telephone. You may have a pet that can without much of a stretch bite through that wire or perhaps you stuck the charger into your telephone's port the wrong way. The wire can be frayed or broken totally or the prongs on the finish of the charger could without much of a stretch twist. Instead of spend the cash to get another charger, it bodes well to repair it at home.

Bowed Prongs 

Step 1 

View the prongs through an amplifying glass on the finish of the charger that is most distant from the AC connector divider plug, to precisely survey which are harmed.

Step 2 

Get the finish of a bowed prong with a couple of tweezers. Force the prong tenderly to a straight position. Rehash this for each bowed prong.

Step 3 

Test the straightness of the pins by tenderly squeezing the charger into the charger port of the telephone. The prongs of the charger should effortlessly coast into the mobile phone. Protection implies the prongs require all the more rectifying.

Broken or Frayed Wire 

Step 4 

Cut the rope with a couple of scissors if the rope is just frayed. Cut the battered edge off each side of the cut or if the wire was already broken. Each side of the cut or break ought to be free of stray wires and frayed protection.

Step 5 

Strip around an inch of protection from the two sides of the cut. This will uncover the wires.

Step 6 

Turn together the wires from each side of the cut. Match the shades of the wires on one side to the relating wires on the opposite side of the cut. Wire hues may differ contingent upon your telephone.

Step 7 

Wrap the uncovered wires snuggly with electrical tape.

Sensorless Vector control; Sensorless Vector control Vs V/f control

Variable frequency drive Sensorless Control

The variable recurrence drive designs of the sensorless control contain the accompanying extra capacities, which supplement the conduct as indicated by the parameterized V/f trademark.

Slip compensation

The heap subordinate distinction between the reference speed and the genuine speed of the 3-stage engine is alluded to as the slip. This reliance can be remunerated by the present estimation in the yield periods of the variable recurrence drive.

The enactment of Operation Mode for the slip remuneration empowers as speed control without input. The stator recurrence and speed are revised relying upon the VFD stack.

The variable recurrence drive slip pay is enacted amid the guided appointing. The Stator Resistance is required to guarantee a right capacity and is estimated amid the guided authorizing.

On the off chance that no guided dispatching is executed, the slip pay can be enacted physically. In these cases, enter the VFD esteem for the Stator Resistance physically as indicated by the engine information sheet.

The variable recurrence drive control conduct of the slip pay must be streamlined through the parameters on account of particular applications. The VFD parameter Amplification decides the rectification of the speed and the impact of the slip pay relatively to the difference in stack. Parameter Max. Slip Ramp characterizes the most extreme recurrence change every second keeping in mind the end goal to stay away from an over-burden on account of a heap change.

The VFD parameter Frequency Lower Limit decides the recurrence as from which the slip remuneration winds up dynamic.

Current limit value controller
Through a heap subordinate speed control, as far as possible esteem controller guarantees that the VFD framework isn't over-burden. This is reached out by the astute current points of confinement portrayed in the past section. As far as possible esteem controller decreases the heap on the VFD, e.g. amid increasing speed, by halting the quickening incline. The turn off of the variable recurrence drive which happens when the increasing speed slopes have been set at an exorbitant inclination is in this way avoided.


The variable recurrence drive control conduct of as far as possible controller can be set by means of the relative part, parameter Amplification and the coordinating part, parameter Integral Time. In the event that, in uncommon cases, advancement of the controller parameters is required, continue with the accompanying advances:

               Change parameter Current Limit with a major advance, dissect the adjustments in the Scope.

               For a more unique conduct increment Amplification or potentially diminish Integral Time.

               For a less powerful conduct diminish Amplification and additionally increment Integral Time.

Behavior in motor operation:
On the off chance that the VFD current set by means of parameter Current Limit is surpassed, the initiated current point of confinement esteem controller will lessen the yield recurrence until the point when as far as possible is never again surpassed. The yield recurrence is decreased as a most extreme to the recurrence set by the parameter Frequency Limit. On the off chance that the present esteem dips under the variable recurrence drive Current Limit, the yield recurrence is raised back to the reference esteem.

Behavior in generator operation:
In the event that the VFD current set through parameter Current Limit is surpassed, the enacted current breaking point esteem controller will expand the VFD yield recurrence until the point when as far as possible is never again surpassed. The yield recurrence is expanded, as a most extreme, to the set Maximum Frequency. On the off chance that the current is underneath the variable recurrence drive Current Limit, the yield recurrence is decreased to the required reference esteem once more.

