GE 845 Instruction Manual page 155

CHAPTER 4: SETPOINTS
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
MMS logical nodes are located. Valid characters for these values are upper and
lowercase letters, numbers, and the underscore (_) character. The first character in the
string must be a letter. This conforms to the IEC 61850 standard.
2. DAI Settings tab
DAI settings contains these features for configuration: MMXU & MSQI logical nodes,
GGIO3 logical node, XCBR logical node.
MMXU & MSQI Logical nodes
Range: 1 to 100.000 %
The MMXU & MSQI deadband settings represent the deadband values used to
determine when to update the MMXU "mag" and "cVal" values from the associated
"instmag" and "instcVal" values. The "mag" and "cVal" values are used for the IEC
61850 buffered and unbuffered reports. The settings correspond to the associated
"db" data items in the CF functional constraint of the MMXU logical node, as per the
IEC 61850 standard. According to IEC 61850-7-3, the db value "shall represent the
percentage of difference between the maximum and minimum in units of 0.001%".
Thus, it is important to know the maximum value for each MMXU measured quantity,
since this represents the 100.00% value for the deadband.
MIN/MAX VALUES FOR MMXU NODES
The equations to calculate minimum (min) and maximum (max) values in the MMXU
nodes are as follows:
Table 4-32: Calculate Min/Max MMXU Node Values
MMXU Node Value
TotW
TotVar
TotVA
TotPF
Hz
HzRte
PPV
PhV
A$phsA, phsB, phsC
To Calculate
max = (Phase CT Primary * 46) * (Phase VT Ratio * 240) / 1000
min = -max
Note that the max is divided by 1000 to convert from W to kW
max = (Phase CT Primary * 46) * (Phase VT Ratio * 240) / 1000
min = -max
max = (Phase CT Primary * 46) * (Phase VT Ratio * 240) / 1000
min = -max
max = 1
min = -1
max = 90
min = 0
max = 15
min = -15
max = Phase VT Ratio * 240
min = 0
max = Phase VT Ratio * 240
min = 0
max = (Phase CT Primary * 46)
min = 0
DEVICE
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