Sel 751A - Table 2.13 Jumper Functions and Default Positions

2.13
Date Code 20100129 Instruction Manual SEL-751A Relay
Installation
I/O Configuration
Pins labeled A bypass the password requirement, pins labeled B enable
breaker control, and pins labeled C force the relay to the SEL operating
system called SEL
BOOT. In the unlikely event that the SEL-751A suffers an
internal failure, communications with the relay may be compromised. Forcing
the relay to SEL
BOOT provides a means of downloading new firmware. To
force the relay to SEL
BOOT, position the jumper in Position C, as shown in
Figure 2.7 (SEL
BOOT forced). When forced to SELBOOT, you can only
communicate with the relay via the front-panel port.
To gain access to Level 1 and Level 2 command levels without passwords,
position the jumper in position A, as shown in Figure 2.7 (Password
bypassed). Although you gain access to Level 2 without a password, the alarm
contact still closes momentarily when accessing Level 2. Table 2.13 tabulates
the functions of the three sets of pins and jumper default positions.
Table 2.13 Jumper Functions and Default Positions
Pins Jumper Default Position Description
A Not bypassed (requires password) Password bypass
B Off (breaker control disabled) Enable breaker control
a
a
Enable/Disable serial port, front panel, and Fast Operate commands for breaker control.
C Not bypassed (not forced SELBOOT) Forced SELBOOT