GE D90 Plus Instruction Manual page 437

CHAPTER 8: AUTOMATION
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
When DELTA_V is greater than 0.5 volts for more than 30 seconds (the sum of timers 2 and
3), the tap changer control is in auto mode, no overcurrent condition exists, and there is no
lockout, then a LOWER command is issued via analog virtual output 4. If the voltage
remains high, then subsequent LOWER commands are issued at five second intervals.
Figure 358: Lower command automation logic
When DELTA_V is less than –0.5 volts for more than 30 seconds (the sum of timers 2 and 3),
the tap changer control is in auto mode, no overcurrent condition exists, and there is no
lockout, then a RAISE command is issued. If the voltage remains low, then subsequent
RAISE commands are issued at five second intervals.
AUTOMATION LOGIC
429