Static Supervision - Siemens LMU54 Series Basic Documentation

Static supervision

Function
Siemens Building Technologies
HVAC Products
If the pressure sensor is configured, the pressure switch or flow switch will no longer be
checked because water pressure supervision has the higher priority.
Water pressure supervision is overriding boiler temperature control.
When certain threshold values are crossed, the LMU... responds in one of the following
ways:
• Shutdown (PH2Omax), or
• Output reduction (PH2Omin), or
• Shutting down of boiler and pump (PH2OAbschalt)
If water pressure is too high or too low, there will either be start prevention or the unit
will initiate lockout, depending on the parameterization (KonfigRg5).
When water pressure returns to the permitted pressure range, the boiler will be released
with no delay. The following graph shows the various phases of water pressure
supervision:
Ph2o
PH2Omax
SdPH2O
SdPH2O
PH2Omin
PH2OAbschalt
Response =
None Shutdown
T0 T1
Static water pressure supervision with the LMU...
• Boiler shutdown will be triggered when:
• Boiler output limitation will be triggered when:
• Boiler and pump shutdown will be triggered when:
• Boiler output limitation or shutdown will be canceled when: Ph2o < PH2Omax – SdPH2O
If water pressure supervision responds, an error code or lockout code will be displayed.
To ensure that short-time crossings of the water pressure thresholds do not immediately
give rise to a response, the acquired water pressure will be filtered (τ ≈ 2 seconds).
Basic Documentation LMU54... / LMU64...
3 Functions
* Boiler
None output - 20 % None
T2 T3 T4 T5
Shutdown
* and pump off None
T6 T7
Time
Ph2o ≥ PH2Omax
Ph2o ≤ PH2Omin
Ph2o ≤ PH2OAbschalt
Ph2o > PH2Omin + SdPH2O
CC1P7494en
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07.11.2002