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Name of Feeder
Load Current: (IL) 384 Amp
Min Fault Current ( Line-Line): 11000 Amp
Max Fault Current ( Line-Line): 22000 Amp
Relay Type
Relay Code
Relay No
CT Primary Current 600 Amp
CT Secondary Current 1 Amp
Relay Error (%) 7.5%
CT Error (%) 10.0%
Over shoot 0.05 Sec
C.B Interrupting Time 0.17 Sec
Safety 0.33 Sec
Total Grading Time 0.58 Sec
Expected Operating Time of Relay 0.271 Sec
Low Over Current Setting: (I>)
Over Load Current : 125% X IL
Over Load Current :(In) 480 Amp
Required Over Current Relay Plug Setting 0.8 0.8 A X In
Actual Plug Setting of Over Current Relay 0.80 0.8 A X In
Time Dial Setting of Over Current Relay (TMS) 0.125 Sec
Curve Selection for Relay Normal Inverse (NI)
Pick Up Setting of Over Current Relay (PMS): (I>) 0.8 Amp
Plug Setting Multiplier (PSM): 22.92
Operation Time of Relay 2.17 Sec
Actual Operating Time of Relay : (tI>) 0.271 Sec
Total Grading Time 0.58 Sec
Operating Time of Previous Up steam Relay 0.85 Sec
High Over Current Setting: (I>>)
Actual Plug Setting of Relay 2.50 2.5 A X In
Time Dial Setting of Over Load Relay (TMS) 0.100 Sec
Curve Selection for Relay Normal Inverse (NI)
Pick UP Setting of Over Load Relay (PMS): (I>>) 2.5 Amp
Plug Setting Multiplier (PSM): 7.33
Time of Operation of Relay 3.44 Sec
Actual Operating Time of Relay : (tI>>) 0.34 Sec
Total Grading Time 0.58 Sec
Operating Time of Previous Up steam Relay 0.92 Sec
Pick Up Setting of Over Current Relay (PMS): (I>) OK
Low Over Current Setting: (I>) 0.8 A X In Amp
Actual Operating Time of Relay(tI>) 0.271 Sec
High Over Current Setting: (I>>) 2.5 A X In Amp
Actual Operating Time of Relay(tI>>) 0.34 Sec
Summary of Over Current Relay Setting:
Over Current Relay Setting
Calculation of IDMT Over Current Relay Settings(50/51):
Name of Feeder
Load Current: (IL) 384 Amp
Min Fault Current ( Line-Ground): 11000 Amp
Max Fault Current ( Line-Ground): 22000 Amp
Relay Type
Relay Code
Relay No
CT Primary Current 600 Amp
CT Secondary Current 1 Amp
Relay Error (%) 7.5%
CT Error (%) 10.0%
Over shoot 0.05 Sec
C.B Interrupting Time 0.17 Sec
Safety 0.33 Sec
Total Grading Time 0.58 Sec Enter Data in White Background Cells
Expected Operating Time of Relay 0.176 Sec
Low Earth Fault Setting: (Ie>)
Earth Fault Current : 20% X In
Earth Fault Current 96 Amp
Required Earth Fault Relay Plug Setting 0.2 0.2 A X In
Actual Plug Setting of Earth Fault Relay 0.16 0.2 A X In
Time Dial Setting of Earth Fault Relay (TMS) 0.125 Sec
Curve Selection for Relay Normal Inverse (NI)
Pick Up Setting of Earth Fault Relay (PMS): (Ie>) 0.16 Amp
Plug Setting Multiplier (PSM): 114.58
Operation Time of Relay 1.41 Sec
Actual Operating Time of Relay : (te>) 0.18 Sec
Total Grading Time 0.58 Sec
Operating Time of Previous Up steam Relay 0.76 Sec
High Earth Fault Setting: (Ie>>)
Actual Plug Setting of Relay 2.50 2.5 A X In
Time Dial Setting of Over Load Relay (TMS) 0.100 Sec
Curve Selection for Relay Normal Inverse (NI)
Pick UP Setting of Earth Fault Relay (PMS): (Ie>>) 2.5 Amp
Plug Setting Multiplier (PSM): 7.33
Time of Operation of Relay 3.44 Sec
Actual Operating Time of Relay : (te>>) 0.34 Sec
Total Grading Time 0.58 Sec
Operating Time of Previous Up steam Relay 0.92 Sec
Pick Up Setting of Over Current Relay (PMS): (I>) OK
Low Earth Fault Setting: (Ie>) 0.2 A X In Amp
Actual Operating Time of Relay(te>) 0.176 Sec
High Earth Fault Setting: (Ie>>) 2.5 A X In Amp
Actual Operating Time of Relay(te>>) 0.34 Sec
Summary of Earth Fault Relay Setting:
Jignesh.Parmar
www.electricalnotes.wordpress.com
Earth Fault Relay Setting
Calculation of IDMT Earth Fault Relay Settings(50N/51N):
Normal Inverse (NI)
Very Inverse (VI)
Exteremely Inverse (EI)
Long Time Inverse
Enter Data in White Background Cells
Jignesh.Parmar
www.electricalnotes.wordpress.com
