5-280 L90 Line Current Differential System GE Multilin5.7 CONTROL ELEMENTS 5 SETTINGS5To distinguish between single-phase disappearance and system disturbance in all three phases (such as load change,switching, etc.), the broken conductor element monitors the change in all three phase currents at the present instance andat four cycles previous. It also monitors changes in the I_2 / I_1 ratio, I_1 minimum, and I_1 maximum.The broken conductor function should not be used to respond to fault transients and single-pole tripping/reclosing condi-tions. Therefore, the time delay should be programmed to a sufficient length to ensure coordination with the breaker deadtime of the recloser function.• BROKEN CONDUCTOR 1 FUNCTION: This setting enables and disables the broken conductor function.• BROKEN CONDUCTOR 1 SOURCE: This setting selects a signal source used to provide three-phase current inputsto this function.• BROKEN CONDUCTOR 1 I2/I1 RATIO: This setting specifies the ratio of negative-sequence current to positive-sequence current. When one phase conductor is broken, the I_2 / I_1 ratio with a balanced remaining two phases is50%. So normally this setting should be set below 50% (for example, to 30%).• BROKEN CONDUCTOR 1 I1 MIN: This setting specifies the minimum positive-sequence current supervision level.Ensure this setting is programmed to a sufficient level to prevent I_2 / I_1 from erratic pickup due to a low I_1 signal.However, this setting should not be set too high, since the broken conductor condition cannot be detected under lightload conditions when I_1 is less than the value specified by this setting.• BROKEN CONDUCTOR 1 I1 MAX: This setting specifies the maximum I_1 level allowed for the broken conductorfunction to operate. When I_1 exceeds this setting, this it is considered a fault. This broken conductor function shouldnot respond to any fault conditions, so normally this setting is programmed to less than the maximum load current.• BROKEN CONDUCTOR 1 PKP DELAY: This setting specifies the pickup time delay for this function to operate afterassertion of the broken conductor pickup FlexLogic operand.Figure 5–153: BROKEN CONDUCTOR DETECTION LOGICSETTINGSBROKEN CONDUCTOR 1FUNCTION:Enabled = 1ANDBROKEN CONDCT 1 BLK:Off = 0SETTINGSBROKEN CONDUCTOR 1SOURCE:I2FLEXLOGIC OPERANDBROKEN CONDUCT 1 OPI1IaIbIcANDSETTINGBROKEN CONDUCTOR 1I1 MIN :| I1 | > I1 MIN| Ia | < I1 MIN| Ib | < I1 MIN| Ic | < I1 MIN| Ia’ | - | Ia | > 0.05pu| Ib’ | - | Ib | > 0.05pu| Ic’ | - | Ic | > 0.05puWhere I’ is 4 cycles oldANDANDOROne phase current lossdetectionRUN2 cyc0ANDORSETTINGBROKEN CONDUCTOR 1I1 MAX :RUN| I1 | < I1 MAX| I2 | / | I1 |> RATIOBROKEN CONDUCTOR 1I2/I1 RATIO :tPKP0SETTINGBROKEN CONDUCTOR 1I1 MAX :FLEXLOGIC OPERANDBROKEN CONDUCT 1 PKP
