Siemens LMV5 Series Basic Documentation page 255

Siemens Building Technologies
HVAC Products
18.6 Self-test
During the startup phase and during operation, the system performs a number of self-
tests to ensure that the O
18.6.1 Sensor test
To detect aging O
2 sensors, a sensor test is made
identified by its increased internal resistance. The cell is considered too old when the
internal resistance measured is Ri < 5 Ω or Ri > 150 Ω.
The test is made at 23-hour intervals. To perform the test, a constant O2 value is
essential. This requirement is satisfied after prepurging or when a stationary load point
is reached. The system performs the test after 23 hours as soon as such stationary
values are available. If this is not the case after 24 hours, the load will be "frozen" in
operation so that the test can be made. If the system is in standby mode, the test will
be performed during the next startup phase (maximum 3 repetitions).
If the test is negative, the system's response will be one of the following, depending on
the parameter setting of «O2Ctrl/Guard»:
Parameter:
O Ctrl/Guard (auto deact / man deact / O
2
conAutoDeact)
man deact O trim controller and O
2
(auto deact): be made.
O / O O trim controller / O
2-guard 2- 2
safety shutdown will take place, followed by a repetition if possible,
control:
otherwise lockout.
conAutoDeact: Both the O
test is negative, O
be started up without O
Basic Documentation LMV51...
18 Addendum 4: LMV52... with O2 trim control and O2 module
sensor is working correctly.
2
. An aged measuring cell can be
monitor are deactivated. No sensor test will
2
monitor is / are activated. If the test is negative,
2
trim controller and the O
2
trim control will be deactivated and the burner will
2
trim control.
2
-guard/ O -control /
2 2
monitor are activated. If the
2
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01.10.2003