In a Scalar drive (V/Hz just), the drive releases a Voltage a Frequency as indicated by the speed you have chosen. In any case, the VFD has no clue regardless of whether that had the coveted impact on the engine and load; it does it's thing and trusts in the best. On the off chance that the heap ends up being more than the engine can deal with, the engine backs off, the slip increments and the engine pulls more present and makes more torque, yet this is a "messy" process, best case scenario. So basically the drive gives a yield, the heap makes a "blunder" in execution, yet the drive doesn't generally make a move. The final product isn't generally compelling.

In Vector control, the VFD utilizes input from the engine to see the blunder, at that point to decide the correct vector of voltage and recurrence to deliver precisely what is expected to adjust the mistake. It has a rapid processor to do the math and rapidly change the yield voltage and recurrence example to augment the torque and/or fix the speed control. Along these lines, you can work an engine at Breakdown Torque at any speed, even zero if vital.

Vector control can be proficient with outer input from encoders called Closed Loop Vector or Field arranged Control (FOC), as you are doing, or with what is called "Sensorless Vector Control" (SVC) or "Open Loop Vector Control". The two names are actually off base; there is dependably a sensor and it is constantly shut circle. Yet, the distinction is in that what is called SVC utilizes exceptionally delicate current sensors within the drive to observe precisely what is happening, and contrasting it with a scientific model it has made of the engine amid setup (the "tuning" methodology). The two techniques work fine, yet the SVC has one restriction; it can't watch the engine execution if the engine isn't moving, i.e. zero speed; like what you would need with a lift. FOC, where you have the encoder criticism, can do that.

So for you, Starting Torque will dependably be most astounding and repeatable with Vector control of any kind contrasted with Scalar control. On the off chance that you require it at Zero Speed since you are expecting to discharge a brake and you need full torque to start with, at that point you require FOC. If not, SVC will likely work fine and you won't require the encoder.

Life of Electrical cables

Power cables and all other cables are integral part of electrical system as power can’t be transferred into equipment’s without cables. There are so many cables available in the market and there are so many manufacturer using different technologies to manufacture cables.
Life of electrical cables is usually depends upon the environment in which cable is used such whether cable is laid in open air, In trenches, In conduits, In cable trays, No. of bends in cable, Type of load connected at cable end, number of daily start stops of load.
It has been observed that usually life of cables is 20-30 years depending upon applications for which it is used and maintenance of cables.
We hear everything the time — America's electrical framework is maturing. Combined with that reality, one of the issues that keeps on surfacing around this continuous exchange is knowing the quality of the country's mind boggling medium-voltage (MV) power cables network, given the way that the aggregate picture is at last obscure. In spite of the fact that this is a legitimate concern, late innovative advances have made the evaluation of electric utility and business electrical power frameworks considerably less toiled and convoluted. So, evaluating administration matured, MV control links (see What Is a Service-Aged Cable?) keeps on being an unstable subject among numerous in the business — with testing and information examination systems, test hardware producers, recurrence of testing, and capabilities of the testing associations raising the discussion.
What is a Service-Aged Cable?
A power link is regularly considered administration matured following five years of consistent administration. Amid this five-year time frame, a legitimately introduced control link should hint at practically no maturing or protection decay. After this period, it's essential to set up a condition appraisal routine to screen the links wellbeing.
By recognizing the electrical emphasize focuses and evaluating their seriousness, the office architect can decide the maturing and disappointment mode that will cause debasement or other harm that, after some time, could prompt a definitive disappointment of a link framework. He or she would then be able to utilize this data to choose the best system of assessment and testing methods for identifying and observing the foreseen maturing/disappointment mode.


MV control links are qualified by different producers to give a predefined life of somewhere in the range of 20 to 30 years of proceeded with benefit in ideal natural and working conditions. A large number of the MV control links working in business, electric utility, and mechanical areas can be presented to an assortment of natural and operational stressors, including raised temperature, high UV radiation, high moistness, water submersion, and presentation to clean, earth, and destructive contaminants.

