Compensation Method 2 - GE L30 Instruction Manual

CHAPTER 8: APPLICATION OF SETTINGS
If GPS is enabled at all terminals and the GPS signal is present, the L30 compensates for the channel asymmetry. On the
loss of the GPS signal, the L30 stores the last measured value of the channel asymmetry per channel and compensates for
the asymmetry until the GPS clock is available. However, if the channel was switched to another physical path during GPS
loss conditions, the 87L element must be blocked, since the channel asymmetry cannot be measured and system is no
longer accurately synchronized. The value of the step change in the channel is preset in the L30
menu and signaled by the
87L DIFF 1(2) TIME CHNG
1. Enable channel asymmetry compensation (
contact with the
BLOCK GPS TIME REF
2. Create FlexLogic similar to that shown as follows to block the 87L element on GPS loss if step change in the channel
delay occurs during GPS loss conditions or on a startup before the GPS signal is valid. For three-terminal systems, the
operand must be ORed with the
87L DIFF 1 TIME CHNG
output is reset if the GPS signal is restored and the 87L element is ready to operate.
3. Assign virtual output BLOCK 87L (VO1) to the 87L Current Differential Block setting (
SETTING GROUP  LINE DIFFERENTIAL...  CURRENT DIFFERENTIAL  CURRENT DIFF BLOCK
backup protection, raise an alarm, and perform other functions as per the given protection philosophy.

8.3.3 Compensation method 2

Enable GPS compensation on the loss of the GPS signal at any terminal and block the 87L element after a specified time.
L30 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
FlexLogic operand. To implement this method, use the following steps:
) by setting it to ON. Assign the GPS receiver failsafe alarm
CHNL ASYM COMP
setting.
87L DIFF 2 TIME CHNG
CHANNEL ASYMMETRY COMPENSATION USING GPS
POWER SYSTEM
FlexLogic operand. The Block 87L (VO1)
SETTINGS  GROUPED ELEMENTS 
). It can be used to enable
settings
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