Electrical power factor

Where a o is referred to as the electrical power factor, with a, the Seebeck coefficient, a the electrical conductivity and X. is the total thermal conductivity. The figure-of-merit is often expressed in its dimensionless form ZT wWe T is absolute tenperature. 

Dielectric strength, kV mm Electrical Volume (dc) resistivity, ohm-cm Dielectric constant (60 Hz) Dielectric constant (10 Hz) Dissipation (power) factor (60 Hz) Dissipation factor (10 Hz) Mechanical Compressive modulus, 10Mb in-2 9.8-12 24-31 16-24 1014-1016 4.5-6.0 19 335-600 14 ... 

A.m blent Environment. The environment around the flow conduit must be considered in meter selection. Such factors as the ambient temperature and humidity, the pipe shock and vibration levels, the avadabiHty of electric power, and the corrosive and explosive characteristics of the environment may all influence flow meter selection. Special factors such as possible accidental flooding, the need for hosedown or steam cleaning, and the possibiHty of lightning or power transients may also need to be evaluated. 

Power Supplies and Controls. Induction heating furnace loads rarely can be connected directiy to the user s electric power distribution system. If the load is to operate at the supply frequency, a transformer is used to provide the proper load voltage as weU as isolation from the supply system. Adjustment of the load voltage can be achieved by means of a tapped transformer or by use of a solid-state switch. The low power factor of an induction load can be corrected by installing a capacitor bank in the primary or secondary circuit. 

Electrical. Glasses are used in the electrical and electronic industries as insulators, lamp envelopes, cathode ray tubes, and encapsulators and protectors for microcircuit components, etc. Besides their abiUty to seal to metals and other glasses and to hold a vacuum and resist chemical attack, their electrical properties can be tailored to meet a wide range of needs. Generally, a glass has a high electrical resistivity, a high resistance to dielectric breakdown, and a low power factor and dielectric loss. 

The most important electrical properties of insulation are dielectric strength, insulation resistance, dielectric constant, and power factor. Corona resistance, although not stricdy an electrical property, is usually considered also (10). 

The power factor of polyethylene which provides the measure of the power loss in the insulated conductor increases slightly with an increase in the temperature of the atmosphere or the electrical equipment, both of which may fluctuate widely. It also increases slightly with an increase in the humidity of the surroundings. 

Sheet Miea. Good quahty sheet mica is widely used for many iadustrial appHcations, particularly ia the electrical and electronic iadustries, because of its high dielectric strength, uniform dielectric constant, low power loss (high power factor), high electrical resistivity, and low temperature coefficient (Table 6). Mica also resists temperatures of 600—900°C, and can be easily machined iato strong parts of different si2es and shapes (1). 

The primary siting factors which influence the selection of a plant location are as follows environmental considerations, labor avadabihty and productivity, raw material avadabihty, proximity to market, property cost, accessibdity to transportation, tax iacentives, electric power avadabdity and cost, and living conditions. 

Sufficient titanate leads to a fully hardened polymer. Using only enough titanate to react with free hydroxyls, the resin may subsequently be cured at lower cost with conventional cross-linking agents. The titanated epoxy resin has a low power factor, which is important in electrical appHcations, eg, potting components and insulation (see Embedding). Titanates improve adhesion of metals to epoxies. 

Most large electrochemical processing faciHties are located where raw materials, including electric power, are readily available at reasonable costs. Other factors influencing the location of electrochemical plants are proximity to markets, estabHshed transportation faciHties, availabiHty of water, and a source of labor. Large electrochemical plants are capital intensive, requiring large capital investment cost per employee. 

Electrical. The plant electrical system is sometimes more important than the steam system. The electrical system consists of the utihty company s entry substation, any ia-plant generating equipment, primary distribution feeders, secondary substations and transformers, final distribution cables, and various items of switch-gear, protective relays, motor starters, motors, lighting control panels, and capacitors to adjust power factor. 

Dielectric Constant, Power Factor and Structure 111 Table 6.1 Typical electrical properties of some selected plastics materials at 20°C... 

In the case of polymer molecules where the dipoles are not directly attached to the main chain, segmental movement of the chain is not essential for dipole polarisation and dipole movement is possible at temperatures below the glass transition temperature. Such materials are less effective as electrical insulators at temperatures in the glassy range. With many of these polymers, e.g., poly(methyl methacrylate), there are two or more maxima in the power factor-temperature curve for a given frequency. The presence of two such maxima is due to the different orientation times of the dipoles with and without associated segmental motion of the main chain. 

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