Reference Manual
00809-0100-4148, Rev BA
July 2010
3-3
Rosemount 148
Sensor Configuration
The following sensors indicate the sensor type and the number of wires to be
connected:
• 2-, 3-, or 4-wire Pt 100:
= 0.00385
/°C
• 2-, 3-, or 4-wire Pt 100:
= 0.003916
/°C
• 2-, 3-, or 4-wire Ni 120 nickel RTDs
• 2-, 3-, or 4-wire Cu 10 RTDs
• IEC/NIST/DIN Type B, J, K, N, R, S Thermocouples
• 2-, 3-, or 4-wire 0 - 2000 ohms
A complete line of temperature sensors, thermowells, and accessory
mounting hardware is available from Emerson Process Management.
Output Configuration
The Output Configuration area allows the user to set the desired
measurement values for the transmitter:
• Degrees Celsius
• Degrees Fahrenheit
• Degrees Rankine
• Kelvin
• Ohms
• Millivolts
The 4 mA and 20 mA measurement point will need to be set to determine the
analog output based on the temperature reading.
The Lower and Upper Range Limit of the sensor type selected above can also
be viewed.
Damping
The Damping value changes the response time of the transmitter to smooth
variations in the readings caused by rapid changes in input. Determine the
appropriate damping setting based on the necessary response time, signal
stability, and other requirements of the loop dynamics of the system. The
default damping value is 5.0 seconds and can be reset to any value between
0 and 32 seconds.
The value chosen for damping affects the response time of the transmitter.
When set to zero (or disabled), the damping function is off and the transmitter
output reacts to changes in input as quickly as the intermittent sensor
algorithm allows (refer to “*”) for a description of the intermittent sensor
algorithm. Increasing the damping value increases the transmitter response
time.
With damping enabled, the transmitter outputs values according to the
following relationship. At time t
Damping Value =
P
N
P
–
1
e
t
–
T
----
–
+
P =previous damped value
N =new sensor value
T = damping time constant
U =update rate