ABB ETL600, Instruction Manual, Page: 117 / 382

ETL600 1KHW001489-EN
ABB Switzerland Ltd
It is possible to reset the counters individually or all at once via the
HMI600. Date and time of the last reset of each counter are recorded
in non-volatile memory as part of the system status.
The counter range before overflow is > 10
9
.
Note:
If external command counters are used, their counter
reading may differ from the internal command
counters due to different response times, especially
for short commands and if electromechanical
counters are used.
3.6.8.17. Alarms Sources
Self-testing routines continuously monitor the operational status of the
NSD600. In case the alarm source does not allow the safe reception of
a command, the outputs are blocked.
A list of alarm messages and their causes can be found in section
9.6
.
The alarm concept of the ETL600 including NSD600 is described in
section
9.3.1
.
The following criteria are continuously monitored and produce alarms
(the list is not final):
•
Guard signal level out of limits.
The guard signal level alarm is configurable from ± 3 to ± 12 dB
related to nominal guard level.
•
Signal-to-noise ratio low.
The SNR alarm threshold for all applications is 7 dB for alarm
pickup and 10 dB for release of the alarm. The SNR scale of the
alarm threshold is related to the nominal level of the test signal.
•
Cyclic loop test failure (> 3 attempts)
•
Tx single component failure (from relay interface; after > 1 second)
•
Rx single component failure (guard and tripping signals being
either received simultaneously or completely lost; after > 1 second)
•
Tx command duration (sending the guard signal, speech and the
disconnectable channels again after a predefined time; default 5
seconds)
•
Rx command duration, if configured (blocking the command
output(s) after a predefined time; default 5 seconds)
•
Checksum error (program memory failure; instantaneous ->
equipment will reboot automatically, an event recorder entry will be
added)
•
Rx command overload (from each FET output of the relay
interfaces; instantaneously)
•
System clock error
•
Power supply voltage low
Structure and Function November 2005 3-85