Electrical insulation paper
Encyclopedia
Electrical insulation papers are paper
types that are used as electrical insulation in many applications due to pure cellulose
having outstanding electrical properties. Cellulose is a good isolator and is also polar, having a dielectric
constant significantly greater than one.
Electrical paper products are classified by their thickness, with tissue considered papers less than 1.5 mils thickness, and board considered more than 20 mils thickness.
needs to be. Paper machines are run with deionised or even distilled process water when producing higher grades of electrical insulation paper. Electrical insulation papers are made from well delignified unbleached kraft pulp
.
and current
used. Telephone cable
s have moderate voltage and current associated with cables leading moderate electric current or transmitting electrical signals. The telephone cables have a large number of conductors that are individually insulated. In order to not become excessively thick the paper needs to be thin (30-40 g/m2). A normal power cable needs more insulation and therefor paper with higher paper density is used, normally 60-190 g/m2. The paper needs to be strong, elastic, uniform and free of holes or debris. These applications are being replaced by plastic
insulation.
s at very high voltages (< 400 kV) are a very demanding application. The paper is normally 65-155 g/m2 and mostly produced on two ply paper machines. An advantage of using paper in sea cables is that in case of leakage, the paper will swell and prevent water from flowing along the cable.
s and is an extremely clean and thin tissue paper
(normally 6-12 g/m2) that is super calender
ed. The pulp
is clean unbleached kraft pulp that is extremely refined. The paper is made on small paper machines with slow speeds because the stock has to be drained very slowly.
up to 2 mm in thickness. The board is built up wet on forming cylinders and cut off when at the desired thickness. This makes a sheet with the size of the width and circumference of the drum. The wet sheets are dried and finished on separate machines.
In 1970, a branch of Weidmann
Electrical Industries centered in St. Johnsbury, Vermont
produced the largest Transformerboard ever measuring 12'5" by 21'8". At the time, the Vermont
-based company was named EHV Industries.
Paper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
types that are used as electrical insulation in many applications due to pure cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
having outstanding electrical properties. Cellulose is a good isolator and is also polar, having a dielectric
Dielectric
A dielectric is an electrical insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not flow through the material, as in a conductor, but only slightly shift from their average equilibrium positions causing dielectric...
constant significantly greater than one.
Electrical paper products are classified by their thickness, with tissue considered papers less than 1.5 mils thickness, and board considered more than 20 mils thickness.
Production
The more demanding application the cleaner the paperPaper
Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
needs to be. Paper machines are run with deionised or even distilled process water when producing higher grades of electrical insulation paper. Electrical insulation papers are made from well delignified unbleached kraft pulp
Pulp (paper)
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fibre crops or waste paper. Wood pulp is the most common raw material in papermaking.-History:...
.
Cable paper
Electrical cables are categorized by the voltageVoltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
and current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
used. Telephone cable
Twisted pair
Twisted pair cabling is a type of wiring in which two conductors are twisted together for the purposes of canceling out electromagnetic interference from external sources; for instance, electromagnetic radiation from unshielded twisted pair cables, and crosstalk between neighboring pairs...
s have moderate voltage and current associated with cables leading moderate electric current or transmitting electrical signals. The telephone cables have a large number of conductors that are individually insulated. In order to not become excessively thick the paper needs to be thin (30-40 g/m2). A normal power cable needs more insulation and therefor paper with higher paper density is used, normally 60-190 g/m2. The paper needs to be strong, elastic, uniform and free of holes or debris. These applications are being replaced by plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...
insulation.
High tension power cable paper
Submarine power cableSubmarine power cable
Submarine power cables are major transmission cables for carrying electric power below the surface of the water. These are called "submarine" because they usually carry electric power beneath salt water but it is also possible to use submarine power cables beneath fresh water...
s at very high voltages (< 400 kV) are a very demanding application. The paper is normally 65-155 g/m2 and mostly produced on two ply paper machines. An advantage of using paper in sea cables is that in case of leakage, the paper will swell and prevent water from flowing along the cable.
Capacitor tissue
This paper is used in capacitorCapacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...
s and is an extremely clean and thin tissue paper
Tissue paper
Tissue paper is a lightweight paper or, light crêpe paper. Tissue can be made both from virgin and recycled paper pulp.-Properties:Key properties are: strength, absorbency, basis weight, thickness , brightness, stretch, appearance and comfort....
(normally 6-12 g/m2) that is super calender
Calender
The calender is a series of hard pressure rollers used to form or smooth a sheet of material. In a principal application, the calender is located at the end of a papermaking process . Those that are used separate from the process are also called supercalenders...
ed. The pulp
Pulp (paper)
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fibre crops or waste paper. Wood pulp is the most common raw material in papermaking.-History:...
is clean unbleached kraft pulp that is extremely refined. The paper is made on small paper machines with slow speeds because the stock has to be drained very slowly.
Transformer board
Transformer board is used where an insulating structure is needed. This is a crêped boardCrêpe paper
Crêpe paper is tissue paper that has been coated with sizing and then creped to create gathers.-Production:Paper that is creped is produced on a paper machine that has a single large steam-heated drying cylinder fitted with a hot-air hood. The raw material is paper pulp. The Yankee cylinder is...
up to 2 mm in thickness. The board is built up wet on forming cylinders and cut off when at the desired thickness. This makes a sheet with the size of the width and circumference of the drum. The wet sheets are dried and finished on separate machines.
History
The use of paper board as electrical insulation paper started in the early-mid 20th century. Since the need for high voltage electrical transformers, there has been a need for an insulating material that could withstand the high electrical and physical stresses experienced around a core and windings. Pressboard, a board made by compressing layers of paper together and drying them, has been used for installation purposes in many of the first electrical machines. However as electrical technology increased, the need for a higher density material that was capable of insulating larger and higher voltage transformers grew. In the late 1920s, Hans Tschudi-Faude became the director of H. Weidmann Limited and began developing a type of pressboard that would meet the higher standards needed for the newer, more powerful transformers. Unlike older methods of pressboard production, Transformerboard was not based on used paper or cotton waste but was made with high-grade sulfate cellulose. The new product was made purely out of cellulose without a resin or binder, improving electrical insulation capabilities and could be completely dried, degassed, and oil impregnated. The new product became famous under the name Transformerboard. Throughout the 1930s, new methods of production and advances in understanding replaced almost all insulating parts of transformers with parts made from transformer board.In 1970, a branch of Weidmann
Weidmann
Weidmann is a German surname meaning "hunter". It may refer to:* Charles Weidman , American modern dancer, choreographer and teacher...
Electrical Industries centered in St. Johnsbury, Vermont
St. Johnsbury, Vermont
St. Johnsbury is the shire town of Caledonia County, Vermont, United States. The population was 7,571 at the 2000 census. St. Johnsbury is located approximately northwest of the Connecticut River and south of the Canadian border.St...
produced the largest Transformerboard ever measuring 12'5" by 21'8". At the time, the Vermont
Vermont
Vermont is a state in the New England region of the northeastern United States of America. The state ranks 43rd in land area, , and 45th in total area. Its population according to the 2010 census, 630,337, is the second smallest in the country, larger only than Wyoming. It is the only New England...
-based company was named EHV Industries.