Date Code 20001006 Installation 2-25
SEL-351 Instruction Manual
CIRCUIT BOARD CONNECTIONS
Accessing the Relay Circuit Boards
To change circuit board jumpers or replace the clock battery on the relay main board, refer to
Figure 2.15 through Figure 2.18 and take the following steps:
1. Deenergize the relay. On Connectorized versions this can be easily accomplished by removing
the connector at rear-panel terminals Z15 and Z16 or Z25 and Z26
2. Remove any cables connected to serial ports on the front and rear panels.
3. Loosen the six front-panel screws (they remain attached to the front panel), and remove the
relay front panel.
CAUTION
!
The relay contains devices sensitive to Electrostatic Discharge
(ESD). When working on the relay with front or top cover removed,
work surfaces and personnel must be properly grounded or
equipment damage may result.
4. Each circuit board corresponds to a row of rear-panel terminal blocks or connectors and is
affixed to a drawout tray. Identify which drawout tray needs to be removed. SEL-351 Relay
models 0351x0 and 0351xT have only a main board. Models 0351x1 and 0351xY have an
extra I/O board below the main board.
5. On Connectorized versions, remove the rear-panel connectors that correspond to the circuit
board you wish to remove by loosening the screws on either end of each connector. Removal
of the extra I/O board also requires removal of the main board (because the LCD on the main
board is in the way).
6. Disconnect circuit board cables as necessary to allow the desired board and drawout tray to
be removed. Removal of the extra I/O board requires removal of the main board first.
Ribbon cables can me removed by pushing the extraction ears away from the connector. The
6-conductor power cable can be removed by grasping the power connector wires and pulling
away from the circuit board.
7. Grasp the drawout assembly of the board and pull the assembly from the relay chassis.
8. Locate the jumper(s) or battery to be changed (refer to Figure 2.15 through Figure 2.18).
Make the desired changes. Note that the output contact jumpers are soldered in place.
9. When finished, slide the drawout assembly into the relay chassis. Reconnect the cables
removed in step 6. Replace the relay front-panel cover.
10. Replace any cables previously connected to serial ports.
11. Replace any rear-panel connectors removed in step 5.
12. Reenergize the relay. On Connectorized versions, replace the power connector at rear-panel
terminals Z15 and Z16 or Z25 and Z26.
Courtesy of NationalSwitchgear.com
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