Handling Faults; Primary Return Temperature (B7); Measurement; Multipurpose Temperature Sensor (B71) - Siemens RVD110 Basic Documentation

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4.5.2

Handling faults

If there is a fault in the sensor's measuring circuit (short-circuit or open-circuit), a fault
status message will be generated.
The d.h.w. charging pump or the diverting valve will be deactivated and, in the case of
instantaneous d.h.w. heating systems, the respective valve shut. When interrogating the
d.h.w. temperature on the QAW70 room unit, its display will show --- if there is a short-
circuit or open-circuit.
4.6

Primary return temperature (B7)

4.6.1

Measurement

This measured value is required for minimum and maximum limitation of the primary
return temperature and for DRT limitation.
The following types of sensors can be used:
• Strap-on temperature sensor QAD22 or immersion temperature sensor QAE22...
(sensing element LG-Ni 1000 Ω at 0 °C)
• Commercially available immersion temperature sensors with a sensing element
Pt 500 Ω at 0 °C
The controller automatically identifies the type of sensor used.
The range of use of all types of sensors is 0...140 °C. The Pt sensors can be used for
fluid temperatures up to180 °C.
4.6.2 Handling faults
If the primary return temperature sensor becomes faulty (short-circuit or open-circuit), a
fault status message will be generated as soon as maximum limitation of the return
temperature or DRT limitation has become active. In that case, the controller's LCD will
display Er.
4.7

Multipurpose temperature sensor (B71)

4.7.1

Use and measurement

Depending on the type of plant and the configuration, the multipurpose temperature
sensor is used as a
• secondary return temperature sensor
• d.h.w. temperature sensor
• heating circuit flow temperature sensor
The sensor acquires the temperature with a sensing element LG-Ni 1000
Available are the strap-on temperature sensor QAD22 and the immersion temperature
sensor QAE22... with a measuring range of 0...140 °C.
4.7.2 Handling faults
• When used as a secondary return temperature sensor:
If there is a fault in the sensor's measuring circuit (short-circuit or open-circuit), a
fault status message will be generated when DRT limitation is activated. In that case,
the controller's LCD will display Er
• When used as d.h.w. temperature sensor:
If there is a fault in the sensor's measuring circuit (short-circuit or open-circuit), a
Basic Documentation RVD110, RVD130
4 Acquisition of the measured values
CE1P2381E
27.05.2004