Rf4 - Reverse Engineering check the validity of LTS scheme

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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.
     Alarm and LTS scheme provided for ICT-I using HV side CT; alarm and LTS are at 100% and 105% respectively of ICT full-load current.
     LTS scheme operational time delay is 2 second with load cut-off for 150 MVA;

     If both ICTs operating at full load and after tripping of 100 MVA ICT let load on 200 MVA ICT HV side is ?? Amp. Then-
     WHETHER LTS SCHEME FOR ICT-I WILL OPERATE SUCCESSFULLY?.
     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

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	??

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Multiple of Current =  xIn      Operation Time with TMS 1 = 000.000 Sec.

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

Section-A: Calculation of HV O/C PSM and TMS.

1) HV Side allowable current for ICT-I =    Amp.

2) ICT-I HV Side O/C PSM =    %

3.a) Current for calculations of ICT-I HV Side O/C TMS =    Amp.

3.b) Corresponding HV Side O/C Relay Current =    Amp.

3.c) ICT-I HV Side O/C Relay Current as multiple of set value =    xIset

4.a) Time of operation for ICT-I HV O/C Relay with TMS=1 =    Sec.

4.b) TMS to have operational time as 500 ms =    

Section-B: Calculation time of operation for O/C Relay when ICT-II Trips.

5.a) ICT-I HV Side current when ICT-II trips =    Amp.

5.b) Corresponding HV Side O/C Relay Current =    Amp.

5.c) ICT-I HV Side O/C Relay Current as multiple of set value =    xIset

6.a) ICT-I HV O/C Operation time when ICT-II trips with TMS 1   Sec.

6.b) Time of operation for ITC-I HV O/C relay with adopted TMS =    Unit

7) Whether ICT-I LTS Scheme will operate successfully?
YES    UNCERTAIN    NO

Topic SETICTBU Ex-4 Your score is:

000

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ABD AMT NSK PUN NGP KRD VSH

ABD1 ABD2 JALN PRBN NND1 NND2 LTR1 LTR2 BEED PRLI EKTN GRWL WALJ TPTN KMBH