Impulse SCM7B36 - Manual

Isolated Process Control Signal Conditioning Products SCM7B
For information call 800-444-7644 76
SCM7B36
Isolated Potentiometer Input Modules
Description
Each SCM7B36 Potentiometer input module provides a single channel of
resistance input which is filtered, isolated, amplified, and converted to a high level
analog voltage output.
The SCM7B36 module interfaces to slidewires and potentiometers in both two
or three wire configuration and incorporates a five-pole filtering approach to
maximize both time and frequency response by taking advantage of both Bessel
and Butterworth characteristics. One pole of the filter is on the field side of the
isolation barrier; four are on the process control system side. In the 3-Wire
configuration, lead resistance compensation is provided if the resistance of the
“x” lead is closely equivalent to that of the “+” lead. Internal to the module,
measurement error due to lead resistance is canceled.
In response to the low level current excitation, and after initial field-side filtering,
the input signal is chopped by a proprietary chopper circuit and transferred
across the transformer isolation barrier, suppressing transmission of common
mode spikes and surges. The signal is then reconstructed and filtered for
process control system output.
Six standard input resistance ranges are offered, from 100
Ω to 10k Ω , with three
output ranges available: 0-5V, 1-5V, and 0-10V. Modules accept a wide 14-
35VDC power supply range (+24VDC nominal). Their compact packages
(2.13" x 1.705" x 0.605" max.) save space and are ideal for high channel
density applications. They are designed for easy DIN rail mounting using any
of Dataforth’s “-DIN” backpanels.
Figure 1: SCM7B36 Block Diagram
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Features
• Industry’s First 7B Potentiometer Input
Module
• Interfaces 100 Ω to 10k Ω Potentiometers
• High Level Voltage Outputs
• 1500Vrms Transformer Isolation
• Accuracy, ±0.03% of Span Typical,
±0.1% Max
• ANSI/IEEE C37.90.1 Transient Protection
• Input Protected to 120Vrms Continuous
• CSA Certified, FM Approved
• CE and ATEX Compliant