Power factors

Single-phase active power = El cos 0 Three-phase active power = (3) EI cos 0 where 0 = power factor angle, radians or degrees 

Single-phase reactive power = El sin 0 Three-phase reactive power = (3) EI sin 0 

Power factor is the ratio of the active power to the apparent power  

When the power factor is less than unity, there is reactive power present. In other words, more power is required to produce the work than is absolutely necessary. This translates into higher energy cost and larger 

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Dielectric constant (60 Hz) Dielectric constant (10 Hz) Dissipation (power) factor (60... 

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 ... 

Power cables Power cycles Power factor Powerforming... 

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. 

Several glasses have been developed with exceptionally low power factors of less than 0.015% at room temperature and 1 MHz. Figure 10 shows the variation of power factor with temperature. 

Fig. 10. Power factor at 1 MHz vs temperature for some commercial glasses. Courtesy of Corning Inc. The power factor is the ratio of the power ia watts dissipated ia a material to the product of the effective siausoidal voltage and current ia volt-amperes. When the dissipation factor is less than 0.1, the power...

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 a sample is determined from the capacitance and resistance values by means of the following relationship, where P = power factor, G = conductance in mhos (reciprocal ohms), W = x. frequency, and C = capacitance. 

Typical power factors for an EPR-based compound employed for 5—35 kV power cable is approximately 0.03—0.05% when measured at room temperature and about 1.0—1.4% measured at 90°C. 

Power factor, like the dielectric constant, is a property that represents a power loss that takes place when a wire insulation becomes the dielectric of a condenser because of a surrounding sheath or other conducting medium. 

Power factor losses under certain conditions cause a temperature rise in the insulation that may result in failure or reduced life of the insulation. In communication wiring the power factor of the insulation plays an important role. Here the actual power loss can represent an appreciable portion of the total energy in the circuit. In addition, this loss disturbs the circuit characteristics of the equipment at both ends of the line. 

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). 

In the second method, the pump and the motor are coupled direcdy, and either power (in kilowatts) or the current, I, and voltage, U, ate measured at the motor terminals. To determine the power actually transmitted into a pump, the motor power factor (PF) and efficiency (Eff ) must be known. These values ate usually taken from the motor manufacturer s caUbration curves (17). 

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. 

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