FIELD OF THE INVENTION:
The present invention generally relates to insulation of poles in switchgears, more particularly, the shroud for pole encapsulation in medium voltage (MV) switchgears.
BACKGROUND OF THE INVENTION:
The apparatus used for switching, controlling and protecting the electrical circuits and equipment is known as switchgear. The switchgear covers a wide range of equipment concerned with switching and interrupting currents under both normal and abnormal conditions. Switchgears are two types as outdoor type and indoor type. Specially talking about the indoor type switchgear, it is generally of metal clad type. In this type of construction, all live parts are completely enclosed in an earthed metal casing. Primary object of the practice is the definite localization and restriction of any fault to its place of origin.
Moreover, medium voltage (MV) switchgear must handle higher levels of electrical energy and be capable of interrupting higher fault currents, it is larger and heavily constructed. Most electrical appliances used in household, commercial and industrial applications work with low voltage and also used for regional power distribution. While distributing power in various electrical appliances, there are lot of problems raised in MV switchgear.
The switchgear is incorporated with a withdraw-able trolley having 3 nos. poles which have separate top and bottom jaw contacts, and is always connected by vacuum interrupters. These pole units carry high voltage supply. To cover the open poles, shrouds are mounted on the poles. These shrouds are made by an external layer of insulation solution. In the prior art, up to 36kV switchgear uses the conventional shroud. But due to space and design constraint in moving portion, the air clearance is lesser than the recommended values. Other than that various problems may occur such as high voltage flashovers which may lead to personal injury or death.
The prior art document as given in the patent no. CN204760861U discloses the solution of the problem faced by the indoor switchgear circuit breaker which is having high voltage bushing without a safety measurement for human as well as machine. The patent

discloses an insulating guard shield for indoor switchgear of 35kV. The cylindrical shaped shroud is used to cover the ring gear of the transformer for providing safety measures in the indoor conditions. The patent does not solve the problem of air clearance due to space and design constraint in moving portion as discussed earlier. However, the above disclosed insulating guard shield of 35kV is cylindrical shape shroud and made by conventional materials thus lacks in flexibility.
In the prior art, the conventional shrouds are used to cover the higher voltage supply poles of switchgears to avoid any accident due to either by human errors or electrical faults. The poles shrouds are made by using different types of insulation methods which are used for phase-phase or phase-earth insulation method used in switchgears appliances. The following conventional methods are used in several medium voltage switchgear applications as:
a) Silica filled epoxy molded bushings
b) Ceramic material insulation
c) SMC (Single molded compound) sheets
d) DMC (Dough molded compound) spouts
e) Fiber glass resin bonded laminated sheets
The problem with the Silica Filled Epoxy molded bushings is that the material used as Epoxy which is very brittle material and also very heavy to handle. There are also assembly issues and also low production rates and has high material cost. The conventional shroud is shown in figure 1(a).
The problem with the Ceramic material insulation is that the material used as ceramics are highly brittle and very bulky. It is not possible to design indoor switchgear encapsulation with ceramics and has high material cost. This conventional shroud is shown in figure 1(b).
The problem with the Single molded compound sheets is the sheet used as SMC are very hygroscopic in nature prone to water absorption. It is inflammable in nature and also has low insulation properties. Design of encapsulation with this material is very difficult. This conventional shroud is shown in figure 1(c).

The problem with the Dough molded compound sheets is the sheet used as DMC has very low electrical insulation properties. It is bulky to handle and also having assembly issues as shown in figure 1(d).
The problem with the Fiber glass resin bonded laminated sheets is the sheet used as Fiber glass laminated sheets which can be only used as phase barriers but cannot be formed as encapsulation of Switchgears. The sheet is inflammable & toxic in feature and also very low production rate as shown in figure 1(e).
Therefore, there is a need to configure a flexible shroud encapsulation in such a manner, that, the above mentioned drawbacks of conventional shrouds are addressed.
OBJECTS OF THE INVENTION:
It is therefore, the object of the invention to overcome the aforementioned and other drawbacks existing in prior arts.
The primary object of the present invention is to propose a pole shroud to provide insulation having higher reliability, redundancy and better aesthetics.
Another object of the present invention is to eliminate the damages, rejections and risks of toxicity and hazardousness.
Still another object of the present invention is to reduce the assembly time and labor, so that to increase the speed of production.
Yet another object of the present invention is to reduce the overall material cost and achieving higher lifecycle of switchgear.

SUMMARY OF THE INVENTION:
One or more drawbacks of conventional arts for covering the poles used in the indoor switchgear are overcome, and additional advantages are provided through the present invention as disclosed. Additional feature and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be part of the claimed disclosure.
In an embodiment, a pole shroud for encapsulating one or more poles supported on a support structure attached to a moving portion of switchgears, the pole shroud comprising: a shroud body opened at one end by collar joint, said collar joint shaped in such a manner that to be mounted removably and fittingly on the pole, said shroud body having walls and corners with optimum dielectric strengths.
In an embodiment, a pole shroud is made in such a manner that perfectly matched to shape of the pole and the said shroud body is made of PVC (Poly vinyl chloride) resin insulation. The minimum dielectric strength of the pole shroud body is 13kV/mm. The collar joint of the pole shroud is sealed to the shroud body by nylon snap fit screws/buttoned joints. The pole shrouds are used to cover switchgears wherein, these switchgear are at least one of a 12kV switchgear and a 36kV switchgear.
The present invention is customized according to size and shape of the shroud in such a manner that it can capable of high voltage insulation, and also provide fire proof insulation along with very high redundancy and reliability, and also increased production rate and lowest manufacturing cost.
Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of shrouds that are consistent with the subject matter as claimed herein, wherein:
Fig 1(a) - illustrates the conventional shroud made by insulation methods using Silica filled epoxy molded bushings.
Fig 1(b) - illustrates the conventional shroud made by insulation methods using Ceramic material insulation.
Fig 1(c) - illustrates the conventional shroud made by insulation methods using DMC (Dough molded compound) spouts.
Fig 1(d) - illustrates the conventional insulation methods using SMC (Single Moulded Compound) sheets.
Fig 1(e) - illustrates the conventional insulation methods using Fiber glass resin bonded laminated sheets.
Fig. 2(a) illustrates the poles (RYB) placed on medium voltage switchgears according to present invention.
Fig 2(b) illustrates the views PVC pole shrouds indicating with shrouds body and buttoned joint of the pole shroud and moving portion of the switchgears used in 12kV and 36kV switchgears according to the present invention.
Fig (3) illustrates the views of PVC pole shrouds parts used for covering poles of both 12kV and 36kV switchgears according to the present invention.
Fig (4) illustrates the views of PVC pole shrouds used for covering RYB pole of switchgears according to the present invention.
The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative

