i.
Current Input Signal
Warning! Read Safety Warning on Page 1
before attempting to use this control.
Note:
The Voltage/Current (VLT/CUR) jumper must be in “CUR”
position. Connect the negative current signal input to terminal “5”
and the positive to terminal “6.” The BC145 is factory calibrated so
that a 4 - 20mA signal will provide a 0 - 9 Volt output. The input
range can be converted to a 10 - 50mA range by attaching a 150Ω
1W resistor across the current input terminals “5” and “6.” See fig-
ure 3. Control must be recalibrated when the 150Ω resistor is installed. The range of signal
input can be changed to 1 - 5mA by removing resistor R3 from the printed circuit board.
Recalibrate the Signal Isolator to follow a 4 - 20mA current signal input as follows:
1.
Connect a 10V DC meter (digital DC meter is suggested) to terminals “9”(-) & “10” (+).
2.
Apply the minimum input current (4mA) at terminals “5” and “6.”
3.
Adjust the “MIN” trimpot to an output voltage of 0 volt DC.
4.
Set the input current to 20mA and adjust the “MAX” trimpot so that the output voltage is at
the desired level (9V DC).
5.
Repeat steps 3 and 4 if extreme accuracy is required. The Signal Isolator is now cali-
brated to provide 0 - 9V DC output with a 4 - 20mA input.
6.
Use the “MIN” and “MAX” trimpot if other than 0 - 9V DC output is required with the respec-
tive input current range.
6
5
6
150
Ω
Resistor
Converts 4 - 20mA
to 10 - 50mA
+
–
4 - 20mA
FIGURE 3 – CURRENT INPUT
SIGNAL CONNECTION
!
