Gas Shortage Program; Sequence Diagram; Part Load Shutdown - Siemens LMV51 Series Basic Documentation

Gas shortage program

Sequence diagram

Part load shutdown

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HVAC Products
When gas pressure is insufficient (input PSmin-gas), the LMV5... ensures that a select-
able number of start attempts will be made while observing a selectable waiting time.
The waiting time between the start attempts is automatically doubled (based on the
value parameterized for the first waiting time).
The basic time is «DelayLackGas».
Parameter:
DelayLackGas
If, with the last of the parameterized start attempts, there is still a shortage of gas, the
burner control will initiate lockout.
Parameter:
StartPrev
Start conditions must be satisfied.
n = Limitation of the number of start repetitions (StartPrev). Example: 10
tDelay_G = Delay time gas shortage program (DelayLackGas). Example: 10 s
Phase 12 21
PSmin-Gas
tmax2
(e.g. 60 s)
Test repetition counter
< n
8. tDelay_G 12
10 s x 2 tmax2
7
= 1280 s Test repetition counter
< n
- Repetition counter will be reset after controlled shutdown
- When phase 22 is reached for the first time, delay time
will be reset to the selected parameter value
To prevent the boiler from shutting down when operating at high-fire, FARC will first
change to low-fire when there is no more demand from the controller.
Only then will the valves be closed.
The maximum time «MaxTmeLowFire» for changing to low-fire operation can be pa-
rameterized.
If the time is set to 0.2 seconds, part load shutdown will be deactivated.
Parameter:
MaxTmeLowFire
Basic Documentation LMV5...
4 Burner control
10 1. tDelay_G 12
10 s tmax2
Test repetition counter
< n
21 10 9. tDelay_G 12
10 s x 2
8
= 2560 s
Signal «OFF»
Signal «ON»
21 10 2. tDelay_G
10 s x 2
= 20 s
21 01
tmax2
Test repetition counter
= n = 10
CC1P7550en
13.08.2004
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