Application of Dc Generators

Application of dc generators.

Separately excited generators are used in Ward Leonard systems of speed control, because self excitation would be unstable at lower voltages.

Series wound generators are used for series arc lighting, series incandescent lighting, as series boosters for increasing the voltage across the feeder carrying current furnished by some other source and for a few special purposes, such as for supplying the field current for regenerative braking of de locomotives.S

Shunt wound generators with field regulators are used for light and power supply purposes and also used for charging of batteries.

Compound wound (over compounded type) generators are generally used for lighting and power services.

Differential compounded generators are used as arc welding generators.

Note: With the advent of various power electronic devices, there is no doubt that the importance of de generators has gone down. At present time bulk of power is generated in the form of alternating current because of technical and economical reasons.

Hence the use of dc generators is very limited. They find application mainly in supplying excitation to the small and medium size alternators. For industrial applications of direct current like electrolytic processes, welding processes and variable speed motor drives, the present trend is to generate ac and then convert it into dc by converters.

For conversion of ac into do the dc generator, as a part of motor (ac) a m generator (dc) set, has to compete the SCR rectifiers and various other controlled power devices which usually are cheaper in cost, compact -ve in size, relatively noise-free in operation and require minimum maintenance, though they suffer from the disadvantages of having poor power factor, harmonic generation, poor braking etc.

However, some of the important applications of dc generators include dynamometers, welding, cross-field generators, for closed-loop control systems, tacho generators (not covered in this book) etc.

Separately excited dc generators still find use for a wide output voltage control such as in Ward-Leonard system of speed control.