7UT51 v3
Protection Self-Monitoring
12
PRIM-2330C 119
12 Protection Self
-
Monitoring
The relay has self-monitoring features that monitor the
relay hardware, relay software, DC supply power, and
the CT circuitry. If self-monitoring determines that the
relay is not ready, until the condition is resolved (which
may be accomplished by the relay itself), the following
actions occur:
• All protection functions of the relay will be blocked.
• Relay status contact 6A1-6A2-6A3 of the relay will
be
de
-
energized.
• The “Blocked” LED on the front panel will be lit.
If the problem persists, an event reporting the
particular problem is added to the Operational Log or
open fault log (see Table 12.1 on page 122).
This chapter describes the details and settings of the
self-monitoring features.
12.1 Self
-
Monitor Signal
Contact
Signal contact 5 of the relay is dedicated to reporting
the operational readiness of the relay. Event 51
(“
Relay OK
”) reports that the relay is operational with
at least one protection function active; and it is always
marshalled to relay status contact 6A1-6A2-6A3 (no
other event can be marshalled to that signal contact).
This contact is energized when the relay is ready to
operate.
12.2 Internal Self
-
Monitoring
The relay monitors its own internal components
(hardware and software).
12.2.1 Reset of LEDs
If the LED’s are reset, Event 5 is recorded in the
operational log. This does not affect the readiness of
the relay.
12.2.2 Change of Parameter Set
When changing which parameter set is active, or
when changes to the active set are being made
effective. For a brief time no set is active.
12.2.3 Software
-
Hardware
Mismatch
If on start-up the relay detects that its internal software
does not correspond to its hardware, event 100 and/or
101 will occur. The relay will not be ready.
12.2.4 Data Buffer Invalid or
Overflowing
If a data recording buffer becomes full and more data
is required to be written to the buffer, or if the relay
detects that the data in the buffer has been corrupted,
a corresponding event (115C) is reported in the
operational log or open fault log (depending on the
event). These events do not affect the readiness of
the relay.
12.2.5 Memory Monitoring
(Checksum)
A cyclic checksum is formed for the program memory
(EPROM), the parameter assignment memory
(EEPROM), and the working memory (RAM); then
compared to the stored checksum. If the checksum
does not match, event 135C occurs, and the relay will
not be ready until a subsequent cyclical checksum
does match, and event 135G occurs.
After settings to a parameter set are entered, the relay
performs a checksum of the parameter set. If the
checksum fails, the corresponding event (136C, 137C,
138C, or 139C) occurs. The corresponding going
event occurs when the same parameter set is entered
and no checksum error occurs. These events do not
affect the readiness of the relay unless the parameter
set in question (A, B, C, or D) is the active set.
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