7/17
Building Technologies Division User Manual LMV5... CC1A7550.5en
COx supervision and control 07.07.2015
4.5.1 COx Alarm operating mode
For straightforward supervision of the COx value, the parameter OptgMode COx must
be set to COx Alarm.
Phases of COx alarm:
Once prepurging is complete (upon entering phase 36), a single check is
performed to determine whether a COx signal is present.
If a COx signal is present, the fault response takes place immediately.
In the operating phases (60, 62), checks are performed continuously to determine
whether a COx signal is present after a waiting time has elapsed
(NumberTauSuspend * Tau Low-Fire).
If the COx signal is then present for longer than the parameterizable time COx
Alarm, the fault response takes place.
Fault response:
A safety shutdown is performed with a new startup and, depending on the O2 trim
controller repetition counter, lockout takes place.
Parameters:
The waiting time referred to above for the COx Alarm is dependent on the Tau
Low-Fire time constant determined by O2 trim control, and can be set using the
NumberTauSuspend parameter as a multiple of Tau Low-Fire:
Parameter NumberTauSuspend (0..140) * Tau Low-Fire)
Permissible time for a COx signal to reach in the operating phases (60 and 62)
before the fault response takes place:
Parameter Time COx Alarm (0..600s)
Note!
If prepurging is skipped, the COx value is not checked in this section of the
startup process.
Note!
The NumberTauSuspend parameter is also used as the locking time for O2 trim
control.
Note!
The sampling time of the COx signal is approximately 3 seconds.
This must be taken into account when setting the test time Time COx Alarm e.g.,
for a required maximum response time of 10 seconds, the parameter must be set
to 7 seconds.
Warning!
As the connections of the COx sensor to the LMV52.4, and the COx
functions in the LMV52.4, are not established in a fail-safe manner, use the
COx supervisory function always in conjunction with the O2 alarm function.
To Next Page
Loading...
