Q1.) Proper relay Co-ordination ensures-
Selective tripping of faulty element
Fast clearing of the fault
Overlapping of protection zones
All of above
Q2.) While calculating over current relay settings for line fault current considered as-
Contribution by respective line for remote bus fault
Total fault current for remote bus fault
Fault immediately after relaying point
None of this
Q3.) As per IEC-60255 Which are the four names of relay operational characteristics-
Normal Inverse, Extremely Inverse, Very Inverse and Longtime Inverse
Longtime Inverse, Extremely Inverse, Very Inverse and IDMT
Very Inverse, Longtime Inverse, Extremely Inverse and Standard Inverse
Standard Inverse, Normal Inverse, Very Inverse and Extremely Inverse
Q4.) For IEC-60255 SI Curve Time of Operation for the relay is given by the equation-
0.14/Ix^0.02 - 1
(0.14/Ix^0.02) - 1
0.14/(Ix^0.02 - 1)
13.5/(Ix - 1)
Q5.) For a overcurrent relay of 5 amp; rely time of operation is given by K/(Ix^a - 1) here Ix represents-
CT secondary current during fault
CT primary current during fault
(CT Secondary Current)/(RelayPSM)
(CT Secondary Current)/(Relay Pickup Current)
Q6.) While carrying out testing of a 1 A overcurrent relay its PSM is kept at 50% and TMS is kept at 100%. For injected current of 1 A, 1.5 A, 2 A, 5 A, and 10 A its time of operation would be-
2 sec, 5 sec, 10 sec, 20 sec, 100 sec respectively
10 sec, 5 sec, 3 sec, 2 sec, 1 sec respectively
10 sec, 5.7 sec, 4.5 sec, 3 sec, 2.2 sec respectively
10 sec, 6.3 sec, 5 sec, 3 sec, 2.2 sec respectively
Q7.) For a 132kV line having 0.2 Panther conductor and CT ratio is 400/1 A; PSM setting for overcurrent relay would be-
130% without load trimming and alarm
140% without load trimming and alarm
130% with alarm only
140% with load trimming only
Q8.) TMS of earth fault relay as compared with overcurrent relay for same location is-
50% more
30% more
More
None of this
Q9.) For Earth Fault relay PSM shall be-
30%
20%
10%
20%-30% but depends on CT ratio and full load current of the equipment being protected
Q10.) For a 132kV line with CT ratio of 800/1, overcurrent PSM 75%, contributing fault current of 1600 A for remote bus fault, to have relay operation time of 500 ms TMS shall be-
0.05
0.07
0.10
0.115
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