FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
PROVISIONAL SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Safety Pole for Electrical power distribution
APPLICANTS
Name: CROMPTON GREAVES LIMITED
Nationality: Indian Company
Address: Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli,
Mumbai 400030, Maharashtra, India
INVENTOR
Name: Raghavan Venkatesh
Nationality: Indian National
Address: Crompton Greaves Limited, Switchgear-6 & Power Quality Business Unit, D2,
MIDC, Waluj, Aurangabad 431136, Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification describes the invention:

FIELD OF INVENTION
This invention relates to a safety utility pole for electric power distribution. This
invention also related to electric power systems for voltages upto 66 kV with safety utility poles.
BACKGROUND OF THE INVENTION
Utility line poles (upto 66kV) are generally made of wooden poles, as shown in figure 1. This comprises of a wooden pole with a metallic cross arm fixed to the wooden pole. The phase conductors are supported on insulators which are mounted on the cross arm. The insulators are conventionally of glass, ceramic or any other outdoor insulating material. The wooden poles are treated with special chemicals / resins to improve the durability.
The disadvantage with these types of poles are that the poles need to be treated with chemicals that environmentally questionable. Even with such treatments the poles are subjected to fungus, rot and animal attack. Another major disadvantage associated with such poles are that the main pole is not a very good electrical insulator and there is a possibility of a leakage current flowing on the surface of the poles, especially during wet conditions as encountered during rains, thus endangering the life of persons who may come in contact with the poles.
Another type of pole used is made of cement concrete of various sections such as circular, square, rectangular with or without tapering used in the place of wooden poles. This type of pole also requires the use of metallic cross arms and separate insulating parts to support the phase conductors and have the same disadvantage of the possibility of
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electrocution due to leakage current flowing on the surface of the pole. Such poles are depicted in figure 2.
Other kinds of poles include tubular metal poles, wherein the metal could be galvanized steel, aluminum alloy, cast Iron etc. All these poles also have the same disadvantages such as need for separate cross arm and insulating components and does not eliminate the possibility of an electrocution due to leakage currents flowing on the surface of the pole. Such poles are depicted in figure 3. Another variant shown in figure 4 uses solid steel section as the pole.
Another prior art describes a pole made with fiber reinforced plastic pole but has the disadvantage that this is expensive and also requires additional cross arms and support insulators and has the disadvantage of possibility of leakage current flowing on the surface of the pole leading to electrocution. Though the basic material may be a good insulator the surface resistance (resistivity) of such materials is not very high, especially during wet conditions and can permit a significant value of leakage current flowing on the surface.
Some of the other prior art are disclosed in the following US patents
6,286,281, 5,222,344, 5,749,198, 5,247,774, 5,024,036, 4,991,726, 4,809,146, 4,825,620,
4,715,503, 6,305,140, 5,784,851, 4,166,347, 6,167,673
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None of the prior art designs address the risk of electrocution due to flow of leakage current on the surface of the utility pole or have embodiments that indicate the status of the phase conductors to indicate if the line is live of not.
The disclosed invention is a composite utility pole, which eliminates the possibility of a leakage current flowing on the surface of the utility pole, and thus eliminates the risk of electrocution. The invention also eliminates the need for separate cross arms and separate pin or post insulators for supporting the phase conductors' of an electrical power distribution system.
An object of the invention is to provide safe utility poles for electric power distribution upto and including 66kVs which eliminates the possibility of electrocution due to leakage currents flowing on the surface of the poles.
Another object of the invention is to provide a utility pole for electric power distribution that does not require additional/separate cross arm and support insulators for supporting the phase conductors.
Another object of the invention is to provide a utility pole with an indication facility to monitor the status of the phase conductors to ascertain whether they are live or not.
Another object of the invention is to provide a utility pole with embedded capacitive voltage dividers to monitor the voltage on the phase conductors.
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DESCRIPTION OF INVENTION
According to the invention there is provided a safety utility pole for electric power distribution comprising of a metallic core embedded in a outdoor polymeric (polymer concrete) insulating material which is cast under vacuum and vibration.
The polymer concrete material is made of a special formulation comprising of a base polymer made of polyester, Acrylic or epoxy resin systems or a combination of such resin systems. Suitable catalysts such as methyl ethyl ketone peroxide or benzoyl peroxide or combinations of such catalysts are used in suitable proportions to create an exothermic reaction to polymerize the unsaturated system, which acts as a binder.
