Dynamic Supervision - Siemens LMU54 Series Basic Documentation

Dynamic supervision

Function
Note
44/171
Siemens Building Technologies
HVAC Products
When a heating circuit pump is activated, the pressure downstream from the pump will
increase and the pressure upstream will decrease. These changes in pressure depend
on the pumping power and the pump's capacity.
The pressure sensor acquires the pressure before and after the pump is switched on.
The pressure differential must exceed a minimum threshold (dpH2OminPuOn) to ensure
proper functioning of the pump.
At the same time, the same pressure differential may not exceed a maximum threshold
(dpH2OmaxPuOn), which could lead to the indication of too little circulation or no
circulation at all.
If this criterion is not met, start of the pump will be prevented for 10 minutes, with
indication of the relevant signal code. If start prevention takes place 6 times in
successive order, lockout will be triggered if activated via parameter «KonfigRg5.7=1».
If the pump continues to run during start prevention, it will be locked for the last 10
seconds of start prevention, to be able to again acquire the pressure change caused by
the reactivation of the pump, after the boiler has been released again.
The pressure thresholds can be parameterized in the range from 0 to 5 bar, the
resolution being 0.02 bar. Checking of the pressure thresholds is individually switched
off by selecting 0 bar as the minimum value and 5 bar as the maximum value.
Parameter bit «KonfigRg4.3» can be used to define whether a pressure increase or
decrease will be expected after the pump is switched on.
If a diagram was configured without a pump Q1, the function must be deactivated.
The differential pressure is checked 8 seconds after the pump was switched on. Then,
during normal pump operation, the differential pressure will no longer be checked.
If a configuration with water pressure sensor was selected (KonfigRg3) and supervision
of water circulation has been released (dpH2Omin/maxPuOn), the LMU... must read a
valid value for the water pressure. Otherwise, there will be start prevention with the
relevant signal code or lockout will be triggered (KonfigRg5.7).
dpH2OmaxPuOn
dpH2OminPuOn
Pump off
T0
Dynamic water pressure supervision of the LMU...
Basic Documentation LMU54... / LMU64...
3 Functions
Valid pressure range
after pumpe on
∆ P
(e.g. 0.4 bar)
Pump on
T1 T1+8 s
Pump off
T2
Time
CC1P7494en
07.11.2002