embodiments of the structures illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION:
While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
The figures illustrate only those specific details that are pertinent to understand the embodiments of the present disclosure, so as not to obscure the disclosure with details that will be clear to those of ordinary skill in the art having benefit of the description herein.
The present invention is directed towards a poles shrouds used to cover three phase poles of 12kV and 36kV medium voltage switchgear. In the present invention, figure-2(b) discloses a pole shroud (1) for encapsulating one or more poles (6,7,8) supported on a support structure attached to a moving portion of switchgears, the pole shroud (1) comprising of a shroud body (2) opened at one end by collar joint (3) shaped such that to be mounted removably and fittingly on the pole, said shroud body (2) having walls and corners with optimum dielectric strengths.
Figure (2b) illustrates a pole shroud (1) are used to cover the 3-poles (RYB poles) (6, 7, 8) for both at least one of a 12kV switchgear and a 36kV switchgear. The pole shroud comprises a shroud body (2), collar joint (3) and buttoned joint (4) for covering the vacuum interrupter poles of the switchgear. The shroud body(2) is moulded by the Poly vinyl chloride (PVC) insulating dip which makes the shroud much better than the other existing insulating method. The shroud body (2) is having dielectric strength of 13kV/mm.
The buttoned joints (4) are same as nylon snap fit screws. The shroud body (2) is shaped such that to match perfectly the pole of the switchgear. The collar joint (3) is sealed to the shroud body (2) by nylon snap fit screws/buttoned joints. The shroud is mounted on

the poles by opening the shrouds from the joints. Joints with nylon button are provided in PVC pole shrouds to remove them from the switchgear poles easily as shown in fig-(2b).
As shown in the figure 2(a), the medium/high voltage switchgear is configured with the poles which uses three phases i.e. RYB poles (6,7,8) unit which carry high voltage supply. Switchgear panel consists of a fixed enclosure and a withdrawable vacuum circuit breakers (VCB) trolley (5). The moving portion consists of a movable trolley (5) which consists of a support structure which supports three numbers of vacuum interrupter poles (RYB)(6,7,8) as shown in figure 2(a).
Fig-3 illustrates the various parts of the pole shroud (1) is used in MV switchgears. The PVC pole shrouds (1) are opened at one end by collar joint (3) from the poles in the switchgears. The collar joint (3) is sealed to the shroud body (2) by nylon snap fit screws/buttoned joints (4). The pole shrouds (1) can be easily mounted on the poles by opening the shrouds from the joints and hence, the pole shrouds (1) does not require any special support. The present invention is also provided with correct location of opening the pole shroud where the minimum value of phase-phase or phase-earth air clearances for bare conductor are 120mm for 12kV switchgear and 320mm for 36kV switchgear.
As shown in the figure 4, the pole shrouds completely covers the high voltage carrying parts (RYB Poles) (6, 7, 8,) of the switchgear. The pole shroud (1) is configured in an optimum size and shape which does not affect by the epoxy insulators, as well as meets optimum cost. The advantages of the present invention is disclosed as below.
Advantages of the Invention:
PVC dip molded shrouds are better than conventional shroud made by above insulation techniques as discussed in the background in following respects:
• Capable of high voltage insulation
• It is flexible material hence always non-breakable. Any other existing insulation for the same application is breakable.

• Has better aesthetics
• It has non-hygroscopic insulation
• Non-toxic and non-hazardous
• Non-inflammable material which provides fire proof insulation.
• Has better tensile properties and light weight
• Very convenient in assembly and very safe in handling.
• Very high redundancy and reliability
• Has fastest production rate
• Has lowest manufacturing cost.

We Claim:
1. A pole shroud (1) for encapsulating one or more poles (6,7,8) supported on a
support structure attached to a moving portion of a switchgear, the pole shroud
(1) comprising:
- a shroud body (2) opened at one end by collar joint(3), said collar joint(3) shaped such that to be mounted removably and fittingly on the pole, said shroud body having walls and corners with optimum dielectric strengths.
2. The pole shroud (1) as claimed in claim 1, is shaped such that to match perfectly the pole.
3. The pole shroud (1) as claimed in claim 1, wherein the shroud body (2) is made of PVC (Poly vinyl chloride) resin.
4. The pole shroud (1) as claimed in claim 1, wherein the shroud body (2) having the dielectric strength of 13kV/mm.
5. The pole shroud (1) as claimed in claim 1, wherein the collar joint (3) is sealed to the shroud body by nylon snap fit screws (4).
6. The pole shroud(1) used to cover the high voltage poles of the switchgear as claimed in claim 1, wherein the switchgear is at least one of a 12kV switchgear and a 36kV switchgear.