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Element
Range
MOC2C-IEEE
MI / VI / EI
MOC2C-US
CO2 / CO8
[OC2R]
DEF / DEP (*2)
[OC2-2F]
NA / BLK
[OC3EN]
Off / On
[OC3-2F]
NA / BLK
[OC4EN]
Off / On
[OC4-2F]
NA / BLK
[EF1EN]
Off / On
[MEF1]
DT/IEC/IEEE/US/CON
[MEF1C]
MEF1C-IEC
NI / VI / EI / LTI
MEF1C-IEEE
MI / VI / EI
MEF1C-US
CO2 / CO8
[EF1R]
DEF / DEP (*2)
[EF1-2F]
NA / BLK
[EF2EN]
Off / On
[MEF2]
DT/IEC/IEEE/US/CON
[MEF2C]
MEF2C-IEC
NI / VI / EI / LTI
MEF2C-IEEE
MI / VI / EI
MEF2C-US
CO2 / CO8
[EF2R]
DEF / DEP (*2)
[EF2-2F]
NA / BLK
[EF3EN]
Off / On
[EF3-2F]
NA / BLK
[EF4EN]
Off / On
[EF4-2F]
NA / BLK
(*1) Current values shown in the parenthesis are in the case of a 1 A rating. Other current values are in
the case of a 5 A rating.
(*2) DEF: Instant or Definite time, DEP: Inverse time
(1) Settings for Inverse Time Overcurrent Protection
Current setting
In Figure 2.1.17, the current setting at terminal A is set lower than the minimum fault current in the
event of a fault at remote end F1. Furthermore, when also considering backup protection for a fault
on the next feeder section, it is set lower than the minimum fault current in the event of a fault at
remote end F3.
To calculate the minimum fault current, phase-to-phase faults are assumed for the phase
overcurrent element, and phase to earth faults for residual overcurrent element, assuming the
probable maximum source impedance. When considering the fault at F3, the remote end of the
next section is assumed to be open.
The higher the current setting, the more effective the inverse characteristic. On the other hand, the
lower the setting, the more dependable the operation. The setting is normally 1 to 1.5 times or less
Step
Default
Remarks
MI
Required if [MOC2] = IEEE.
CO2
Required if [MOC2] = US.
DEF
OC2I reset characteristic. Required if
[MOC2] = IEEE, US or CON.
NA
Blocked by ICD
Off
OC3 Enable
NA
Blocked by ICD
Off
OC4 Enable
NA
Blocked by ICD
Off
EF1 Enable
DT
EF1 characteristic
EF1I inverse curve type.
NI
Required if [MEF1] = IEC.
MI
Required if [MEF1] = IEEE.
CO2
Required if [MEF1] = US.
DEF
EF1I reset characteristic. Required if [MEF1]
= IEEE, US or CON.
NA
Blocked by ICD
Off
EF2 Enable
DT
EF2 characteristic
EF2I inverse curve type.
NI
Required if [MEF2] = IEC.
MI
Required if [MEF2] = IEEE.
CO2
Required if [MEF2] = US.
DEF
EF2I reset characteristic. Required if [MEF2]
= IEEE, US or CON.
NA
Blocked by ICD
Off
EF3 Enable
NA
Blocked by ICD
Off
EF4 Enable
NA
Blocked by ICD
⎯
⎯
25
6 F 2 S 0 8 4 2
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