Capacitor motor

Capacitor Motor. A capacitor motor is a single-phase induction motor with a main winding arranged for a direct connection to a source of power and an auxiliary winding connected in series with a capacitor. There are three types of capacitor motors, as follows ... 

Capacitor-start motor. A capacitor-start motor is a capacitor motor in which the capacitor phase is in the circuit only during the starting period. 

Permanent-split capacitor motor. A permanent-split capacitor motor is a capacitor motor having the same value of capacitance for both starting and running conditions. 

Starting Capacitance for a Capacitor Motor. The starting capacitance for a capacitor motor is the total effective capacitance in series with the starting winding under locked-rotor conditions. 

The Super Shaker, manufactured by A. Gallenkamp and Co. Ltd., is excellent, t For example, a capacitor motor, 1.425 rp.rn., supplied by British Thomson Houston Co. Ltd., Rugby, England. 

Two-Value-Capacitor Motors. Two-value-capacitor motors have both a switched-start capacitor and a run capacitor to improve full-load current, starting torque, and power factor (Fig. 5.106). Both are connected in parallel to the start winding, with the start capacitor disconnecting as the motor accelerates.These motors provide good overall torque characteristics and are quiet-running. 

FIGURE 5.105 Schematic and speed vs. torque diagram—ac permanent split-capacitor motor. 

Cyanohydrins are used primarily as intermediates in the production of other chemicals. Manufacture of methyl methacrylate, used to make acrylic mol ding resins and clear sheet, eg, Plexiglas acrylic sheet, from acetone cyanohydrin is the most economically important cyanohydrin process (see Methacrylic polymers). Cyanohydrins are also used as solvents in appHcations including fiber-spinning and metals refining. Cyanohydrins and derivatives reportedly act as antiknock agents in fuel oil and motor fuels and serve as electrolytes in electrolytic capacitors. 

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. 

The size of capacitors C, C l or C will depend upon the horsepower of the motor and the torque requirement of the load. For starting duty capacitors generally in the range of 30-100 pF and for a run of 2-20 //F will be adequate. 

Whenever frequent swilehings are likely, high transient voltages may develop and harm the motor windings and the capacitors. Fast discharge facilities must be provided across the capacitor terminals to damp such transients quickly. Sec Section 25.7. for more details on discharge devices. 

Note If a power capacitor is connected after the relay, say across the motor terminals, to improve the p.f. of the machine, then only the corrected value of the current musi be used. For example, if a capacitor bank of 130 kVAr is used for an individual correction of the machine then... 

Such as motors (not really but can be considered so being balanced loads) heating loads, capacitor and incandescent lighting loads etc. Of the linear loads, the following will require special consideration. 

All electrical equipment are designed for a specific BIL, as indicated in Tables 11.6, 13.2, 14.1, and 32.1(A) for motors, switchgears and bus systems respectively, and Tables 13.2 and 13.3 for the main power system (line clearances and insulators). If the actual severity of a prospective surge, i.e. its amplitude and/or rise time or both, is expected to be higher than these levels (higher amplitude and lower rise time) the same must be damped to a safe level, with the use of surge arresters, surge capacitors or both as discussed later. 

A surge capacitor offers a near-open circuit during normal operation (at or near the power frequencies) and a near-short-circuit to the arriving surges at surge frequencies, while the inductance of the motor windings (<> will... 

To illustrate the above, consider a surge capacitor of 0.25 // F being used in parallel with a 350 kW, 6.6 kV motor. If the likely FOW is presumed to have an amplitude up to 5 p.u., then the energy this capacitor can absorb... 

With this particular arrester, the motor has to be specially designed for the higher level of FOW impulse voltage withstand. But the manufacturer can always modify the protective characteristics of the arrester, depending upon the system s requirements. The matter may therefore be referred to the manufacturer for recommendations. The arrester may be fitted with a 0.25, uF surge capacitor in parallel, to reduce the steepness of the FOW (for the arrester of example 17.5, it is 14/0.2 kV/jUS) to a safer value. 

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