11.8
SEL-751 Relay Instruction Manual Date Code 20170927
Testing and Troubleshooting
Commissioning Tests
Current Unbalance Metering Accuracy
Step 1. Connect the current source to the relay, as shown in
Figure 11.4.
Step 2. Using the front-panel
SET/SHOW function or the serial port SHO
command, record the CTR and PHROT setting values.
Step 3. Set the phase current angles to apply balanced three-phase
currents in accordance with the PHROT setting. Refer to
Figure 11.2.
Step 4. Apply the appropriate magnitude for each phase current, as
shown in Column 1 of Table 11.4.
Power and Power Factor Measuring Accuracy
Wye-Connected Voltages
Perform the following steps to test wye-connected voltages:
Step 1. Connect the current source to the relay, as shown in
Figure 11.4.
Step 2. Connect the voltage source to the relay, as shown in
Figure 11.5. Make sure that DELTA_Y := WYE.
Figure 11.5 Wye Voltage Source Connections
Table 11.4 Current Unbalance Measuring Accuracy
|I| Apply (A secondary) Expected Reading (%) Actual Reading (%)
|IA| = 0.9 •
I
NOM
7%
|IB| = I
NOM
|IC| =
I
NOM
|IA| = 0.75 •
I
NOM
17%
|IB| = I
NOM
|IC| =
I
NOM
|IA| =
I
NOM
12%
|IB| = 1.2 • I
NOM
|IC| = 1.2 •
I
NOM
|IA| = 0.9 •
I
NOM
13%
|IB| = 1.1 • I
NOM
|IC| = 1.1 •
I
NOM
SEL-751
Z09
Z10
Z11
Z12
Voltage
Test
Source
VA
VB
VC
N
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