Sel SEL-787 User Manual (English)

Questions and Answers:

M
Mrs. Victoria Vazquez MDAug 2, 2025
What to do if Sel SEL-787 does not respond to commands from a device connected to the serial port?
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  Theodore KimAug 2, 2025
  If your Sel relay isn't responding to commands from a connected device, start by verifying the cable connections. Next, ensure that the cable is the correct type by verifying the cable pinout. Then, check that the relay and device are set to the correct baud rate and that there are no other parameter mismatches in the device software setup. Lastly, if the relay serial port has received an XOFF, type to send the relay XON and restart communications.
S
sarahrogersAug 8, 2025
What to do if Sel SEL-787 does not respond to faults?
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  Jay MartinezAug 8, 2025
  If your Sel relay isn't responding to faults, it could be due to several reasons. First, double-check the relay settings to ensure they are correct. Also, verify the test source settings. Another potential cause is a wiring error in the current or voltage input; ensure the input wiring is correct. Finally, a failed relay self-test could be the culprit; check the self-test results using the front-panel RELAY STATUS function.
L
lindaparkAug 14, 2025
Why Sel SEL-787 does not accurately measure voltages or currents?
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  ljohnsonAug 15, 2025
  If your Sel relay isn't accurately measuring voltages or currents, start by checking the input wiring for any errors. Also, verify the instrument transformer ratios, connections, and associated settings (CTR1, CTR2, CTRN, or PTR). Finally, ensure that the voltage neutral terminal (N) is properly grounded by verifying the wiring and connections.
Z
zsalinasAug 19, 2025
How to fix a dark ENABLED front-panel LED on Sel SEL-787?
- E
  Erica GonzalesAug 20, 2025
  If the ENABLED front-panel LED on your Sel relay is dark, first verify that input power is present and check the fuse continuity. If power is present and the fuse is intact, view the self-test failure message on the front-panel display to diagnose the issue.
B
Brianna HarrisAug 26, 2025
How to fix Sel SEL-787 Relays front-panel display when it does not show characters?
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  Melissa BushAug 26, 2025
  If the front-panel display on your Sel relay is blank, first press the ESC pushbutton to activate the display, in case it has timed out. If that doesn't work, verify input power and fuse continuity to ensure the relay is energized.

Sel SEL-787 Specifications

General

Frequency	50/60 Hz
Communication Protocols	IEC 61850, DNP3, Modbus
Display	LCD
Protection Functions	Overcurrent, Overvoltage, Undervoltage, Frequency
Mounting	Panel
DC Voltage	125 V DC
Current Input	1 A
Operating Temperature	-40 to +85 °C
Category	Relay