Self Monitoring; Figure 2-11 Start-Up Counter Meter; Figure 2-12 Unexpected Restarts Lockout Text - Siemens 7SR105 Rho User Manual

Motor resistance temperature detectors (RTDs) can be connected via temperature inputs. Up to six RTD sensors
can be monitored. Provision to configure seven types of RTD inputs (for 3 wire configuration). Temperature
inputs can be configurable for RTD Alarm and Trip application.

2.12 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 'Protection 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 'protection healthy' and flashing of the
protection 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.
A start-up counter meter is provided to display the number of start-ups the relay has performed. Once the number
of start-ups has exceeded a set number, an alarm output can be given.
Reset of the counter can be done from the meter or via a binary input or a command.
Various types of start-up are monitored by the relay:
1. power-on starts
expected starts (user initiated via communications)
2.
3. unexpected starts (caused by the relay watchdog)
Any combination of these can be selected for the start-up count. This is done in the MAINTENANCE MENU >
START COUNT menu using the Start Types setting. All the start-up types selected (ticked) will be added to the
overall start-up count.
The number of restarts before the alarm output is raised is set in the MAINTENANCE MENU > START COUNT
menu using the Start Count Target setting.
When the number of relay start-ups reaches the target value an output is raised, OUTPUT MATRIX > Start
Count Alarm, which can be programmed to any combination of binary outputs, LED's or virtual outputs.
The following screen-shot show the events which are generated when the relay restarts. 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:
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.
©2018 Siemens Protection Devices

Figure 2-11 Start-up Counter Meter

|UNEXPECTED RESTART
|COUNTS EXCEEDED!
|DEVICE LOCKED OUT
|
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Figure 2-12 Unexpected Restarts Lockout Text

7SR105 Rho Description of Operation
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Chapter 1 Page 20 of 57