Models 375-31H Area Monitor with Neutron Detector
Section 5
Ludlum Measurements, Inc.
Page 5-9
January 2021
For Series One:
Decade
“Base” Display
mA Value
0
0.01
4 mA
1
0.10
7.2 mA
2
1.00
10.4 mA
3
10.00
13.6 mA
4
100
16.8 mA
5
1000
20 mA
mA value =
4 𝑚𝐴 + (3.2 𝑚𝐴 ∗ Decade) + 3.2 log (
𝑑𝑖𝑠𝑝𝑙𝑎𝑦 𝑟𝑒𝑎𝑑𝑖𝑛𝑔
𝑏𝑎𝑠𝑒
)
Display reading =
10
𝑚𝐴 𝑣𝑎𝑙𝑢𝑒−4−(3.2∗𝑑𝑒𝑐𝑎𝑑𝑒)
3.2
∗ 𝑏𝑎𝑠𝑒
Note:
For the Model 375 Series One (that displays values to two decimal
places), the 4-20 mA output starts a decade lower, from 0.01 to 0.1 units,
with the highest decade being 100 to 1000 units. The full-scale output of
20 mA can be adjusted for a reading of 1000 units. The highest displayed
range of 1000 to 10,000 units then has a constant 20 mA output.
SPECIFICATIONS
Power Required
: 7.5 Vdc at 100 mA; minimum V
in
= 5.5 V and
maximum V
in
= 15 V (connected internally)
Terminating Resistor
: 250 ohm
Model 375 4 to 20 mA Isolated Output Connections (3-pin Hirose
connector)
Pin 1 is black (negative).
Pin 2 is white (positive).
