10.7
Date Code 20100129
Instruction Manual
SEL-751A Relay
Testing and Troubleshooting
Commissioning Tests
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
Step 2. Connect the voltage source to the relay, as shown in
. Make sure that DELTA_Y := WYE.
Figure 10.4
Wye Voltage Source Connections
Step 3. Using the front-panel
SET/SHOW
or the serial port
SHOW
command, record the CTR, PTR, and PHROT setting values.
Step 4. Apply the current and voltage quantities shown in Column 1 of
.
Values are given for PHROT := ABC and PHROT := ACB.
Step 5. Use the front-panel
METER
function or the serial port
MET
command to verify the results.
|IA| = 0.9 •
I
NOM
13%
|IB| = 1.1 •
I
NOM
|IC| = 1.1 •
I
NOM
Table 10.3
Current Unbalance Measuring Accuracy
(Sheet 2 of 2)
|I| Applied (A secondary)
Expected Reading (%)
Actual Reading (%)
SEL-751A
E01
E02
E03
E04
Voltage
Test
Source
VA
VB
VC
VN
Table 10.4
Power Quantity Accuracy—Wye Voltages
(Sheet 1 of 2)
Applied Currents and Voltages
Real Power
(kW)
Reactive Power (kVAR)
Power Factor
(pf)
PHROT := ABC
Ia = 2.5
∠−26
Ib = 2.5
∠−
146
Ic = 2.5
∠
+94
Expected:
P = 0.4523 • CTR • PTR
Expected:
Q = 0.2211 • CTR • PTR
Expected:
pf = 0.90 lag
Va = 67
∠
0
Vb = 67
∠−
120
Vc = 67
∠
+120
Measured:
Measured:
Measured:
Summary of Contents for 751A
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