CHAPTER 5: SETTINGS
CONTROL ELEMENTS
N60 NETWORK STABILITY AND SYNCHROPHASOR MEASUREMENT SYSTEM – INSTRUCTION MANUAL
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5
Application example 2
The phase A current (true RMS value) is to be sent via remote outputs (MMS GOOSE) to several remote IEDs (DNA points 14
through 20). The CT ratio is 5000:5 and the maximum load current is 4200 A. The current should be monitored allowing for
50% overload.
•
Phase current with the 50% overload margin: I
max
= 1.5 x 4.2 kA = 6.3 kA
•
UR base unit for current: I
BASE
= 5 kA (see FlexElements section for further details)
•
Minimum current to be monitored (pu): 6.3 kA/5 kA = 1.26 pu
The following settings are applied:
DIGITIZER 1 SOURCE
= “SRC 1 Ia RMS” and
DIGITIZER 1 LIMIT
= “1.260 pu”
Using these settings, the output represents current magnitude with the scale of 127 per 6.3 kA; for example, one count of a
digitizer output represents 6.3 kA / 127 = 49.6 A.
The remote outputs are configured as follows:
DNA- 14 OPERAND
: “DIGITIZER 1 BIT 0”
DNA- 18 OPERAND
: “DIGITIZER 1 BIT 4”
DNA- 15 OPERAND
: “DIGITIZER 1 BIT 1”
DNA- 19 OPERAND
: “DIGITIZER 1 BIT 5”
DNA- 16 OPERAND
: “DIGITIZER 1 BIT 2”
DNA- 20 OPERAND
: “DIGITIZER 1 BIT 6”
DNA- 17 OPERAND
: “DIGITIZER 1 BIT 3”
As the input signal (true RMS) is always positive, the sign bit can be ignored and only seven points need to be exchanged.
On the receiving location, incoming bits 14 through 20 are configured to drive remote inputs. The latter together with the
FlexLogic constant “Off” for the sign bit is configured accordingly to use the incoming information (typically via the eight-
bit comparator feature).
The table illustrates this application for four sample current values.
Table 5-42: Sample current values
5.8.13 8-bit comparators
SETTINGS
CONTROL ELEMENTS
8-BIT COMPARATORS
8-BIT COMPARATOR 1(6)
Current
N
out
B7... B0
1.00 kA
20
00010100
2.50 kA
50
00110010
4.20 kA
85
01010101
6.00 kA
121
01111001
8-BIT
COMPARATOR 1
8BIT COMP 1
FUNCTION: Disabled
Range: Disabled, Enabled
8BIT COMP 1 ARG A0:
Off
Range: FlexLogic operand
8BIT COMP 1 ARG A1:
Off
Range: FlexLogic operand
8BIT COMP 1 ARG A7:
Off
Range: FlexLogic operand
8BIT COMP 1 ARG B0:
Off
Range: FlexLogic operand
8BIT COMP 1 ARG B1:
Off
Range: FlexLogic operand