Electromechanical powers coming about because of the entry of abnormal amounts of short out current through a power link can conceivably make mechanical harm link coat and protection material and link conductors. High-voltage worry from lightning strikes or power framework homeless people can likewise corrupt the dielectric quality of link protection. After some time, these stressors — or blends of stressors — can cause maturing and territories of protection emphasize focuses that will bring about a slow corruption of the link protection and coat materials.

In spite of the fact that these disappointment modes and abnormalities sound discouraging and might be to some degree concerning, rest guaranteed that the lion's share of existing link foundation in the United States has surpassed 40 years of administration life.

Disappointment modes

For links that do bomb early, their death can normally be ascribed to one of the accompanying disappointment modes:
Fractional release — A limited electrical release that exclusive somewhat connects the protection amongst transmitters and could conceivably happen neighboring a conduit. This marvel causes intemperate warming and debasement of the link protecting materials and additionally ionization of the air in the region of the present spillage. If not adjusted, this disappointment mode could disastrously corrupt into either of the following two disappointment modes.
Treeing — A name generally given to the tree-like disintegration engendered by electrical releases in a link protection or covering. Electrical treeing is characterized as tree-like developments, comprising of nonsolid or carbonized miniaturized scale channels, which can happen at pressure upgrades, for example, distensions, contaminants, or voids subjected to electrical worry for expanded eras. Water treeing is the aftereffect of concoction adjustments within the sight of dampness that can happen at pressure upgrades, for example, distensions, contaminants, or voids in polymeric materials subjected to electrical pressure and dampness.

Poor workmanship — Direct mechanical harm, for example, twisting, scraped spot, cutting, contact, misshapening, and puncturing (coming about because of establishment and upkeep exercises in and around the area of a link), is a potential purpose of disappointment. Link grafts are presented to an indistinguishable natural and operational worries from the links on which they are introduced. Since link grafts are built of a considerable lot of the same or comparable materials as the electric links on which they are introduced, these stressors can likewise cause maturing debasement of the polymer protecting materials utilized as a part of the link join. Moreover, alternate subcomponents that make up a link join (protecting tape, fillers, sleeves, protecting mixes, and pressure connectors) are additionally helpless to maturing debasement. An ineffectively introduced or planned graft can bring about numerous infiltration pathways for dampness into the inside of the join — not just around the join materials where they about the surface of the link protection, yet in addition through the harmed or broke external coat or protection.
Upkeep arranging
An office upkeep organizer should truly do his or her homework to legitimize the need to test the life saver of the electrical power framework — the MV control link. Performing booked occasional support on the electrical frameworks' circuit breakers, switchgear, defensive handing-off, and transformers is to some degree less convoluted and tedious than arranging a long-length blackout to perform testing and appraisal on the power links. Money related weights inside offices have made it hard to stop them down to execute line influence link testing philosophies. Luckily, more current advances exist that may enable us to broaden the link appraisal windows farther (months or, at times, years) with break bring down cost internet testing in the middle of the disconnected support testing cycles. Link testing can expand the blackout span and work cost of a blackout; be that as it may, if performed effectively, it can yield significant information about the maturing procedure of the MV control links.

Experts performing electrical tests and reviews ought to be prepared and fit the bill to comprehend the dangers related with working, exchanging, and keeping up electrical power hardware. These people should likewise be prepared, experienced, and equipped for leading the link testing, assessing the test information, and making an educated judgment on the proceeded with serviceability or non-serviceability of the links under test.

Time-based preventive upkeep show

The choice to take a blackout for a period based preventive upkeep approach will require much intending to distinguish particular link sets to test, investigate, and dissect. This arranging will require however much recorded data about the development and upkeep of the office as could be expected, including one-line outlines and maker information on the links to be tried.

The essential objective of any preventive support anticipate MV control links is to test and break down the general protection of the link and additionally to decide the serviceability of the extras through information slanting to forestall cataclysmic disappointments. In this manner, numerous choices about the testing procedure should be made, which is the place the debate starts.

Since a large number of the accessible analytic tests must be performed when the gear is disconnected, de-empowered, and disengaged from benefit, understanding the approach and the upsides and downsides related with each test technique is critical.

DC hello potential testing — This strategy depends on a wellspring of high DC voltage for the testing of links and different kinds of electrical gear.

