8.3
Date Code 20100129
Instruction Manual
SEL-751A Relay
Front-Panel Operations
Human-Machine Interface
Front-Panel
Automatic Messages
The relay displays automatic messages, overriding the rotating display, under
the conditions described in
, with the relay failure having the highest
priority, followed by trip and alarm when the Front Panel setting
FP_AUTO := OVERRIDE.
If the Front Panel setting FP_AUTO := ROTATING, then the rotating display
messages continue and any TRIP or ALARM message is added to the rotation.
Relay failure will still override the rotating display.
Front-Panel Security
Front-Panel Access Levels
The SEL-751A front panel typically operates at Access Level 1 and provides
viewing of relay measurements and settings. Some activities, such as editing
settings and controlling output contacts, are restricted to those operators who
know the Access Level 2 passwords.
In the figures that follow, restricted activities are indicated by the padlock
symbol.
Figure 8.2
Access Level Security Padlock Symbol
Before you can perform a front-panel menu activity that is marked with the
padlock symbol, you must enter the correct Access Level 2 passwords. After
you have correctly entered the password, you can perform other Access
Level 2 activities without reentering the password.
Access Level 2 Password Entry
When you try to perform an Access Level 2 activity, the relay determines
whether you have entered the correct Access Level 2 password since the front-
panel inactivity timer expired. If you have not, the relay displays the screen
shown in
for you to enter the password.
Table 8.1
Front-Panel Automatic Messages (FP_AUTO := OVERRIDE)
Condition
Front-Panel Message
Relay detecting any failure
Displays the type of latest failure (see
Relay trip has occurred
Displays the type or cause of the trip. Refer to
for a list of trip display messages.
Relay alarm condition has
occurred
Displays the type of alarm. The
TRIP
LED is also flashing
during an alarm condition. See
for a list of the
alarm conditions.
Summary of Contents for 751A
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