Eng.Mohamed Hosny Mahfouz

In generating station electrical power is generated at medium voltage level that ranges from 11 kV to 25 kV. This generated power is sent to the generating step up transformer to make the voltage level higher. From this point to the user end voltage level varies in different levels. We can realize this voltage level variation step by step. At 11 kV or more than that up to 25 kV voltage level is maintained at alternator stator terminals to generate electrical power in the generating station. This generated power is fed to the generating step up transformer to make this medium voltage level to higher level, i.e. up to 33 kV. Power at 33 kV is sent to the generating substation. There the transformer increases the voltage level to 66 kV or 132 kV. From this generating substation power is sent to the nearer substation to increase the voltage level higher than previous. This level of voltage is increased at different suitable levels, it may be at 400 kV or 765 kV or 1000 kV. Th

A universal motor is a special type of motor which is designed to run on either DC or single phase AC supply. These motors are generally series wound (armature and field winding are in series), and hence produce high starting torque (See characteristics of DC motors here). That is why, universal motors generally comes built into the device they are meant to drive. Most of the universal motors are designed to  operate at higher speeds, exceeding 3500 RPM. They run at lower speed on AC supply than they run on DC supply of same voltage, due to the reactance voltage drop which is present in AC and not in DC. There are two basic types of universal motor :  (i)compensated type and (ii) uncompensated type Construction of Universal motor Construction of a universal motor is very similar to the construction of a DC machine . It consists of a stator on which field poles are mounted. Field coils are wound on the field poles. However, the whole magnetic path (stato