The resin is filled with appropriate filler materials such as graded silica, aluminum tri hydrate, Titanium Dioxide, clay, fly ash, chopped glass strands, glass fiber, Kevlar fibers, carbon fibers etc. in selected proportions to achieve the desired electrical, mechanical, thermal, physical and chemical properties.
The composition and the proportion of various materials is so chosen to achieve the desired electrical, mechanical, thermal, chemical and physical properties.
Special additives such as wetting & coupling agents such as Silane, UV stabilizers, plasticizers, accelerators such as cobalt solutions, are added to improve the mechanical and outdoor weathering properties.
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Typical composition by weight comprises of resin system in the proportion of 10% to 30%, coupling/wetting agents in the proportion of 0.1% to 2%, Graded silica in the portion of 50% to 80%, alumina trihydrate in the portion of 1% to 30%), Titanium dioxide in he portion of 0.1 % to 10%, and reinforcing elements such as glass fibers etc in the proportion of 0.01% to 20%. Additional filler materials such as fly ash, clay etc. are added in proportion of 0.005%) to 30% to get the required properties depending upon the application and specific property requirements.
The polymer concrete slurry is cast into desired shapes, which include the required electrical clearances and profiles (sheds) to enhance the outdoor electrical performance.
The casting is done under a vacuum with a pressure level in the range of 5 mm to 740 mm of Hg , in controlled temperature of 10°C to 75°C and the slurry is poured into a mound kept in vacuum, with pressure in the range of 5 mm to 740 mm of Hg, and controlled temperature in the range of 10°C to 75°C and is vibrated with an amplitude of 0.01 mm to 5 mm of vertical displacement with a frequency of 0.01 Hz to 400 Hz. The choice of process parameters such as Vacuum (pressure) level, temperature and vibration are controlled to get the desired properties and depends upon the shape and size of castings. The pouring rate of the slurry into the moulds is at a controlled rate of 0.1 kG to 10 kG per minute.
The polymeric reaction is exothermic and the temperature increase due to the exothermic reaction itself is used to complete the polymerization and cure the resin system. The
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temperature of the exothermic reaction is dependant upon the ambient temperature, resin system, proportion of various elements of the polymer concrete slurry, total mass of casting, material of mould etc. and is controlled to get the desired properties by controlling the proportion of various elements and the ambient temperature as to maintain the temperature in the range of 45°C to 120°C. This temperature range is adequate to completely cure the resin system without any additional heat input and is also low enough to be compatible with all materials used in the system for embedding or casting.
The mould is made of steel, aluminum, FRP or silicone rubber. The mould is preassembled with the metal parts to be cast into the polymer concrete. Suitable mould release agents are applied to the mould to facilitate easy mould release.
In the basic embodiment of the invention, there is provided a core made of a metal such as aluminum, steel, cast iron, copper, brass etc. which is cast / encapsulated with a special formulation of an outdoor polymeric insulating material, which forms the outer casing / sheathing. The inner core is designed as to provide the required mechanical strength and has a small disc attached to it, which protrudes out of the outer polymeric casing and acts as a current collector for the surface leakage current that may flow on the surface of the polymeric casing. The Polymeric casing is extended beyond the inner metallic core and is shaped and cast in such a way as to act as insulating arms to support the phase conductors of the transmission line. The ends of the supporting insulating members are provided with an arrangement to fix the phase conductors to the pole.
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According to another embodiment of the invention, the extended support members are cast with reinforcing insulating components such as FRP rods, glass fibers, glass fiber woven mats etc. as to increase the mechanical strength of the support member.
According to another embodiment of the invention, the cast support structure in one or many of the support arms has embedded capacitor elements as to increase the capacitive reactance of the phase conductors and thus reduce the inductive reactance of the phase conductor.
According to another embodiment of the invention, the integrally cast capacitor elements are configured as live line indicators to facilitate monitoring the status of the line to check if the phase conductors are live or not. The capacitor elements are connected between the phase conductors and the inner metallic core, which is connected to earth (ground). A small voltage appearing across the series connected capacitor elements, acting as a voltage divider, is taped and is taken to ground level and is connected to a suitable indicating device such as LED.