         Pro — The DC hello pot test is a straightforward, to a great degree versatile, and moderately modest bit of test gear to buy and work. Since it's a straightforward pass or come up short technique, low ranges of abilities are required to play out the test, in addition to it's the slightest expensive of any of the strategies.

         Con — The DC hello there pot test can be a dangerous test when performed on benefit matured, MV link protection (according to an EPRI think about performed in the 1990s). This test system is likewise oblivious in regards to specific sorts of protection absconds and actuates space charges that can exasperate existing protection surrenders in matured expelled links. The EPRI think about additionally demonstrated that proceeded with DC testing of adjusted matured, MV links can quicken the maturing procedure of the links. Climatic conditions, for example, dampness and wind, can likewise influence spillage current readings.
Air conditioning greetings potential testing — This strategy utilizes AC high voltage for the testing of links and different sorts of electrical gear at a level more prominent than the appraised voltage of the tried hardware.
         Pro — The AC howdy pot test is viewed as a decent test for conductive and high-impedance deserts in links and does not initiate space charge. Proceeded with utilize for the most part does not make extra maturing impacts. It is broadly used to repeat unfaltering state AC benefit conditions and the first plant over-potential test.
         Con — The AC hello there pot test requires a significantly bigger power source than its DC partner and accompanies an inborn requirement for different work force on occasion, which makes it the most exorbitant test to run. In spite of the fact that this AC test can quicken the maturing procedure of the links, it commonly does as such at a much slower rate than DC. This test is by and large a "go" or "no go" test.

Low-recurrence (VLF) testing — This test utilizes an instrument like an AC over-potential test set yet utilizes a much lower yield recurrence than standard AC over-potential test sets.
         Pro — The VLF test is a straightforward, to a great degree versatile, and generally reasonable bit of test hardware to buy and work with low power necessities. It is viewed as a decent test for conductive and high-impedance abandons in links and does not prompt space charge. Proceeded with utilize for the most part does not quicken or make extra maturing impacts after the test is controlled; nonetheless, some current deformities may develop quickly, influencing the test to time short.

         Con — The VLF system has a moderately short history of use and is simply getting to be ordinary in the field. This technique can irritate existing protection deserts in matured expelled links. IEEE 400.2 gauges alert against use on benefit matured links with various imperfections. The hoisted voltage levels could make the deformities connect together. For the most part a "go" or "no go" test, the VLF test does not recreate benefit conditions or processing plant tests and is viewed as a dangerous test.

Power factor/dispersal factor testing — Insulation control factor is the proportion of genuine energy to obvious power. At the point when increased by 100, it is alluded to as the "percent control factor." The power factor of the spillage current in a MV control link gives data about the nature of the general link protection.

         Pro — In use for over 75 years, the power factor test is a standout amongst the most well-known tests performed on electrical contraption to decide state of the strong protection. In spite of the fact that the innovation has developed quickly finished the most recent 25 years, it's as yet in light of a similar fundamental idea.

         Con — The test set is respectably costly, and longer keeps running of link will require extra gear, for example, resonators, to broaden the link testing range. Likewise, the power factor test requires benchmark or past power factor test information to incline the outcomes. This procedure can recognize limited protection abandons, however absconds that are voltage ward may not be distinguished if the start voltage of the deformity is more prominent than the test voltage. Protection diminishes as the inalienably typical dielectric-misfortune and capacitance of the frameworks increments.

VLF scattering factor testing — Also known as "tan delta" testing, this test is performed by applying a voltage beneath the working voltage and after that retesting at a voltage somewhat over the working voltage.

         Pro — The tan delta is a basic, to a great degree versatile, and moderately modest bit of test gear to buy and work. This strategy is non-damaging when utilizing voltages up to 10% to 20% over the typical working reach and extremely viable/generally utilized for distinguishing water trees in expelled links. The test is a genuine symptomatic test, enabling the administrator to pick up signature information about the state of the link protection.

         Con — Tan delta comes about at 60 Hz can introduce off base link protection evaluations comes about, particularly on profoundly benefit matured power links. Test lengths are longer for every individual conductor contrasted with other test approachs.

Disconnected halfway release testing — Known as "disconnected PD testing," this test surveys the power links' protection and extras, distinguishing electrical trees, tainting, de-overlay, and other physical antecedents to disappointment.

