Capacitors power factor improvement

Part IV Power capacitors power factor improvement and system voltage regulation application of shunt and series capacitors... 

Capacitors may be connected across the main busbars of industrial loads in order to provide power factor improvement, but smaller capacitors may also be connected across an individual piece of equipment, as is the case for fluorescent light fittings. 

Figure 2.41 Power factor improvement using capacitors...

Power factor improvement of most industrial loads is achieved by connecting capacitors to either ... 

Power Capacitors Behaviour, Switching Phenomena and Improvement of Power Factor... 

Power capacitors behaviour, switching and improvement of power factor... 

Power capacitors behaviour, switching and improvement of power factor 23/761 Tabfe 23.6 Chari for selection of capacitor rating, to improve the existing p.f. to a higher level... 

Recommended capacitor ratings for direct switching with induction motors, to improve power factor to 0.95 or better at... 

We will notice subsequently that series and shunt compensation are complementary. What a shunt capacitor cannot do, a series capacitor does and vice versa. On a secondary transmission system, say up to 66 kV, a shunt compensation may always be necessary to improve the power factor, as the load would mainly be indtictive. A series compensation may become essential, to improve the stability of the system, to cope with load fluctuations, switching of non-linear loads and voltage fluctuations occurring on the other power system or the grid to which this system may be connected. 

The power factor can be improved with the use of shunt capacitors at the load points or at the receiving end, as discussed above. It is not practical to have a near-fixed loading for all hours of the day. Moreover, there may also be seasonal loads which may upset the parameters considered while installing the capacitor banks. In such conditions the system may therefore have to be underutilized or run under a high risk of instability during... 

The power factor of an installation can be improved by the use of either A.C. synchronous machines or of static capacitor banks. An A.C. synchronous machine will either draw current from the supply or contribute current to the supply, depending on whether the machine is operating ... 

The second method of improving the power factor of an installation is to provide static capacitor banks. These can be installed as a single block at the point of supply busbar, as a set of switchable banks or as individual units connected to specific loads. For an installation where no synchronous machines are installed for other purposes (i.e. as prime movers or generators) then static capacitor banks are almost invariably the most cost-effective way of improving the power factor. 

Arc furnaces are operated in conjunction with large capacitor banks and harmonic filters to improve the power factor and also to filter the harmonic frequency currents so they do not unduly affect other power users sharing the same power fines. It is not uncommon to see arc furnaces supplied from dedicated utility power fines to minimize their impact on other power users. The presence of large capacitance in an electrical system can result in voltage rise due to the leading reactive power demands of the capacitors, unless they are adequately canceled by the lagging reactive power required by the loads. This is why capacitor banks, whether for power factor correction or harmonic current filtration, are switched on when the furnace is brought on line and switched off when the arc furnace is off line. 

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