Motor-generator

High sihcon steels (historically 3.75—5.00% but more recentiy 6% Si) are used in power transformers and high efficiency motors, generators, and transformers, and in communications equipment. 

Babbitt ahoys ate suitable for hundreds of types of iastahations involving the movement of machinery, eg, the main, crankshaft, connecting tod big end, camshaft, and journal bearings associated with marine propulsion, tailtoad and automotive transportation, compressors, motors, generators, blowers, fans, rolling-mill equipment, etc. 

One of the oldest adjustable-speed drives is the Ward-Leonard system. This consists of an ac to dc motor-generator set and a shunt or compound-wound dc motor. Speed is adjusted by changing the generator voltage. A functional equivalent of this drive uses an adjustable-voltage rectifier feeding a dc motor. This system has only one rotating machine in contrast to the three of a conventional Ward-Leonard system. 

Notching or jogging device (88, Auxiliary motor or motor generator... 

Additioiiiil noise from inductive equipment such as motors, generators md triinsformers and even overhead lines. 

Descending loads may overspeed the motor and iwerexcite the capacitor when connected across the motor due to motor generator action above the synchronous speed (Section 6.21). Such a situation may damage the motor as w ell as the capacitor and ntust be avoided. 

We say that the motor generates horsepower (HP), and that the pump consumes brake horsepower (BHp). The difference between HP (output) and BHp (input) is what is lost in the power transmission the bearings, shaft, and coupling between the motor and the pump. 

A power recovery train—occasionally called a string—(Figure 4-53) employing a turboexpander usually consists of four main elements or casings the expander, a motor-generator, an air blower, and a steam turbine. The steam turbine is used primarily for startup and often to supplement the expander for generation of energy. This topic will be discussed in more detail later in this chapter. 

The motor-generator ean either produee or absorb power. In some FCC units, the expander horsepower exeeeds the power needed to drive the air blower. In this ease, the exeess power is transmitted to the refinery power grid. If the expander generates less power than required by the blower, the motor-generator provides the power to hold the entire train at the desired speed. 

The motor/generator is modeled as an energy source/sink limited by its specific design capabilities. As a generator, it will absorb all excess power available while holding speed constant (synchronous) as long as it is electrically connected to the utility grid. 

Customer preference. Some hesitation exists to plaeing a motor/ generator between the eompressor and its main driver. In some eases, only direet-drive air strings are favored. 

String control in the event of motor/generator trip at full load. ... 

Sinee the generator is eonneeted to the eleetrieal grid, PRT speed is fixed. For induetion-type motor/generators, some speed variation is possible due to motor/generator slip, but this is only a small pereentage of rated speed. In any event, the speed eannot be used to eontrol other proeess parameters (e.g., air mass flow to the regenerator). 

To follow through with the open-loop approaeh, there must first be a signal that warns the speed eontrol funetion of load loss (or breaker opening) and impending speed inerease. This is provided by a digital eontaet that indieates motor/generator breaker status. Next, a load loss estimate is needed. This is provided by a kilowatt transdueer on the motor/generator. 

Calculating power developed by the expander before breaker opening, is described in Step 1. The generator power, can be measured by using a kilowatt transducer. The kilowatt transducer (or current transducer) is typically available in the motor/generator control panel. If not, it can be added to the machine at a low cost. Knowing both J(,gf and Jg, can be calculated. 

Items Expander Air blower Steam turbine Motor/ generator... 

As previously mentioned, FCC units produee hot flue gas as a byproduet. Hot gas is expanded in the expander turbine and then supplies meehanieal energy for proeessing. The exeess power is eonverted into eleetrieal energy by the motor-generator. Therefore, the power reeovery system is likely to raise the energy effieieney and profitability of the plant by substantial margins. 

The compressor train is driven by the motor/generator, which has a pair of clutches that enable it to act as a motor when the compressed air is being generated for storage in the cavern, declutches it from the expander train, and connects it to the compressor train. The compressor train consists of a three-section compressor each section having an intercooler to cool the compressed air before it enters the other section, thus reducing the overall compressor power requirements. 

The power train consists of an HP and LP expander arranged in series that drives the motor/generator, which in this mode is declutched from the compressor train and is connected by clutch to the HP and LP expander train. The HP expander receives air from the cavern that is regeneratively heated in a recuperator utilizing exhaust gas from the LP expander, and then further combusted in combustors before entering the HP expander. The... 

In synchronous motors, the excitation is supplied by a separate direct current source, either as a separate motor-generator (M-G) set or as an exciter mounted directly on the motor shaft. The current can be made to lead to various degrees by varying the magnitude of the field strength. 

Advise of exciter power characteristics available, or specify manufacturer to provide required exciter (small synchronous motors may use permanent magnets) as direct-connected, belt-driven, or motor-generator set. 

For speed ranges of 3 to 1 or greater, adjustable-voltage operation is recommended. The adjustable-voltage drive usually includes a motor-generator set to supply an adjustable voltage supply to the armature of the drive motor. With this method of operation, a speed range of 10 to 1 readily obtained. 

Almost every unique frequency contained in the vibration signature of a machine-train can be directly attributed to a corresponding mechanical motion within the machine. For example, the constant endplay or axial movement of the rotating element in a motor-generator set generates elevated amplitude at the fundamental (lx), second harmonic (2x), and third harmonic (3x) of the shaft s true running speed. In addition, this movement increases the axial amplitude of the fundamental (lx) frequency. 

The high voltage is obtained either by a step-up transformer from the mains, or a motor-generator set, or alternatively from batteries and a vibrator with a high-tension coil. The battery-operated instruments, are most popular as they are easily portable and most suited for field use. Such an instrument is illustrated in Fig. 10.53. 

Although at the time of his early inventions Dr. Schoop envisaged that an electric arc could be used to produce the molten metal for spraying, forty years passed before the method became commercially important. Then, in Germany, Russia and Japan tools were made based on the arc. Although in Japan alternating current is used, the noise is nearly intolerable and elsewhere direct current from motor generators is employed. The fundamental idea is simple two wires, carefully insulated from each other, are advanced to meet at a point where an arc is formed, immediately in advance of a Jet... 

Some specialized eukaryotic cells have cilia that show a whiplike motion. Sperm cells move with one flagella, which is much longer than a cilium but has a nearly identical internal structure called axoneme. It is composed of nine doublet MTs that form a ring around a pair of single MTs. Numerous proteins bind to the MTs. Ciliary dynein motors generate the force by which MTs slide along each other to cause the bending of the axoneme necessary for motion. 

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