GE N60 Instruction Manual page 337

5 SETTINGS
"
DIGITIZER 1 BIT 0
8 BIT COMP 1 ARG B0:
"
DIGITIZER 1 BIT 1
8 BIT COMP 1 ARG B1:
"
DIGITIZER 1 BIT 2
8 BIT COMP 1 ARG B2:
"
8 BIT COMP 1 ARG B3: DIGITIZER 1 BIT 3
3. The two power values are to be added, therefore set
4. The alarm should be established when the total power in either direction (import or export) is above the threshold,
therefore set
8BIT COMP 1 INPUT MODE
5. The alarm should also be established when the total power is above the threshold, therefore set the
to "Over".
TION
6. The digitized power values should be scaled to meaningful values. Assuming that MW are to be used for comparison
and display, set
8BIT COMP 1 SCALE FACTOR
actual values represent the remote (UR-1), local (UR-2), and total power values in MW.
Out
7. The alarm should also be established when the total power is greater than 2500 MW. As such, set
to "2500.00".
8. The alarm should be cleared when the total power is less than 2000 MW. As such, the hysteresis setting should be
2500 – 2000 = 500 MW. Set
9. Using the timing requirements, set
FlexLogic operand should be used to set the alarm.
8BIT COMP 1 OP
10. For monitoring and telemetry purposes, the digitized power values should be scaled to meaningful values. Assuming
MW to be displayed, set
and will represent the remote (UR-1), local (UR-2), and total power values in MW.
1 B 8BIT COMP 1 Out
For the User-definable displays at UR-2 (optional):
To display the remote and total power values the following screen may be set up:
: "REMOTE MW: ~"
DISP 1 TOP LINE
: "TOTAL MW: ~"
DISP 1 BOTTOM LINE
: "8100" (Modbus register address of
DISP 1 ITEM 1
: "8104" (Modbus register address of
DISP 1 ITEM 2
Analysis of metering errors at UR-2:
The remote and local power values are measured with the maximum error of ±1% of reading (at power factors above 0.8).
The digitization (round up) error is 0.2% of full scale, or 0.002  2  1500 MW = 6 MW. Consequently,
• Remote power is measured at UR-2 with a worst-case error of ± (1% of reading + 6 MW).
• Total power is measured at UR-2 with a worst-case error of ± (1% of UR-1 reading + 1% of UR-2 reading + 12 MW).
For example, with a reading of 1020 MW at UR-1 and 800 MW at UR-2, the remote power is measured at UR-2 with the
worst-case error of ±(0.01  1020 MW + 6 MW) = ±16.2 MW, or ±1.6%. The reading for remote power at UR-2 is the prod-
uct of the digitized value sent from UR-1 and received at UR-2 and the scale factor setting; that is,
Total Power at UR-1
Therefore, the reading for the remote power at UR-2 is 1015.7 MW, versus 1020 MW at the point of origin (UR-1).
The total power is measured at UR-2 with the worst-case error of ± (0.01  1020 MW + 0.01  800 MW + 12 MW) =
±30.2MW, or ±1.7%. The reading for the total power at UR-2 is the sum of the digitized value sent from UR-1 and received
at UR-2 and the digitized value at UR-2 multiplied by the scaling factor; that is,
Total Power at UR-2
Therefore, the reading for the total power at UR-2 is 1818.7 MW, versus a true total of 1020 MW + 800 MW = 1820 MW.
GE Multilin N60 Network Stability and Synchrophasor Measurement System
"
8 BIT COMP 1 ARG B4:
"
8 BIT COMP 1 ARG B5:
"
8 BIT COMP 1 ARG B6:
"
8 BIT COMP 1 ARG B7:
8BIT COMP 1 ADD/SUB
to "Absolute".
to "11.81". In this way, the
to "500".
8BIT COMP 1 HYSTERESIS
8BIT COMP 1 PICKUP DELAY
to "11.81". In this way, the actual values
8BIT COMP 1 SCALE FACTOR
8BIT COMP 1 A
8BIT COMP 1 Out
1020 MW
 
------------------------- -
round
=
 
1500 MW

86 11.81 MW
=
1020 MW
 

------------------------- -
round 127
=
 
1500 MW
  
86 68 11.81 MW
= +
"
DIGITIZER 1 BIT 4
"
DIGITIZER 1 BIT 5
"
DIGITIZER 1 BIT 6
"
DIGITIZER 1 BIT 7
to "On".
8BIT COMP 1 A
to "0.050" and
8BIT COMP 1 RESET DELAY
)
)
 
 
127 11.81 MW
 
1015.7 MW
=
800 MW
   

------------------------- -
round 127
+
   
1500 MW
1818.7 MW
=
5.7 CONTROL ELEMENTS
"
"
"
"
8BIT COMP 1 DIREC-
, , and
8BIT COMP 1 B 8BIT COMP 1
8BIT COMP 1 PICKUP
to "1.000". The
,
8BIT COMP 1 A 8BIT COMP
(EQ 5.23)

11.81 MW
(EQ 5.24)
5-219
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