GE 845 - Page 296

4–168 845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
PROTECTION CHAPTER 4: SETPOINTS
Figure 4-56: Phase Directional Overcurrent Protection logic diagram
894156A2.cdr
SETPOINT
FUNCTION: Disabled = 0 Enabled = 1
SETPOINT
BLOCK: Off = 0
Voltage Polarization
Vpol
FWD
REV
RUN
SETPOINT
ECA
I > 0.05 x CT
AND
OR
ACTUAL VALUES
Ia Seq = ABC Seq = ACB Vbc Vcb
SETPOINT
REV WHEN V MEM EXP No
Yes
SETPOINT
POLARIZING V TRESHOLD Vact if V>= V minimum Vmem if V< Vminimum V>= V minimum
MEMORY TIMER
1 cycle
1 sec
AND
AND
PHASE B LOGIC SIMILAR TO PHASE A PHASE C LOGIC SIMILAR TO PHASE A
Ph Dir OC REV A
FLEXLOGIC OPERANDS
Ph Dir OC REV B
FLEXLOGIC OPERANDS
Ph Dir OC REV C
FLEXLOGIC OPERANDS
To phase TOC & IOC elements To phase TOC & IOC elements To phase TOC & IOC elements
OR
Ph Dir OC REV
FLEXLOGIC OPERANDS
SETPOINTS
SIGNAL INPUT: CT Bank 1 - J1