GE D60, Инструкция по эксплуатации

Страница: 502 / 826

5-368 D60 Line Distance Protection System GE Multilin
5.9 TRANSDUCER INPUTS AND OUTPUTS 5 SETTINGS
5
(EQ 5.38)
The base unit for current (refer to the FlexElements section in this chapter for additional details) is:
(EQ 5.39)
The minimum and maximum power values to be monitored (in pu) are:
(EQ 5.40)
The following settings should be entered:
DCMA OUTPUT H2 SOURCE
: “SRC 1 Ia RMS”
DCMA OUTPUT H2 RANGE
: “4 to 20 mA”
DCMA OUTPUT H2 MIN VAL
: “0.000 pu”
DCMA OUTPUT H2 MAX VAL
: “1.260 pu”
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:
(EQ 5.41)
The base unit for voltage (refer to the FlexElements section in this chapter for additional details) is:
(EQ 5.42)
The minimum and maximum voltage values to be monitored (in pu) are:
(EQ 5.43)
The following settings should be entered:
DCMA OUTPUT H3 SOURCE
: “SRC 2 V_1 mag”
DCMA OUTPUT H3 RANGE
: “0 to 1 mA”
DCMA OUTPUT H3 MIN VAL
: “0.404 pu”
DCMA OUTPUT H3 MAX VAL
: “0.635 pu”
The limit settings differ from the expected 0.7 pu and 1.1 pu because the relay calculates the positive-sequence quantities
scaled to the phase-to-ground voltages, even if the VTs are connected in “Delta” (see the
Metering Conventions section in
chapter 6), while at the same time the VT nominal voltage is 1 pu for the settings. Consequently the settings required in this
example differ from naturally expected by the factor of
.
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
• ±0.5% of reading
For example, under nominal conditions, the positive-sequence reads 230.94 kV and the worst-case error is
0.005 x 230.94 kV + 1.27 kV = 2.42 kV.
I
max
1.5 4.2 kA

6.3 kA
= =
I
BASE
5 kA
=
minimum current
0 kA
5 kA
------------
0 pu, maximum current
6.3 kA
5 kA
-----------------
1.26 pu
= = = =
0.005 20 4
–
 
6.3 kA
  
0.504 kA

=
V
min
0.7
400 kV
3
------------------- 
161.66 kV, V
max
1.1
400 kV
3
------------------- 
254.03 kV
= = = =
V
BASE
0.0664 kV 6024

400 kV
= =
minimum voltage
161.66 kV
400 kV
---------------------------
0.404 pu, maximum voltage
254.03 kV
400 kV
---------------------------
0.635 pu
= = = =
3
0.005 1 0
–
  
254.03 kV
 
1.27 kV

=