RF2:- Approximate Calculations for Single T/F O/C E/F Relay Settings

     For the power system shown in the picture, HV Bus Voltage is  ?? kV  and LV Bus voltage is ?? Kv.
     T/F capacity is ?? MVA  with percentage short circuit reactance of ?? %.
     T/F HV side CT ratio is ??/1 Amp  and it's LV side CT ratio is ??/1 Amp.
     Calculate HV side and LV side O/C E/F relay settings.

(NOTE: Calculate LV Bus fault current neglecting source impedance. While calculating the O/C E/F TMS; approximately account for source impedance by considering 70% of calculated LV Bus fault current. )

Section-A: Full load and fault current calculations.

1) T/F LV Full Load Current =    Amp.

2) T/F HV Full Load Current =    Amp.

3) T/F LV Bus Short Circuit MVA (Neglecting Source Impedance) =    MVA

Section-B: Decide O/C and E/F Relay PSM

4) T/F LV Relay E/F PSM =   30%    20%    15%

5) T/F HV Relay E/F PSM =   30%    20%    15%

6a) T/F LV Side Relay O/C PSM =   %

6b) T/F HV Side Relay O/C PSM =   %

Section-C: Calculations for O/C and E/F TMS

7a) T/F LV Side fault current for LV Bus Fault =    Amp

7b) T/F HV Side fault current for LV Bus Fault =    Amp

8a) 70% of T/F LV fault current for TMS calculations =    Amp

8b) 70% of T/F HV fault current for TMS calculations =    Amp

9a) LV Relay current for calculation of TMS =    Amp

9b) HV Relay current for calculation of TMS =    Amp

10a) Multiple of current for O/C LV relay =    

10b) Multiple of current for O/C HV relay =    

11a) Time of operation for LV O/C relay with TMS=1 =    Sec.

11b) Time of operation for HV O/C relay with TMS=1 =    Sec.

12a) TMS for O/C LV relay =    

12b) TMS for O/C HV relay =    

13a) Multiple of current for E/F LV relay =    

13b) Multiple of current for E/F HV relay =   

14a) Time of operation for LV E/F relay with TMS=1 =   Sec.

14b) Time of operation for HV E/F relay with TMS=1 =   Sec.

15a) TMS for E/F LV relay =   

15b) TMS for E/F HV relay =   

Topic SETOCTF Ex-2 Your score is:

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