Motor power

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). 

Propeller size, pitch, and rotational speed may be selected by model tests, by experience with similar operations, or, in a few cases, by published correlations of performance data such as mixing time or heat transfer. The propeller diameter and motor power should be the minimum which meet process requirements. 

When the power defieit is eovered by an eleetrie motor, the initial motor load may be a multiple of its normal power output beeause the expander is unable to eontribute any power at startup. Depending on plant design and startup requirements, a motor power of 50%-75% of the rated eompressor power is suffieient for startup purposes. Careful engineering studies are always appropriate in this ease. 

Jeumont-Schneider, R. Champrade, High Power Adjustable Speed Ihr, with Synchronous Motor, Power Conversion International, Sept H i. . 1979, pp. 83-89. 

CRITICAL SPEED RECOMMENDED MOTOR POWER (UPi1[Pg.657]

Fail-safe Design features that provide for the maintenanee of safe operating eonditions in the event of a malfunetioning eontrol deviee or an interruption of an energy souree (e.g., direetion of failure of a motor-operated valve on loss of motor power). 

The 211 control rods were moved in and out of the core by winches driven by electric motors. Power and neutron flux distribution were measured by in-core self-powered ion chambers, which were inaccurate at lower power. At low power, ion chambers in the graphite reflector were used. 

MOTOR POWER OUTPUT, hp Range of Drive Loss for Standard Belts Higher Fan Speeds Tend To Have Higher Losses Than Lower Fan Speeds at the Same Horsepower... 

Power factor is another factor that should be considered in the selection of a motor. Power factor can be improved by the design of the motor or by the external addition of a... 

The usual synchronous motor power factors are unity (1.0) or 0.8 leading. Values of 0.7 or 0.6 leading will give more leading correction to an otherwise lagging system. 

Type of drive Power range (kW) Speeds Drive efficiency (%) Overall efficiency (%) including motor Power factor Main characteristics related to pump drives... 

Recent developments in electronic motor power and speed controls have provided the means to reduce the power input at normal speed to balance this reduced load requirement, and also to modulate both power and speed as a method of capacity reduction. It is improbable that electronic speed control will be economical for motors above 100 kW. 

The energy input of part of the plant must be included in the cooling load. In all cases include fan heat, either net motor power or gross motor input, depending on whether the motors are in the conditioned space or not. Also, in the case of packaged units within the space, heat is given off from the compressors and may not be allowed for in the manufacturer s rating. 

The main effects of a higher condensing temperature will be a drop in the refrigerating effect, since the liquid enters the expansion valve hotter, and a decrease in volume pumped due to the lower volumetric efficiency. There will also be an increase in the drive motor power. 

While obtaining test data, scale-up calculations should be made regularly to determine if the end results will be practical, particularly from the available mixing hardware, motor power, etc. 

These results fit with the general premises of mixing. Motor power requirements will increase with increasing time and RPM. In addition the increase in surface area of the rotor (i.e., that area... 

Flow Q Hgt. Material Head Pump Motor Power Ave. ... 

Besides fuel-cell (electric) vehicles (FCV), there are other vehicle concepts under development, which are also based on electric drives ranked by increasing battery involvement in the propulsion system, and thus extended battery driving range, these are hybrid-electric vehicles (HEV), plug-in hybrid-electric vehicles (PHEV) - which both incorporate an ICE - and, finally, pure battery-electric vehicles (BEV), without an ICE. While electric mobility in its broadest sense refers to all electric-drive vehicles, that is, vehicles with an electric-drive motor powered by batteries, a fuel cell, or a hybrid drive train, the focus in this chapter is on (primarily) battery-driven vehicles, i.e., BEV and PHEV, simply referred to as electric vehicles in the following. 

Figure 12.18 Schematic representation of a linear motor powered by light Adapted from V. Balzani, A. Credi and M. Venturi, Light-powered molecular-scale machines , Pure and Applied Chemistry Volume 75, No. 5,541-547 International Union of Pure and Applied Chemistry IUPAC 2003...

Finally, the concept of viscosity and resistance to flow of polymers as a function of shear rate will be discussed because there is often a misconception regarding the dissipation in an extruder at high shear rates when the viscosity is in the power law region. As previously discussed, the viscosity decreases as a function of increasing shear rate as shown in Fig. 3.23. Often this reduction in viscosity is misinterpreted as a reduction in the amount of power needed when the polymer is sheared at high rates. For an extruder, the misinterpretation would be that less motor power would be required to operate the machine at higher screw speeds. It... 

Extrusion processes are often rate limited by motor power or torque, discharge temperature, or the melting capacity of the screw. Other root causes associated with the design of the screw can limit rates as shown in previous sections. The problems, however, are typically associated with other defects such as flow surging or resin degradation. Chapters 11 and 12 discuss process defects associated with resin degradation and flow surging, respectively. Rate limitations due to inadequate motor power and torque are common problems for commercial plants. Two case studies are presented in the next sections that show rate limitations due to the lack of torque and motor power. 

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