GE Digital Energy L30, Instruction Manual, Page: 427 / 644

GE Multilin L30 Line Current Differential System 9-9
9 THEORY OF OPERATION 9.1 OVERVIEW
9
Time stamp values are snapshots of the local 256 bit sample counter taken at the time of the transmission or receipt of the
first message in a time stamp sequence. This could be done either in software or hardware, provided the jitter is limited to
less than plus or minus 130

s. A fixed bias in the time stamp is acceptable, provided it is the same for all terminals.
Figure 9–2: ROUND TRIP DELAY AND CLOCK OFFSET COMPUTATION FROM TIME STAMPS
831729A2.CDR
Relay 1
Send T2
i-3
Clocks mismatch
Send T1
i-2
Send T2
i-2
Send T1
i-1
Send T2
i-1
Store T2
i-2
Store T1
i-2
Capture T2 T1
i-1, i
T1
i
Capture T1 T2
i-1, i
T2
i
Slow down
Speed up
Send T1
i-3
Store T1
i-3
Store T2
i-3
Capture T1
i-2
T1
i-2
8.3 ms
8.3 ms
Capture T2
i-2
T2
i-2
T1
i-1
T2
i-1
( T1 T2 T2 T1 )
i -3, i-2, i -1, i
( T2 T1 T1 T2 )
i -3, i -2, i-1, i
Calculate 1, 1.
δ θ
Calculate 2, 2.
δ θ
COMMUNICATION PATH
t 2 t 1
Relay 2
8.3 ms
8.3 ms
8.3 ms