45/171
Siemens Building Technologies
Basic Documentation LMU54... / LMU64...
CC1P7494en
HVAC Products
3 Functions
07.11.2002
When defining the minimum and maximum heat output, the «Speed limitation» function
is of importance. This function is selected via parameterization:
KonfigRg5.2 = 0:
Without speed limitation
KonfigRg5.2 = 1:
With speed limitation
•
Without speed limitation
In that case, the limit values selected for the setting range of heat output are the PWM
control values of the fan.
Supply voltage variations have an impact on the heat output and the fan will not catch
up. The maximum heat output or the modulating range can be determined with the help
of the following graph, depending on the type of plant components connected:
Heat output
(control of fan)
Output signal of
temperature controller
7494d01E
LmodVL
Max. heat output without RU
Max. heat output with RU
100 %
Modulating range with RU
Modulating range without RU
Modulating range d.h.w.
Max. modulating range
LmodTL
Modulating range of the LMU... without speed limitation
The output limits in the case of heat demand are dependent on the connection of a RU.
The following table shows the assignment:
RU
Maximum heat output PhzMaxAkt
Present
See calculations below
Not present
PhzMax
Formula to be used for weather compensation without room influence via the RU:
RelModLevSet
PhzMaxAkt =
•
(PhzMax – LmodTL) + LmodTL
100 %
RelModLevSet:
The relative modulation level setting specifies the maximum degree
of modulation of the RU in % of the modulating range.
Load limitation
