How many types of colling system it transformers?

Electrical and Electronic Engineering - Interview Questions

* ONAN (oil natural,air natural)
* ONAF (oil natural,air forced)
* OFAF (oil forced,air forced)
* ODWF (oil direct,water forced)
* OFAN (oil forced,air forced)

Recently Updated Interview Questions in Electrical and Electronic Engineering

What are the advantages of VSCF wind electrical system?

Advantages of VSCF wind electrical system are :

* No complex pitch changing mechanism is needed.
* Aero turbine always keeps going at maximum efficiency point.
* Extra energy in the high wind speed region of the speed – duration curve can be extracted
* Significant reduction in aerodynamic stresses, which are associated with constant – speed operation.

Why electricity in India is in the multiples of 11 like 11kv, 22kv, 33kv?

Transformer Induced voltage equation contains 4.44 factor.

E=4.44*f*T*phi
E -Induced emf per phase
T -number of turns
f -frequency
phi -maximum flux per pole
From the equation we see that E is proportional to 4.4 and it is in turn multiple of 11.

So always transmission voltage is multiple of 11