Power capacitors

The dielectric materials used in power capacitors include paper, polypropylene, and mixed vacuums impregnated with mineral or synthetic oil. The most reliable dielectric material is polypropylene. The metal electrodes can be aluminum foils or thin metal films deposited onto the surfaces of the dielectrics. The reliabilities and lifetimes of power capacitors are always concerns because of the possibility of overheating. 

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Power capacitors are installed to compensate for the reactive power, particularly that which the machine draws from the grid. The capacitors must be suitable for a minimum voltage of + 13% (generally V, + 15%). 

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... 

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

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

Tliis is the prime cause of noise and distortion in an audio system. The capacitive coupling (conduction) between the power and the communication lines gives rise to such an effect. It is associated more with the voltage of the system and particularly when it is capacitor compensated. Even without the power capacitors, the leakage (coupling) capacitances between the HV or EHV power lines, particularly 132 kV and above, and the overhead communication lines play an important role and give rise to this phenomenon. Systems lower than 132 kV do not cause such a situation as a result of the insignificant capacitive effect. 

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... 

Shunt power capacitors of the self healing type for a.c. systems having rated voltage up to and including 1000 V 13340/1993 BS EN 608.31 -1/1998... 

Shunt power capacitors of non self-healing types up to and including 1000 V General performance, testing and rating. Safety requirements. Guide for installation and operation 13585-1/1994 BS EN 60931-1/1996... 

Reliability of shunt or series power capacitors is of utmost importance for the security of the system on which they are installed. Their failure may disturb the system or result in a system outage. 

Ceniral Board oi Irrigation and Power. India. Manual on Shtint Power Capacitors - Operation and Maintenance. Technical Report No. 33. Jan. (1984). 

Longlnnd. T.. Hunt. T.W. and Brecknell. W.A.. Power Capacitor Handbook, Bulterworth. London (1984). 

Protection, maintenance and testing of capacitor units 26/839 Table 26.3 Power frequency lest voltages and their duration for voltage tests on a power capacitor unit or bank... 

Table 26.4 Insulation levels for power capacitor units...

AIEE Conimiltee. Repot of a Survey on the Connection of Shunt Ciipocitor Banks. Report Vol. 77. pp. )4.S2-,S8, Feb. (I9.s9). Central Board of Irrigation and Power. India. Manual on Shioii Power Capacitors - Operation and Mainiena/u e. Technical Rept>n No. 33. Jan, (1984). 

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