GE C30 Instruction Manual page 296

PRODUCT SETUP
Scaling using factors <1 can be required in such cases. The calculation is outlined in the IEC 60870-5-103 chapter of
the UR Family Communications Guide. Two examples follow, where you decide factors a and b.
Example 1: Nominal power Pn = 100 MW = 100000 KW (power is transmitted in KW)
Since P can be both positive and negative:
Transmitted power Pt = (4095/(Pn*2.4)) * P = (4095/(100000 * 2.4) ) * P
= 0.017 * P
a = 0.017
b = 0
Pt = 0.017 * P
For a max power 100000 KW * 2.4 = 240000 KW, we transmit
Pt = 0.017 * 240000 = 4080
A value above 240 MW is indicated by overflow.
Example 2: Nominal voltage Vn = 500000 V
Since RMS voltage V can be only positive:
Transmitted voltage Vt = (8191/(Vn*2.4)) * V - 4096 =
= (8191/(500000 * 2.4) ) * V - 4096 = 0.0068 * V - 4096
a = 0.0068
Since the step is in increments of 0.001, we round it at:
a = 0.006
5
b = -4096
Vt = 0.006 * V - 4096
For max voltage 500000 V * 2.4 = 1200000 V, we transmit
Vt = 0.006 * 1200000 - 4096 = 7200 - 4096 = 3104
SETTINGS  PRODUCT SETUP  COMMUNICATIONS  IEC 60870-5-103  IEC103 COMMANDS
 IEC103 COMMANDS

 COMMAND 0

 COMMAND 31

5-102
 COMMAND 0


 COMMAND 1



 COMMAND 31


COMMAND 0 FUN:

0
COMMAND 0 INF:

0
COMMAND 0 ON:

Off
COMMAND 0 OFF:

Off

COMMAND 31 FUN:

0
CHAPTER 5: SETTINGS
See below
Range: 0 to 255 in steps of 1
Range: 0 to 255 in steps of 1
Range: Virtual input
Range: Virtual input
Range: 0 to 255 in steps of 1
C30 CONTROLLER SYSTEM – INSTRUCTION MANUAL