4230 Flow Meter
Section 4 Optional Equipment
4-5
4.3 4 to 20 mA (Analog)
Outputs
These outputs provide connection between a 4230 Flow Meter
and non-Isco process-control equipment, such as chlorinators, or
any other type of equipment that you can control with a 4-20 mil-
liampere current loop. Analog outputs convert digital infor-
mation from the flow meter to a variable analog output current
ranging from 4 to 20 milliamperes. When a condition measured
by the flow meter is converted into an analog output, 4 mA
becomes the 0% or baseline for the condition, while 20 mA
becomes the 100% or full-scale of the condition. Isco offers two
different arrangements for providing the 4-20 mA outputs. One
is an external box that converts the signals from the flow meter
to a 4-20 mA current loop. The other is an internal circuit board
containing from one to three separate analog output circuits on
the same board.
The 4 to 20 mA current is an industrial standard current loop for
process control equipment that must respond to changing condi-
tions by varying output rates.
4.3.1 External 4-20 mA
Output Interface
The external 4-20 mA Output Interface has its own case and
AC power supply. Commercial power (120 VAC) must be
available for this device. Battery operation (12 VDC) is not fea-
sible due to voltage and current demands. It comes with a line
cord, connectors, and two interconnect cables. One cable has
6-pin M/S connectors on both ends. This cable connects the input
of the 4-20 mA Output Interface to the flow meter Interrogator
connector. The other cable has a three-pin plug on it that con-
nects to the output connector of the 4-20 mA Output Interface.
This cable ends in three pigtailed wires you connect to the
equipment you want to control with the 4-20 mA Output
Interface.
Table 4-1 4-20 mA Output Interface:
Technical Specifications
Power 120 VAC
1
/8 Amp.
Output Connector 3-pin male plug
Pin A: + current out
Pin B: – current out
Pin C: not used
Output Accuracy
At 72° F (22°C)
Full Oper. Range
±0.25% of full-scale
±0.5% of full scale
Operating Range 0° to 140°F (–18° to 60°C)
Resolution 0.1% of full-scale
To Next Page
Loading...
