GE MI-869 - Page 317

CHAPTER 4: SETPOINTS PROTECTION
869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL 4–199
Figure 4-66: Neutral Directional Overcurrent Protection logic diagram
FLEXLOGIC OPERAND
FLEXLOGIC OPERAND
SETTING SETTING SETTING SETTING
SETTINGS SETTING SETTING
NEUTRAL DIR OC FUNCTION: NEUTRAL DIR OC POL VOLT: NEUTRAL DIR OC POLARIZING: BLOCK:
NEUTRAL DIR OC FWD LIMIT ANGLE: NEUTRAL DIR OC FWD ECA: NEUTRAL DIR OC REV LIMIT ANGLE: NEUTRAL DIR OC FWD PICKUP: NEUTRAL DIR OC REV PICKUP: NEUTRAL DIR OC POS-SEQ RESTRAINT
Ntrl Dir OC FWD
Ntrl Dir OC REV
Disabled=0 Measured VX Voltage Calculated V_0
}
}
Current Ground Crt (IG) Zero Seq Crt (I_0) Dual
NOTE:
1) CURRENT POLARIZING IS POSSIBLE ONLY IN RELAYS WITH
THE GROUND CURRENT INPUTS CONNECTED TO
AN ADEQUATE CURRENT POLARIZING SOURCE
2) POSITIVE SEQUENCE RESTRAINT IS NOT APPLIED WHEN
I_1 IS BELOW 0.8 x CT
Off=0 Enabled=1
AND
AND AND
AND
AND
AND
AND
OR OR
OR
OR
IG 0.05xCT
3( I_0 - K I_1) PICKUP 3(I_0 - K I_1 ) PICKUP
Voltage Polarization
Current Polarization
-3V_0
3I_0
FWD
FWD FWD
REV REV
REV
RUN RUN RUN RUN
1.25 cy
1.5 cy
NEUTRAL DIR OC POS- SEQ RESTRAINT:
892716A1.cdr
TO NEUTRAL TOC AND IOC ELEMENTS
TO NEUTRAL TOC AND IOC ELEMENTS
AND