4 April 2018

Brake Test

  • It is direct test useful to find efficiency of small DC Motor.

Theory

  • The output power of the DC Motor is measured by applying brake to a pulley.
  • One rope is wound round the pulley and its two ends are attached to spring balances W1 and W2

3 April 2018

Compare : Static RAM and Dynamic RAM

Static RAM

  • It can store data as long as the supply is kept on.
  • It consists of flip flop as a memory cells.
  • It is available in both bipolar and MOS technology.
  • It is used where speed is prime consideration

2 April 2018

Reluctance Motor : Construction, Working, Advantages, Disadvantages and Applications

Single Phase unexcited Synchronous Motor

  • The characteristic of single phase unexcited synchronous motor in which excitation does not necessary is given below.
        ( 1 ) It operates on single phase supply. 
        ( 2 ) The stator rotating magnetic field rotates at synchronous speed. 
        ( 3 ) It does not require DC Excitation. 

1 April 2018

Hysteresis Motor : Construction, Working, Advantages, Disadvantages, Characteristics and Applications

Single Phase unexcited Synchronous Motor

  • The characteristic of single phase unexcited synchronous motor in which excitation does not necessary is given below.
       ( 1 ) It operates on single phase supply. 
       ( 2 ) The stator rotating magnetic field rotates at synchronous speed

24 March 2018

Earthing Transformer : Construction, Working and Application

  • It is a special transformer which provides return path for earth fault on Delta connected transformer.

Construction

  • It has primary winding but no secondary winding. 
  • It is a core type transformer consists of three limbs. 
  • Each limb carries two windings which have equal number of turns. 

Tertiary Winding : Construction , Working and Application

  • The three winding transformer as its name suggest consists of three winding : Primary winding, secondary winding and third winding is called as tertiary winding.

Construction

  • The construction of three winding transformer is similar to that of core type transformer. 

Zig zag Transformer : Advantages, Application

  • It is also called as interconnected star connection. The characteristic of zig zag connection is combined characteristics of star and delta connection. 
  • There are six windings in the three cores and each core consists of two winding which has equal number of turns. 
  • Fig A. shows star connection in which each phase consists of two windings. In order to convert this winding into zig – zag connection.