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Siemens Building Technologies Basic Documentation LMV51... CC1P7550en
HVAC Products 4 Burner control 01.10.2003
4.2.3 Special functions during the program sequence
The safety loop relays are deenergized, the alarm relay is activated and lockout will be
initiated, that is, Phase 00 can only be quit via manual reset.
Phase 00 is unlimited in terms of time.
During the lockout phase, the fan motor remains switched off if it was already
deactivated in the safety phase. Otherwise, postpurging takes place in the lockout
phase for a period of time that can be parameterized.
Parameter: PostpurgeLockout
The safety phase is an intermediate phase that is completed before lockout occurs. The
safety loop relays are deenergized, but lockout will not yet occur. The alarm relay is not
yet energized.
In the safety phase, the fan motor maintains the status of the previous phase, that is, it
remains switched on if it was on before, and it remains switched off if it was off before.
If possible or permitted, safety checks or repetition counter checks will be made. Their
results will decide on the transition to either «Lockout phase» or «Standby».
The duration of the safety phase varies (depending on the scope of testing), but lasts a
maximum of 30 seconds.
This procedure serves primarily for suppressing undesired lockouts, caused by EMC
effects, for instance.
There are 2 choices to reset the system:
1. Resetting on the AZL5…
If the burner control is in the lockout position, a reset produces the following reactions:
− The alarm relay will be deenergized and lockout indication switched off
− The lockout position will be cancelled
The function is only available when the unit is not in the lockout position.
The system can be manually locked by simultaneously pressing the ENTER and ESC
buttons on the AZL5… .
This function enables the user to stop the system during programming should an
emergency situation occur.
2. Resetting with the button on connection terminal «Reset» of the LMV5... basic unit
If the burner control is in the lockout position, a reset produces the following reactions:
− The alarm relay will be deenergized and lockout indication switched off
− The lockout position will be cancelled
If the burner control is not in the lockout position, a change to the lockout position will
take place when pressing the reset button.
If this reaction is not desired, it is possible to feed power to the reset button from the
alarm output, thus obtaining the same reaction as described in 1. above.
Lockout phase
(Phase 00)
Safety phase
(Phase 01)
Reset / manual lockout
Characteristics
Characteristics
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