Siemens 7SR157 Argus, Manual

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7SR157 Technical Manual
Chapter 1 - Page 18 of 38 © 2022 Siemens Protection Devices Limited
2.10 Self Monitoring
The relay incorporates a number of self-monitoring features. Each of these features can initiate a controlled reset
recovery sequence.
Supervision includes a power supply watchdog, code execution watchdog, memory checks by checksum and
processor/ADC health checks. When all checks indicate the relay is operating correctly the ‘Prot. Healthy’ LED is
illuminated.
If an internal failure is detected, a message will be displayed. The relay will reset in an attempt to rectify the
failure. This will result in de-energisation of any binary output mapped to ‘Prot. Healthy’ and flashing of the ‘Prot.
Healthy’ LED. If a successful reset is achieved by the relay the LED and output contact will revert back to normal
operational mode, and the relay will restart, therefore ensuring the circuit is protected for the maximum time.
Figure 2.13 shows the events which are generated when the relay re-starts. The highlighted events show the
cause of the re-start. The event which comes next shows the type of restart followed by the relay: Warm, Cold or
Re-Start.
As a further safeguard, if the Relay performs a number of unexpected starts SYSTEM CONFIG> Unexpected
Restart Count in a given time SYSTEM CONFIG> Unexpected Restart Period , it can be configured using the
SYSTEM CONFIG> Unexpected Restart Blocking setting to remove itself from service. In this case the Relay
will display an error message:
--------------------
|UNEXPECTED RESTART |
|COUNTS EXCEEDED! |
|DEVICE LOCKED OUT |
| |
--------------------
Figure 2-11 Unexpected Restarts Lockout Text
And enter a locked-up mode. In this mode the Relay will disable operation of all LED’s and Binary Outputs,
including Protection Healthy, all pushbuttons and any data communications.
Once the Relay has failed in this manner, it is non-recoverable at site and must be returned to the manufacturer
for repair.
A meter, Miscellaneous Meters>Unexpected Restarts, is provided to show how many Unexpected Restarts have
occurred during the previous Unexpected Restart Period. This is resettable from the front fascia.