Watlow Controls 8LS, User Manual

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Installation
8LS User’s Guide 21
Source Impedance
Each sensor has a certain output impedance which is effectively
connected across the 8LS input amplifier when a measurement is made.
To reach the rated accuracy, the maximum source impedance should not
exceed 500 ohms. Consult Watlow Anafaze for operation with higher
source impedance.
Input Scaling
The 8LS contains an area that can be used to install resistors to scale
input voltages and convert milliamp inputs to match the -10 to 60mv (-
16.7% to 100%) input range. The input circuit is designed to enable
connection of current inputs (such as 4 to 20ma), voltage inputs, and 3-
Wire RTD. Watlow Anafaze will supply input scaling as needed -- order
option 8LS-SI-XX. The input circuit is shown below:
Ana In + = Analog input
Ana In - = Analog signal - input
Ana Gnd = Analog signal ground
RA is shorted by a jumper on the PC board, REMOVE THIS JUMPER
TO INSTALL RA.
Resistors should be 0.1% metal film, 1/4 watt. Note that the resistors
must be stood on end due to the compact size of the unit. Other
components such as capacitors can be installed for signal conditioning.
Please consult Watlow Anafaze. The PC board silk screen shows the
resistor locations.
Ana Gnd
Ana In -
RA
Analog Ground
RD
Ana In
+
RB Alternate
+
IN
- IN
Measurement
Input
RC
RB
+10 Vdc Reference
Terminal
Block