         Pro — This test has a moderately short history of use and is simply as of late getting to be typical in the field. This approach is fit for testing up to 3 miles of energy link, with a few constraints because of development compose and conductor estimating. The test screens link protection reaction amid voltage application and precisely finds grafts, joints, inconsistencies, and correct PD areas on a conductor. The test is compelling with blended dielectric conveyors.

         Con — The disconnected PD test is constrained to control links with ceaseless metallic shields, requires broad blackouts for different arrangements of link, and is the most exorbitant to perform contrasted with different strategies. The innovation is still fairly a questionable subject in the testing field because of the prerequisite that the information commonly must be broke down off-site or by faculty other than those playing out the test. Also, a few specialists question whether the test is repeatable between testing cycles.

Time-based prescient support program

At the point when an electrical blackout is taken a toll restrictive or needs inner help, a period based prescient upkeep approach might be the appropriate response. This support system includes the way toward assessing the state of hardware by performing intermittent or constant (on the web) gear condition observing. Essentially, prescient support contrasts from preventive upkeep by constructing the upkeep require in light of an appraisal of the genuine condition. In any case, it can likewise be based off of a preset timetable. There is one key test strategy utilized with this approach.

Online fractional release testing — The "online PD test" is performed while the hardware is invigorated at ordinary working voltages and gives a depiction in-time test, which is pulled and sent to an outsider research center for investigation.

         Pro — This test is led under genuine working conditions — at regular temperatures, voltage feelings of anxiety, and vibration levels. It's a non-damaging test and doesn't utilize overvoltages that could unfavorably influence the hardware. Online PD testing is moderately modest contrasted with disconnected testing, which requires interference of administration and generation. This technique identifies and finds some embellishment and a couple of link absconds, however can likewise distinguish disappointments in different zones (i.e., switchgear and transport).

         Con — Online PD testing isn't adjusted; test comes about are not objective and have no practically identical information to plant tests or IEEE measures. Like disconnected PD testing, this innovation is still to some degree a disputable subject in the testing field because of the necessity that the information ordinarily must be broke down off-site or by work force other than those playing out the testing. Furthermore, a few specialists question whether the test is repeatable between testing cycles.


As MV control links keep on aging, pushing great past their underlying plan and establishment details, a mix of qualified tests will be expected to incline the maturing procedure and survey staying valuable life.

DC overpotential testing of administration matured, MV links is not any more the most wanted strategy. Air conditioning over-potential and AC VLF testing, which can develop some innate protection absconds and have a to some degree dangerous nature, appear to lose bias with numerous office proprietors. Online PD testing is starting to give little previews of pivotal data on the respectability of an electrical framework. Fractional release can be found, estimated, and recorded, recognizing links, switchgear, and even transformers that are near disappointment in the middle of routine testing cycles.

The mixing of different approachs appears to offer the best data on the wellbeing and maturing advancement of MV control links. Conceivable blends for benefit matured links could incorporate yearly online PD examining and investigation took after by three-year to five-year disconnected upkeep interims utilizing power factor/dispersal factor testing or tan delta/scattering factor testing.

Despite the system picked, it shows up there will be no lack of debate among the testing group. At last, most testing temporary workers are hoping to offer a qualified, repeatable, non-ruinous way to deal with drifting and breaking down electrical power link protection and adornment information for their clients.

