Emerson 308014EN Water Heater User Manual


 
4-3
Rosemount Tank Radar REX
Chapter 4 The Data Acquisition Unit
Installation Manual
308014EN, Edition 4
May 2013
4.3 Connecting the Data Acquisition Unit, DAU 2100
Instructions for connection of the Data Acquisition Unit is given on the
inside of its cover.
4.3.1 Power Supply
The Data Acquisition Unit receives its power via the local line from the
associated Radar Tank Gauge. If the distance between the Transmitter
Head and the Data Acquisition Unit is longer than 2.0 m, a junction box
must be used to connect an extension cable. This extension cable must
not be longer than 50 m. For safety reasons the ends of the unused
wires must be properly insulated and terminated. The junction box can
either be customer supplied or supplied by Rosemount Tank Gauging as
an option, see chapter 8.
4.3.2 Temperature Sensors
Under the lid of the Data Acquisition Unit there are instructions printed as
to how to connect the sensors and transducers.
Figure 4-3. The X21 terminal for temperature sensor connec-
tions.
Either Pt 100 (spot element) or Cu 100 (averaging sensor) temperature
sensors can be used. If the sensors are connected with common return
wires then jumpers must be connected in the Data Acquisition Unit
terminals.
Intrinsically safe connection of the temperature sensors, the RTDs, is
made with n + 2 wires for an n-element spot or averaging sensor. There
are spot elements with three wires for each element. The DAUs can
connect up to 14 RTDs (Resistance Temperature Detectors) on the X21
terminal on the motherboard.
Connect Reference
Resistor to terminals
43, 44 and 45.
Connect
temperature
sensors.
DAU_Tempsens_Connect.eps