PROTECTION AND SWITCHGEAR expected university questions

EE2402 PROTECTION AND SWITCHGEAR

IMPORTANT QUESTIONS

 

1. Describe essential qualities of protective relaying system
2. (i) Explain Peterson coil / Arc-suppression coil of neutral earthing with neat diagram  and state its merits and demerits.(8)

(ii) Explain the various protective schemes used in power system. How the protective zones are decided for complete protection of power system.(8)

3.      (i) Explain the method of calculating fault current using symmetrical Components.(8)

(ii) Explain the operation of surge absorbers and surge diverters. (8)

4.      Discuss the procedure for computation of fault currents in power system when a L-L-G fault occurs?

5.      Explain the working principle of non-directional & directional induction type over current relay and explain the operating characteristics.

6.      Explain differential relay and its types with neat diagrams. Also discuss its applications. 

7.      Explain the clearly the difference between Impedance, Reactance & MHO relay. Give the torque equation of each type & show their characteristics on R-X  diagram.

8.      (i) Explain the different types of electromagnetic relays in detail.(10)

(ii) List the various building blocks that constitute for static relay & give brief description about  

     each block.   (6)   

9.      Draw Merz Price circulating current protection scheme for protection of alternator against stator faults and explain its operation. Explain why 100% of winding of alternator cannot be protected using this method. Explain the modified protection scheme to provide greater sensitivity in the event of earth fault on the stator winding.          

10.  (i) Explain the operation of buchholz relay with neat diagram.(8)

(ii) Differentiate CT & PT. (8)

11.  (i) Discuss how the generator is protected against an interturn fault with necessary diagram. (6)

(ii) Explain protection scheme used in star/star & star/delta transformers against through fault &  

      internal fault for grounded & ungrounded conditions. (10)

12.  Explain various methods used for busbar protection.       

13.  (i) Explain the current chopping in C.B &how it can be minimized.   

(ii) Discuss about resistance switching of CB.                                              

14.  (i) Explain the arc interruption methods used in circuit breakers.      

(ii) Explain the term restriking voltage.  Derive an expression for the   same in terms of system voltage,Inductance and capacitance across a CB contact when a three phase fault occurs.        

15.  Explain AC and DC circuit breaking.

16.  Give the constructional View of SF6 CB and explain its principle of working and types.

17.  Explain the types of Oil Circuit breakers with neat sketch.

18.   (i) Compare Different types of Circuit Breakers in detail       (8)

(ii) Write short notes on testing of C.B.            (8)