CE1P2522E / 30.03.2000
Basic Documentation RVL470
Siemens Building Technologies
12/68
Acquisition of measured values
Landis & Staefa Division
4.1.5. Secondary return temperature (B71)
4.1.5.1. Measurement
The secondary return temperature is acquired with a sensor having a sensing element
LG-Ni 1000
Ω
at 0 °C. This measured value is required for limitation of the temperature
differential (DRT limitation) (plant types 3 and 6), together with the primary return tem-
perature.
4.1.5.2. Handling of faults
If there is a short-circuit or open-circuit in the measuring circuit, and if the controller re-
quires the return temperature, DRT limitation will be deactivated and a fault status mes-
sage generated.