Physics Education

Distribution System That part of power system which distributes electric power for local use is known as distribution system. Freeders . A feeder is a conductor which connects the substation (or localized generating station) to the area where power is to be distributed. Generally, no tappings are taken from the feeder so that current in it remains the same throughout. Distributors. A distributor is a conductor from which tappings are taken for supply to the consumers. In Fig. AB, BC CD and DA are the distributors. The current through distributor is not constant because tappings are taken out.   Service mains. A service mains is generally a small cable which connects the distributor to the consumers' terminals. Classification of Distribution Systems A distribution system may be classified according to: (i) Nature of current. According to nature of current, distribution systems may be classified as (a) d.c. distributio...

Comparison of D.C. and A.C. Transmission The electric power can be transmitted either by means of dc or ac. Each system has its own merits and demerits. 1. D.C. transmission. For some years past, the transmission of electric power by dc, has been receiving the active consideration of engineers due to its numerous advantages. Advantages (i)     It requires only two conductors as compared to three for a.c. transmission. (ii)    There is no inductance, capacitance, phase displacement and surge problems. (iii)   Due to the absence of inductance, the voltage drop in a d.c. transmission line is less. For this reason, a d.c. transmission line has better voltage regulation. (iv) There is no skin effect in a d.c. system. Therefore, entire cross-section of the conductor is utilized. (v)   For the same working voltage d.c. line requires less insulation. (vi) A dc, line has less corona loss and reduced interference with communication. (vii) In d.c. tran...