Schweitzer Engineering Laboratories SEL-749M - Table 10.3 Phase Current Measuring Accuracy; Figure 10.4 Current Source Connections

10.7
Date Code 20080918 Instruction Manual SEL-749M Relay
Testing and Troubleshooting
Commissioning Tests
Figure 10.4 Current Source Connections
Step 4. Set each phase current magnitude equal to the values listed in
Column 1 of Table 10.3.
Use the front-panel to view the phase current values. The relay
should display the applied current magnitude times the CTR1
setting.
Current Imbalance Element Accuracy
Step 1. Connect the current source to the relay, as shown in
Figure 10.4.
Step 2. Using the front-panel
SET/SHOW function or the serial port
SHOW command, record the CTR1, PHROT, and FLA1
setting values.
Step 3. Set the phase current angles to apply balanced three-phase
currents in accordance with the PHROT setting. Refer to
Figure 10.2.
Step 4. Apply the appropriate magnitude for each phase current, as
shown in Column 1 of Table 10.4.
Table 10.3 Phase Current Measuring Accuracy
|I|
Applied
(A
secondary)
a
a
I
NOM
= rated secondary amps (1 or 5)
Expected
Reading
CTR1 x |I|
A–Phase
Reading
(A primary)
B–Phase
Reading
(A primary)
C–Phase
Reading
(A primary)
0.2 x I
NOM
0.9 x I
NOM
1.6 x I
NOM
SEL-749M
Current
Test
Source
IA
IB
IC
IC
IB
IA
IN
Z01
Z02
Z03
Z04
Z05
Z06
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