U.2.21
Date Code 20090715 User’s Guide SEL-421 Relay
Installation
Jumpers
Serial Port Jumpers
Place jumpers on the main board to connect +5 Vdc to Pin 1 of each of the
three rear-panel EIA-232 serial ports. The maximum current available from
this Pin 1 source is 0.5 A. The Pin 1 source is useful for powering an external
modem. Table 2.6 describes the JMP1, JMP2, and JMP3 positions. Refer to
Figure 2.19 for the locations of these jumpers. The SEL-421 ships with JMP1,
JMP2, and JMP3 OFF (no +5 Vdc on Pin 1).
Changing Serial Port Jumpers
You must remove the main board to access the serial port jumpers. Perform
the following steps to change the JMP1, JMP2, and JMP3 jumpers in an
SEL-421:
Step 1. Follow your company standard to remove the relay from
service.
Step 2. Disconnect power from the SEL-421.
Step 3. Retain the GND connection, if possible, and ground the
equipment to an ESD mat.
Step 4. Remove the communications cable connected to the front-panel
serial port, if applicable.
Step 5. Remove the rear-panel EIA-232 PORT mating connectors.
Unscrew the keeper screws and disconnect any serial cables
connected to the PORT 1, PORT 2, and PORT 3 rear-panel
receptacles.
Step 6. Loosen the four front-panel screws (they remain attached to the
front panel), and remove the relay front panel.
Step 7. Remove the 34-pin ribbon cable from the front panel by
pushing the extraction ears away from the connector.
Step 8. Disconnect the power, the interface board, and the analog input
board cables from the main board.
Step 9. Remove the screw terminal connectors.
a. Loosen the attachment screws at each end of the 100-
addresses screw terminal connectors.
b. Pull straight back to remove.
Step 10. Carefully pull out the drawout assembly containing the main
board.
Table 2.6 Main Board Jumpers—JMP1, JMP2, and JMP3
a
a
ON is the jumper shorting both pins of the jumper. Place the jumper over one pin only for OFF.
Jumper
Jumper
Location
Jumper
Position
Function
JMP1 Rear OFF Serial PORT 3, Pin 1 = not connected
ON Serial PORT 3, Pin 1 = +5 Vdc
JMP2 Rear OFF Serial PORT 2, Pin 1 = not connected
ON Serial PORT 2, Pin 1 = +5 Vdc
JMP3 Rear OFF Serial PORT 1, Pin 1 = not connected
ON Serial PORT 1, Pin 1 = +5 Vdc
Contact with instrument terminals
can cause electrical shock that can
result in injury or death.
!
DANGER
Have only qualified personnel service
this equipment. If you are not
qualified to service this equipment,
you can injure yourself or others, or
cause equipment damage.
!
WARNING
Equipment components are sensitive
to electrostatic discharge (ESD).
Undetectable permanent damage
can result if you do not use proper
ESD procedures. Ground yourself,
your work surface, and this
equipment before removing any
cover from this equipment. If your
facility is not equipped to work with
these components, contact SEL
about returning this device and
related SEL equipment for service.
!
CAUTION
Courtesy of NationalSwitchgear.com
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