Rf-4: - O/C E/F Settings Calculations for Radial Double Circuit Line.

       132kV Double Circuit 0.2 ACSR line A-B is 30km long and feeding radially to Bus-B. End A CT Ratio is ??/1 Amp. And end B CT Ratio is ????/1 Amp.
       Bus-A 3-Ph short circuit level is ???? MVA. and Bus-B 3-Ph short circuit level is  ???? MVA.
       A) Calculate the Overcurrent relay settings  of relay X at Bus-A and relay Y at Bus-B for time of operation as 500 ms and 300 ms respectively; considering fault at q (on the line very near to Bus-B).


INSIGHT:
       B) Let there be a fault on the line at p; at a distance of 20% from Bus-A. Calculate the fault current for relay Z and relay Y. What would be the time of operation for relay Z (Settings of relay Z are same as X). Whether relay Y will pickup? And if so what would be it's time of operation.
       C) For fault mentioned in B and after opening of CB at Z (Bus-A); what will be operation time for the relay at X and Y. Neglect initial time up to opening of CB at Bus-A.
(NOTE: For fault MVA calculations use base MVA as 100. For 0.2 ACSR line X1 = 0.4 ohms/km

Section-A: Calculations considering fault at q.

1) Relay X - Overcurrent PSM (Roundup to 5%) =    %

2) Relay X - 3-ph fault current for fault at q =    Amp

3) Relay X - 3-ph fault current as multiple of PSM =   X

4a) Relay X - Time of operation for O/C relay with TMS 1 =   sec

4b) Relay X - To have time of operation as 500 ms TMS =   sec

5) Relay Y - Overcurrent PSM (Roundup to 5%) =    %

6) Relay Y - 3-ph fault current for fault at q =   Amp

7) Relay Y - 3-ph fault current as multiple of PSM =   X.

8a) Relay Y - Time of operation for O/C relay with TMS 1 =   sec

8b) Relay Y - To have time of operation as 300 ms TMS =   

Section-B: Calculations considering fault at p;
on the line at 20% distance from source end.

9) +Ve sequence source reactance for Bus-A =   %

9.1) +Ve sequence reactance from Bus-A to fault point p(20% of line) =   %

9.2) +Ve sequence reactance from Bus-A to fault point p 180% of the line.
Section-> Bus-A-Bus-B-q-p =      %

9.3a) +Ve sequence equivalent reactance from source to fault point p =   %
9.3b) Fault MVA for fault at p =   MVA
9.3c) Fault Current for fault at p =   Amp

10a) Relay Z current for the fault at p =   Amp

10b) Relay Y current for the fault at p =   Amp

11) Whether relay at Y pickup? =   YES    NO   

12a) Relay Z - Time of Operation =   miliseconds

12b) Relay Y - Time of Operation =   miliseconds

Section-C: Calculations after opening of CB by Z.

After opening CB by Z
13a) +Ve sequence equivalent reactance from source to fault point p =   %
13b) Fault MVA for fault at p =   MVA
13c) Fault Current for fault at p =   Amp

14a) Relay-Y current =   Amp

14b) Relay-X current =   Amp

15a) Relay-Y time of operation in miliseconds =   miliseconds

15b) Relay-X time of operation in miliseconds =   miliseconds

Topic SETOCLN Ex-4 Your score is:

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