GE B30 Instruction Manual page 319

5 SETTINGS
The dcmA output settings are described below.
• DCMA OUTPUT H1 SOURCE: This setting specifies an internal analog value to drive the analog output. Actual values
(FlexAnalog parameters) such as power, current amplitude, voltage amplitude, power factor, etc. can be configured as
sources driving dcmA outputs. Refer to Appendix A for a complete list of FlexAnalog parameters.
• DCMA OUTPUT H1 RANGE: This setting allows selection of the output range. Each dcmA channel may be set inde-
pendently to work with different ranges. The three most commonly used output ranges are available.
• DCMA OUTPUT H1 MIN VAL: This setting allows setting the minimum limit for the signal that drives the output. This
setting is used to control the mapping between an internal analog value and the output current. The setting is entered
in per-unit values. The base units are defined in the same manner as the FlexElement base units.
• DCMA OUTPUT H1 MAX VAL: This setting allows setting the maximum limit for the signal that drives the output. This
setting is used to control the mapping between an internal analog value and the output current. The setting is entered
in per-unit values. The base units are defined in the same manner as the FlexElement base units.
The
DCMA OUTPUT H1 MIN VAL
the
DCMA OUTPUT H1 SOURCE
NOTE
Three application examples are described below.
EXAMPLE: CURRENT MONITORING
The phase A current (true RMS value) is to be monitored via the H2 current output working with the range from 4 to 20 mA.
The CT ratio is 5000:5 and the maximum load current is 4200 A. The current should be monitored from 0 A upwards, allow-
ing for 50% overload.
The phase current with the 50% overload margin is:
The base unit for current (refer to the FlexElements section in this chapter for additional details) is:
The minimum and maximum power values to be monitored (in pu) are:
minimum current
The following settings should be entered:
DCMA OUTPUT H2 SOURCE
: "4 to 20 mA"
DCMA OUTPUT H2 RANGE
DCMA OUTPUT H2 MIN VAL
DCMA OUTPUT H2 MAX VAL
The worst-case error for this application could be calculated by superimposing the following two sources of error:
• ±0.5% of the full scale for the analog output module, or
• ±0.25% of reading or ±0.1% of rated (whichever is greater) for currents between 0.1 and 2.0 of nominal
For example, at the reading of 4.2 kA, the worst-case error is max(0.0025  4.2 kA, 0.001  5 kA) + 0.504 kA = 0.515 kA.
EXAMPLE: VOLTAGE MONITORING
A positive-sequence voltage on a 400 kV system measured via source 2 is to be monitored by the dcmA H3 output with a
range of 0 to 1 mA. The VT secondary setting is 66.4 V, the VT ratio setting is 6024, and the VT connection setting is
"Delta". The voltage should be monitored in the range from 70% to 110% of nominal.
The minimum and maximum positive-sequence voltages to be monitored are:
V 0.7
=
min
The base unit for voltage (refer to the FlexElements section in this chapter for additional details) is:
GE Multilin
and
DCMA OUTPUT H1 MAX VAL
is set to FlexAnalog value based on power factor measurement).

I 1.5 4.2 kA
=
max
I
=
BASE
0 kA
----------- - 0 pu, maximum current
= =
5 kA
: "SRC 1 Ia RMS"
: "0.000 pu"
: "1.260 pu"
400 kV

------------------ -
161.66 kV,
=
3

V 0.0664 kV 6024
=
BASE
B30 Bus Differential System
5.9 TRANSDUCER INPUTS AND OUTPUTS
settings are ignored for power factor base units (i.e. if
6.3 kA
=
5 kA
6.3 kA
---------------- - 1.26 pu
= =
5 kA
    6.3 kA 
0.005 20 4
– =
400 kV

------------------ -
V 1.1 254.03 kV
= =
max
3
400 kV
=
(EQ 5.21)
(EQ 5.22)
(EQ 5.23)

0.504 kA
(EQ 5.24)
(EQ 5.25)
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