2.40
SEL-351S Relay Instruction Manual Date Code 20080103
Installation
Circuit Board Connections
!
CAUTION
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 2.32–Figure 2.35 and perform the following steps:
Step 1. De-energize the relay.
On plug-in connector versions this can be easily accomplished
by removing the connector at rear-panel terminals Z25 and Z26
.
Step 2. Remove any cables connected to serial ports on the front and
rear panels.
Step 3. Loosen the six front-panel screws (they remain attached to the
front panel), and remove the relay front panel.
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.
Step 4. Remove the 64-pin ribbon cable from the front panel by
pushing the extraction ears away from the connector.
Step 5. Remove the ribbon cable connected to the front panel DB9
connector.
Step 6. Remove the auxiliary pushbutton and LED connectors from the
magnetics/auxiliary pushbutton board, if equipped.
NOTE: Be sure to place the front
panel on an ESD-safe workstation to
prevent ESD damage.
Step 7. 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.
The main board on the SEL-351S is the top board in the
chassis. If the relay has an extra I/O board it is located
underneath the main board. The magnetics/auxiliary
pushbutton board and power supply are mounted to the bottom
of the chassis. It is not necessary to remove the magnetics/
auxiliary pushbutton board from the chassis to access the
associated circuit board jumpers.
Step 8. On plug-in connector 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.
Step 9. 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 be 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.
Step 10. Grasp the drawout assembly of the board and pull the assembly
from the relay chassis.
Step 11. Locate the jumper(s) or battery to be changed (refer to
Figure 2.32–Figure 2.35).
Make the desired changes. Note that the output contact jumpers
are soldered in place.
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