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2.16
SEL-421 Relay
Instruction Manual
Date Code 20171021
Installation
Jumpers
Main Board Jumpers
The jumpers on the main board of the SEL-421 perform these functions:
➤
Temporary/emergency password disable
➤
Circuit breaker and disconnect control enable
➤
Rear serial port +5 Vdc source enable
shows the positions of the main board jumpers. The main board
jumpers are in two locations. The password disable jumper and circuit breaker
control jumper are at the front of the main board. The serial port jumpers are near
the rear-panel serial ports; each serial port jumper is directly in front of the serial
port that it controls.
Password and Circuit Breaker Jumpers
You can access the password disable jumper and circuit breaker control jumper
without removing the main board from the relay cabinet. Remove the SEL-421
front cover to view these jumpers (use appropriate ESD precautions). The pass-
word and circuit breaker jumpers (position number J18 or J21) are located on the
front of the main board, immediately left of the power connector (see
).
There are four jumpers, denoted D, BREAKER, PASSWORD, and A from left to
right (position D is on the left). Position PASSWORD is the password disable
jumper; position BREAKER is the circuit breaker control enable jumper. Posi-
tions D and A are for SEL use.
shows the jumper header with the cir-
cuit breaker/control jumper in the ON position and the password jumper in the
OFF position; these are the normal jumper positions for an in-service relay.
lists the jumper positions and functions.
CAUTION
Do not install a jumper on positions A
or D of the main board J18 header.
Relay misoperation can result if you
install jumpers on positions J18A and
J18D.
Figure 2.18
Jumper Location on the Main Board
Jumper Location
5 4 3 2 1
9 8 7 6
Power Connector
J18 or J21
ON
OFF
PASSWORD
BREAKER
ON
OFF
A
B
C
D
D
A
Table 2.5
Main Board Jumpers (Sheet 1 of 2)
Jumper
Jumper Location
Jumper Position
a
Function
A
Front
OFF
For SEL use only
PASSWORD
Front
OFF
Enable password protection
(normal and shipped position)
ON
Disable password protection
(temporary or emergency only)
Summary of Contents for SEL-421-4
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