INVUE ELECTRONIC FLOWMETER, MODEL NT4400
9
Entegris, Inc. | User Guide
Load Resistance
If a load resistor, R
Load
, is used in
series with the current output (flow
and pressure outputs), the value of
R
Load
is dependent on the supply
voltage and the meter resistance and
is calculated from the following
formula.
where:
R
Load
= maximum load resistance
V
PS
= power supply voltage
R
meter
= meter resistance
(theoretically = 0)
If R
Load
is calculated using a voltage
drop across the meter (V
m
), the
following equation is used:
R
Load
= 50 * (V
PS
- 12
- V
m
)
Figure 4 below shows the power
required for a 4 –20 mA loop.
(V
PS
- 12)
R
Load
=
0.02
- R
meter
800
600
0
12
Power Supply Voltage
(V
PS
)
R
Load
(Ohms)
24
28
Operating
region
Figure 4. Power required for a 4 – 12 mA loop.