Rf-5: Backup Relay Setting Calculations for ICTs in Grid.

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     At a 220/132kV Sub-Station there are two ICTs operating in parallel. ICT-I having capacity of 200 MVA. Whereas the capacity of ICT-II is 100 MVA.

     ICT-I HV Side CT Ratio is ??/1 Amp.  while it's IV Side CT Ratio is ??/1 Amp.

     ICT-2 HV Side CT Ratio is ??/1 Amp.  while it's IV Side CT Ratio is ??/1 Amp.



     HV and IV Bus fault levels and contribution of fault current by each ICT for HV and IV bus fault is as shown in the following table

     Calculate HV side and IV side **FOR ICT-I** backup relay setting for IDMT and HS element.

Bus Fault Levels MVA
Bus	Fault Type	Fault Level in MVA
ICT HV Bus	3-Phase (LLL)	??
	1-Phase (SLG)	??
ICT IV Bus	3-Phase (LLL)	??
	1-Phase (SLG)	??

Fault Current contribution by ICTs
Fault At	Type	ICT	Winding	Ampere
ICT HV Bus Fault	3-Phase (LLL)	ICT-I	HV Winding	??
			IV Winding	??
		ICT-II	HV Winding	??
			IV Winding	??
	1-Phase (SLG)	ICT-I	HV Winding	??
			IV Winding	??
		ICT-II	HV Winding	??
			IV Winding	??
ICT IV Bus Fault	3-Phase (LLL)	ICT-I	HV Winding	??
			IV Winding	??
		ICT-II	HV Winding	??
			IV Winding	??
	1-Phase (SLG)	ICT-I	HV Winding	??
			IV Winding	??
		ICT-II	HV Winding	??
			IV Winding	??

Section-A: Decide PSM for HV and IV side O/C and E/F Relays.

1.a) HV O/C PSM =    %

1.b) HV E/F PSM =    %

2.a) IV O/C PSM =    %

2.b) IV E/F PSM =    %

Section-B.1: TMS calculations for HV O/C and E/F Relay.

3.a) ICT-I fault current for calculations of HV O/C Relay Settings =    Amp

3.b) HV O/C Relay Current for above fault =    Amp.

3.c) HV O/C Relay Current Multiple =    xIset

4.a) HV O/C Relay Time of Operation with TMS=1 =    Sec.

4.b) TMS to have Time of operation 500ms =    

5.a) ICT-I fault current for calculations of HV E/F Relay Settings =    Amp.

5.b) HV E/F Relay Current for above fault =    Amp.

5.c) HV E/F Relay Current Multiple =    xIset

6.a) HV E/F Relay Time of Operation with TMS=1 =    Sec

6.b) TMS to have Time of operation 500ms   

Section-B.2: HS Calculations for HV O/C and E/F.

Toolbox (Set focus on any text box and Press enter key to recalculate)
Multiple of Current =  xIn      Operation Time with TMS 1 = 000.000 Sec.

---

    +         =     000.000              -         =     000.000
    *         =     000.000              /         =     000.000

7.a) ICT-1 HV CT Current for IV Bus LLL Fault =    Amp.

7.b) ICT-1 HV CT Current for HV LA LLL Fault =    Amp.

7.c) ICT-1 HV CTR =    /1 Amp.

8.a) O/C HV Relay Current for calculations of HS1 =    Amp.

8.b) O/C HV Relay Current for calculations of HS2 =    Amp.

9.a) E/F HV Relay Current for calculations of HS1 =    Amp.

9.b) E/F HV Relay Current for calculations of HS2 =    Amp.

10) HV Relay O/C HS1 Setting =    xIn

11) HV Relay O/C HS2 Setting =    xIn

12) HV Relay E/F HS1 Setting =    xIn

13) HV Relay E/F HS2 Setting =    xIn

Section-C.1: TMS calculations for IV O/C and E/F Relay.

14.a) ICT-I fault current for calculations of IV O/C Relay Settings =    Amp.

14.b) IV O/C Relay Current for above fault =    Amp.

14.c) IV O/C Relay Current Multiple =    xIset

15.a) HV O/C Relay Time of Operation with TMS=1 =    Sec.

15.b) TMS to have Time of operation 500ms =    

16.a) ICT-I fault current for calculations of IV E/F Relay Settings =    Amp.

16.b) IV E/F Relay Current for above fault =    Amp.

16.c) IV E/F Relay Current Multiple =    xIset

17.a) HV E/F Relay Time of Operation with TMS=1 =    Sec.

17.b) TMS to have Time of operation 500ms   

Section-C.2: HS Calculations for IV O/C and E/F.

18.a) ICT-1 IV CT Current for HV Bus LLL Fault =    Amp.

18.b) ICT-1 IV CT Current for IV LA LLL Fault =    Amp.

18.c) ICT-1 IV CTR =    /1 Amp.

19.a) O/C HV Relay Current for calculations of HS1 =    Amp.

19.b) O/C HV Relay Current for calculations of HS2 =    Amp.

20.a) E/F HV Relay Current for calculations of HS1 =    Amp.

20.b) E/F HV Relay Current for calculations of HS2 =    Amp.

21) IV Relay O/C HS1 Setting =    xIn.

22) IV Relay O/C HS2 Setting =    xIn.

23) IV Relay E/F HS1 Setting =    xIn.

24) IV Relay E/F HS2 Setting =    xIn.

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