Sunday, April 22, 2018

Types of Bushings and Voltage ratings

Bushings are very important component of Transmission system. These are used of providing insulation to equipment.
There are various types of bushings available in the market, bushings are classified according to following:-
(i)                  Type of insulating material used
(ii)                Type of construction
(iii)               Insulation inside bushing
Let’s discuss about the same:-
(i)           Type of Insulating Material Used:-
This classification depends primarily on the application of the bushing, i.e. the purpose for which bushing is used. These can be further classified as:-
(a)    Air-to-oil bushing
In this type of bushing there is air is used as insulation at one end on bushing and oil acts as insulation at other end. In these bushings oil end is approximately half as long as air end as oil dielectric strength is more than two times than air at atmospheric pressure.
(b)   Air-to-air bushing
In This type of bushing  air acts as insulation at both ends and is used for applications where at end is open to atmospheric conditions and other is at indoor conditions.
(c)    Air-to-SF6 bushings
This type of bushing is used for SF6 insulated circuit breakers.
(d)   SF6-to-oil bushings
This type of bushing is used as shift from SF6 bus ducts and oil filled equipment.
(e)   Oil-to-oil bushings
This type of bushing as transition between Oil bus ducts and oil filled equipment.
(ii)                Type of Construction:-
There are two types of bushings depending upon type of construction, these are classified as below:-
(a)    Solid Type bushings also known as Bulk type bushings
(b)   Capacitance graded bushings also known as Condenser type bushings
Let’s discuss about these:-
(a)   Solid Type bushings:-
The kind of bushing, is normally made with a focal conductor and porcelain or epoxy covers at either end and is utilized essentially at the lower voltages through 25 kV.  These bushings are generally utilized as a part of utilizations extending from little distribution transformers and circuit switchgears to vast generator venture up transformers and hydrogen-cooled control generators.
The essential impediment of the strong bushing is its capacity to withstand 60-Hz voltages over 90 kV. Henceforth, its applications are restricted to 25-kV hardware appraisals, which have test voltages of 70 kV. Late applications require low halfway release confines on the 25-kV terminals amid transformer test and have brought about additional limitations on the utilization of this sort of bushing.
Solid Type Buhsing

In these cases, either an extraordinarily outlined strong bushing, with one of a kind evaluating protecting that empowers low innate halfway release levels, or a more costly capacitance-reviewed bushing must be utilized.

(b)   Capacitance Graded Bushings:-
These bushings are utilized for basically all voltage evaluations over 25-kV voltage and has been utilized for bushings upto 1500-kV voltage.
Capacitance graded bushing

These bushings utilizes directing layers at foreordained spiral interims inside oil-impregnated paper or some other protection material that is situated in the space between the focal conductor and the protector.
Diverse makers have utilized an assortment of materials and techniques for making capacitance-evaluated bushings. Early techniques were to embed concentric porcelain barrels with metallized surfaces or overlaid pressboard tubes with installed conductive layers. Later outlines utilized conductive foils, commonly aluminum or copper, in oil-impregnated kraft paper.
An elective strategy is to print semiconductive ink (distinctive producers have utilized diverse conductivities) on all or a portion of the oil-impregnated kraft-paper wraps.
The primary components are the focal round conductor, onto which the capacitance-evaluated center is wound; the best and lower protectors; the mounting rib; the oil and an oil-extension top; and the best and base terminals.
Capacitance-reviewed bushings include numerous more specialized and assembling subtle elements than strong bushings and are hence more costly. These points of interest incorporate the protection/directing layer framework, gear to wind the capacitor center, and the oil to impregnate the paper protection.
In any case, it ought to be noticed that the outspread measurement required for the capacitance-evaluated bushing is considerably less than the strong development, and this saves money on material inside the bushing also in the mechanical assembly in which the bushing is utilized. Likewise, from a down to earth stance, higher-voltage bushings couldn't in any way, shape or form be fabricated with a strong development.

(iii)             Type of Insulation inside Bushing
Still another order identifies with the protecting material utilized inside the bushing. As a rule, these materials can be utilized as a part of either the strong or capacitance-evaluated development, and in a few sorts, more than one of these protecting materials can be utilized as a part of conjunction. The accompanying content gives a short portrayal of these sorts:
1. Air-Insulated Bushings
Air-protected bushings for the most part are utilized just with air-protected mechanical assembly and are of the strong development that utilizes air at air weight between the conductor and the protectors.
2. Oil-Insulated or Oil-Filled Bushings
Oil-protected or oil-filled bushings have electrical-review mineral oil between the transmitter and the encasings in strong sort bushings. This oil can be contained inside the bushing, or it can be imparted to the contraption in which the bushing is utilized. Capacitance-reviewed bushings likewise utilize mineral oil, typically contained inside the bushing, between the protecting material and the protectors for the motivations behind impregnating the kraft paper and exchanging heat from the directing lead.
3. Oil-Impregnated Paper-Insulated Bushings
Oil-impregnated paper-protected bushings utilize the dielectric cooperative energy of mineral oil and electric evaluations of kraft paper to deliver a composite material with predominant dielectric-withstand attributes. This material has been utilized broadly as the protecting material in capacitance-evaluated centers for approximately the most recent 50 years.
4. Gum Bonded or - Impregnated Paper-Insulated Bushings
Gum fortified paper-protected bushings utilize a sap covered kraft paper to manufacture the capacitance-reviewed center, while gum impregnated paper-protected bushings utilize papers impregnated with tar, which are then used to create the capacitance-evaluated center. The last kind of bushing has prevalent dielectric attributes, equivalent with oil-impregnated paper-protected bushings.
5. Cast-Insulation Bushings
Cast-protection bushings are developed of a strong thrown material with or without an inorganic filler. These bushings can be both of the strong or capacitance-evaluated types, despite the fact that the previous sort is more illustrative of present innovation.
6. Gas-Insulated Bushings
Gas-protected bushings utilize pressurized gas, for example, SF6 gas, to protect between the focal conductor and the rib. It utilizes the same pressurized gas as the electrical switch, has no capacitance reviewing, and utilizes the measurements and situation of the ground shield to control the electric fields.
Bushing rating and mounting are depended upon type of interface.  HT Bushing above 1000 V are designed as per IS 2099
There are 5 types of interfaces:-
Bushing Interfaces

