141 145

 141. What is electric traction? 

Traction means using the electric power for traction system i.e. for railways, trams,  trolleys etc. 

Electrical traction means use of the electricity for all these. Now a days, magnetic  traction is also used for bullet trains. 

Basically dc motors are used for electric traction systems. 

143. How can you start-up the 40w tube lite with 230v AC/DC without using any choke/Coil? 

It’s possible by means of Electronic choke. Otherwise it’s not possible to ionize the  particles in tube. Light, with normal voltage. 

144. What is “pu” in electrical engineering? 

Pu stands for per unit and this will be used in power system single line diagram there it is  like a huge electrical circuit with no of components (generators, transformers, loads) with 

different ratings (in MVA and KV). 

To bring all the ratings into common platform we use pu  concept in which, in general largest MVA and KV ratings of the component is considered as base 

values, then all other component ratings will get back into this basis. Those values are called as pu values. (p.u=actual value/base value).

145. Operation carried out in Thermal power station?

The water is obtained in the boiler and the coal is burnt so that steam is obtained this  steam is allowed to hit the turbine, the turbine which is coupled with the generator generates the  electricity.