Rf2 - Identification of currents for calculations of ICT backup relay IDMT settings

OcEf Calc Grid ICT
     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.



     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

     Identify currents **FOR ICT-** backup relay setting for IDMT 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


(NOTE: Go through the table data and enter your answers. )
1) Current corresponding to HV side IDMT O/C Relay settings =    Amp.
2) Current corresponding to HV side IDMT E/F Relay settings =    Amp.
3) Current corresponding to IV side IDMT O/C Relay settings =    Amp.
4) Current corresponding to IV side IDMT E/F Relay settings =    Amp.
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