1.       Interface A1
2.       Interface B1 & B2
3.       Interface C1 & C2
4.       Interface D1 & D2
5.       Interface F1, F2 & F3
Short circuit ratings of all above mentioned bushings is as below:-
Interface Type
Contact Type
Current Rating(A)
Peak asymmetrical current rating kA
1 Sec
2 Sec
3 Sec
Pin and Socket
Pin and Socket
Pin and Socket

Applications of different types of bushings:-
A1 Interface type bushings :-
These types of bushings are useful for equipment insulated with oil fluids such as Transformers, Switchgear, Capacitors.  There are following types of A1 interface type bushings:-
(i) 180AR-1
Voltage Rating- 12 KV, Current Rating- 250A, Dimensions are- 222 X 106 (height X Breadth)
(ii) K180AR-1
Voltage Rating- 24 KV, Current Rating- 250A, Dimensions are- 222 X 106 (height X Breadth)
(iii) 180AR-2
Voltage Rating- 12 KV, Current Rating- 250A, Dimensions are- 284 X 168 (height X Breadth)
(iv) K180AR-2
Voltage Rating- 24 KV, Current Rating- 250A, Dimensions are- 284 X 168 (height X Breadth)
(v) 180AR-3
Voltage Rating- 12 KV, Current Rating- 250A, Dimensions are- 171 X 55 (height X Breadth)
(vi) K180AR-3
Voltage Rating- 24 KV, Current Rating- 250A, Dimensions are- 171 X 55 (height X Breadth)
There is another interface A1 bushing known as In-Air bushing for dry type transformers, Motors , Switchgear and capacitors.
Types of Bushings are
(i)                  180A-24P-O
Voltage Rating- 12 KV, Current Rating- 250A, Creepage Distance (mm)- 630 mm
(ii)                180A-24P-O
Voltage Rating- 24 KV, Current Rating- 250A, Creepage Distance (mm)- 630 mm
Interface B Type Bushings:-
This is useful for Oil fluids such as Transformer, Switchgear & Capacitors.
There are following types of bushings:-
(i)                  400T1
Voltage Rating- 12 KV, Current Rating- 400A
(ii)                K400T1
Voltage Rating- 24 KV, Current Rating- 400A
(iii)               M400T1
Voltage Rating- 36 KV, Current Rating- 400A
(iv)              400AR-1
Voltage Rating- 12 KV, Current Rating- 400A
(v)                K400AR-1
Voltage Rating- 24 KV, Current Rating- 400A
(vi)              M400AR-1
Voltage Rating- 36 KV, Current Rating- 400A
(vii)             400AR-2
Voltage Rating- 12 KV, Current Rating- 400A
(viii)           K400AR-2
Voltage Rating- 24 KV, Current Rating- 400A
(ix)              M400AR-2
Voltage Rating- 36 KV, Current Rating- 400A
(x)                400AR-8
Voltage Rating- 12 KV, Current Rating- 250A
(xi)              K400AR-8
Voltage Rating- 24 KV, Current Rating- 250A
(xii)             M400AR-8
Voltage Rating- 24 KV, Current Rating- 250A
There is another type of Interface B type switch is specifically used for SF6 circuit breakers.
Similarly there are other Interface type bushings and have same applications only difference is in their mounting designs , voltage rating and current rating.