Polyethylene insulation

A. Barlow, "The Chemistry of Polyethylene Insulation," IEEE Electrical Insulation Magacjne, 8—19 (1991). 

NEMA WC7/1991 (ICEA 5-66-524) Cross linked polyethylene insulated wire and cable for the transmission and distribution of electrical energy ... 

Chrysler MS 8288 Cable Primary, Thin wall cross-linked polyethylene insulated, Chrysler Corporation Engineering Standard No. MS-8288, 2004. 

Figure 8.10 PD intensities and tan S values versus test voltage for a cross-linked polyethylene insulated cable (according to [30]).

Electrical trees are essentially breakdown channels whose size, typically 50 to 200 microns, together with the large variations in impurity concentrations in the surrounding polyethylene, makes the identification of the impurities associated with both kinds of trees very difficult by traditional techniques. The use of micro-PIXE for the location and analysis of trace elements in electrical and water trees found in the polyethylene insulation of high voltage cables will be described. 

Bow Tie Trees. An example of the use of the microbeam to investigate the contaminants in a bow tie tree in polyethylene insulation is presented in figure 7 which shows a) the spectrum from the center of the tree, b) the average of spectra from the insulation outside the tree and c) the difference spectrum. The latter clearly shows the presence of aluminum, possibly a shard from the manufacturing process, as well as excess sulphur, chlorine, potassium, calcium, copper and possibly iron. 

In studies where a knowledge of the diffusion of metallic ions in polymers is important, one often wishes to measure a profile of the concentration as a function of depth. Neutron activation cannot be used to measure these profiles directly, but if the sample can be cut into thin slices with a microtome, these can be analysed individually to construct the profile. In our laboratory this technique is used extensively to study the migration of ions into the polyethylene insulation of high-voltage cables (10). These impurities contribute to the degradation with use of the electrical properties of the cable. 

Manufacturers of various fillers continue studies on altemative systems. Most antimony oxide used as a fire retardant can be replaced by a combination of zinc borate without the loss of other properties (in some cases improvements are reported). Another option is to use the same filler systems which are used in polyethylene insulated cables and wires. These are based on magnesium hydroxide and aluminum hydroxide. These systems pcrfoim as flame retardants but require a high filler concentration which affects jacket resistance and mechanical performance. Recently, new coated grades have been developed which can be used at up to 65 wt% without the loss of properties or productivity (extrusion rates 2,500 m/min of cable are possible). ... 

The enclosed strip apparatus requires more skillful construction, because the cooling plate on which the filter paper sheet is positioned must be manufactured with a uniform flatness to achieve a precision within 0.002 mm [11,12]. The plate itself is usually made of aluminium and the filter paper sheet is uniformly pressed to it during separation by a pressure of about 1 atm/cm. Cooling is effected by tap water running through the labyrinth of channels of the cooling plate. Buffer vessels are placed at each end of the plate and are equipped with screened platinum electrodes. Contacts between the filter paper sheet on the plate and electrode vessels is materialized by means of thick filter paper wicks (Whatman 3 MM) moistened with the buffer solution. The filter paper sheet is not positioned directly on the cooling plate, but is isolated from both sides by a polyethylene insulation foil. 

BS5468 Cross-linked polyethylene insulation of electric cables. 

Goto T. Material recycling of silane cross-linked polyethylene insulated cable using supercritical alcohol. Electrical Insulation News in Asia [trade journal— Institute of Electrical Engineers of Japan] October 2006. 

Oxidative induction time (OIT) provides an index useful in comparing the relative resistance to oxidation of a variety of hydrocarbon materials. The OIT procedure was first developed in 1975 by Gilroy and coworkers at Bell Laboratory as a test procedure to screen polyethylene insulation used in telephone wire and cable for its oxidation resistance. The method first became available as a Western Electric Specification and later as ASTM Test Method for Copper-Induced Oxidative Induction Time of Polyolefins. Polyolefin manufacturers quickly embraced the procedure and began to apply it to other applications including raw resins, finished pipes, wire and cable insulation, and, most recently, geosynthetic waste pit liners (ASTM D3895 2009). 

Fig. 1.1 An early transvenous ventricular pacing lead Elema 588 (Elema-Schonander, Solna, Sweden, later Siemens Elema, and now St Jude Medical). Left Central Terylene core, at least three stainless steel ribbon conductors and polyethylene insulation. Right The electrode was very large and there were no fixation devices. The lead was over 100 cm long to allow tunneling from the subclavicular region to the abdomen, where a connector was attached and the pulse generator buried. (Permission for use St Jude.)...

The cables in the modem telecommunication plant, which is to a large extent today s plant, contain polyethylene-insulated... 

The conductivity measurements at the highest pressure were performed in Australia by Hamann and Linton (Hamann and Linton, 1969) using an explosive, shock-wave technique at very short duration (Hamann and Linton, 1966) which allowed the use of polyethylene insulators. The authors performed electrical conductivity measurements of pure water and simple salts up to 10 GPa. 

Plastics have traditionally been thought of as insulators. In fact, electric wires are generally covered wilh a coating of polyethylene insulation. Now, some plastics have been found to be as conductive as metals. In chemistry, certainly, it pays to keep an open mind ... 

In 1968 cellular polyethylene insulation fully filled with petroleum jelly was introduced. The new cable was smaller in diameter and lighter in weight making it easier to handle. It is now used in all new installations. 

Water treeing arises with polyethylene insulated cables in wet conditions and at modest voltages where water diffuses into the insulation and, under particular conditions, forms fine chaimels. Wright (9) notes that this has also been seen in EPDM rubbers and he also cites a case of automotive cooling hose where a voltage was apparently generated by electrochemical processes between the coolant and metals in contact with the coolant. This makes a good example of a case where the most unexpected occurred. 

For example, the requirements for PE insulation and sheathing for telecommunications (types 03 and 2), radiofrequency cables (type 03 and 2), and electricity supply cables (type TE, TSj and TS2) are given in Tables 12 14. All telecommunication and radiofrequency types of polyethylene insulation and sheathing are discussed in BS 6234. 

TABLE 11 Mechanical properties of polyethylene insulation in the 30.75° class... 

Barlow A. The chemistry of polyethylene insulations. IFFF Electr Insul M 1991 7 8. 

The development of high strength thermoplastic adhesive copolymers of the EAA type containing reactive carboxyl groups has made it practical to bond insulation such as polyethylene to metal conductors to provide adequate bonding and long term environmental resistance. Frequently, the EAA copolymer is extruded around the cable. Peacock reports that when a layer of acrylic acid-ethylene copolymer (7 43) was extruded at 140°C over a flexible aluminum conductor followed by a layer of polyethylene insulation, the bond strength between the insulation and the conductor was 72 N/cm compared with 1.4 N/cm for a control assembly without the copolymer adhesive. There are numerous similar patent claims for insulated conductor cable. 

Plastic Film, Polyester, Polyethylene Coated (For I.D. Cards) Plastic Tubes and Tubing, Heavy Wall, Teflon TFE Resin Thermoset Epoxy Resin Sheet, Paper Reinforced Insulation Tape, Electrical, Pressure Sensitive, Telfon TFE Resin Plastic Material for Molding and Extrusion, High Density Polyethylene and Copolymers Insulation Sleeving, Electrical, Flexible, Heat-Shrinkable Film Tape, Pressure Sensitive Plastic Sheets, Virgin and Borated Polyethylene Insulation Tape, Electrical, High Temperature, Teflon, Pressure Sensitive... 

Methods of Testing Poljaneric Films Used for Electrical Insulation Specification for Polyethylene Insulated Wire and Cable... 

---