According to another embodiment of the invention, the integrally cast capacitor elements are configured as capacitive voltage dividers to facilitate measurement of phase to ground voltages.
According to another embodiment of the invention, there is provided a facility for tapping the power lines and routing the cables through the inner metallic core of the utility pole.
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In accordance with this invention, the Pole comprises of an integrally cast pole with insulating support arm for supporting the phase conductors with an internal metal core with a protrusion for collecting the surface leakage current and safely carrying to earth through the internal metal core.
Other embodiments of the invention are provided with reinforcing elements, with embedded capacitors to enhance capacitive reactance of the lines, act as live line indicators, as capacitive voltage dividers and tapping facility for running tapped power cables.
In prior art, wherein the high voltage phase conductors are supported on a pin/post insulator made glass or ceramic and mounted on metallic cross arms which are supported on wooden poles.
This design has the draw back of damage to wooden poles due to fungus, rot and animal bites. The other disadvantages associated with this design are the labour required to fix the cross arms and insulating supports at site before the line could be supported. The main disadvantage is that the leakage current that can flow on the surface of the pole under wet conditions can lead to electrocution of humans or animals in contact with the pole.
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In another prior art, wherein the high voltage phase conductors are supported on a pin/post insulator made glass or ceramic and mounted on metallic cross arms which are supported on concrete, tubular steel or solid steel poles. The disadvantages associated with these designs are the labour required to fix the cross arms and insulating supports at site before the line could be supported. The main disadvantage is that the leakage current that can flow on the surface of the pole under wet conditions can lead to electrocution of humans or animals in contact with the pole.
All prior art suffer from disadvantage that the leakage current that can flow on the surface of the pole is not eliminated and can lead to electrocution of humans or animals that can come in contact with the poles.
The invention is superior than the prior art designs as effectively conducts the surface leakage current through the insulated inner core thereby eliminating the possibility of an electrocution. This invention also eliminates the need metallic cross arms and separate support insulators thereby reducing the labour required in setting up these poles and reduces the time taken to set up distribution lines.
In another embodiment, the insulating support arms are manufactured with reinforcing elements such as glass fibers, glass fiber rods, glass mats etc. This enhances the strength of the support structure and facilitates supporting larger weights.
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In another embodiment of the invention, discrete capacitor elements connected in series are embedded in the insulating support arms. These capacitor elements provide for capacitive reactive reactance to compensate for the inductive reactive reactance of the phase conductors.
In another embodiment of the invention, the capacitors embedded in the support arm are configured as live line indicators, as to facilitate monitoring the status of the live thereby increasing the safety of operating personnel, who may be required to climb such poles for maintenance purposes.
In another embodiment of the invention, the capacitors embedded in the support arm are configured as capacitive voltage dividers, as to facilitate monitoring voltage on the lines for the purpose of monitoring, metering or protection.
In another embodiment of the invention, a provision is made in the pole for tapping power from the overhead lines and carrying this power to ground level through cables running inside the metallic core of the pole.
In accordance with the present invention, a utility pole for electric power distribution comprising of a cast pole made of outdoor polymer concrete insulating material with integral insulating support members for supporting the phase conductors with a internal
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metallic core for safely carrying the surface leakage currents to earth through insulated inner core.
In accordance with the present invention, the inner metallic core of this utility pole can be a solid rod or a hollow tube, can be made with materials such as mild steel, galvanized steel, stainless steel, aluminum, coper, brass etc.
In accordance with the present invention, a utility pole is provided with internal reinforcing elements such as glass fiber, glass mat, FRP rods etc. in the insulated support arm.
In accordance with the present invention, a utility pole is provided with embedded capacitors in the insulated support arm to reduce the inductive reactance of the power line to improve the efficiency of power transformer and the embedded capacitors are configured as live line indicators to indicate the status of the line to check if they are live or not.
In accordance with the present invention, the live line indicator of a utility pole, is provided with a LED driven by the current drawn for the phase conductors through the capacitive voltage divider.
In accordance with the present invention, the embedded capacitors of a utility pole are configured as capacitive voltage divider to monitor the voltage of the phase conductors.
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In accordance with the present invention, a utility pole is provided with a provision for tapping power from overhead utility lines and routing it through cables running through the inner core of the pole.
Dated this 30th day of March 2007

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