Impulse SCM5B32 - Manual

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Isolated Analog Signal Conditioning Products SCM5B
SCM5B32
Analog Current Input Modules
Description
Each SCM5B32 current input module provides a single channel of analog input
which is filtered, isolated, amplified, and converted to a high level analog voltage
output (Figure 1). This voltage output is logic switch controlled, which allows
these modules to share a common analog bus without the requirement of
external multiplexers.
The SCM5B modules are designed with a completely isolated computer side
circuit which can be floated to ±50V from Power Common, pin 16. This complete
isolation means that no connection is required between I/O Common and
Power Common for proper operation of the output switch. If desired, the
output switch can be turned on continuously by simply connecting pin 22, the
Read-Enable pin, to I/O Common, pin 19.
A precision 20
Ω current conversion resistor is supplied with the SCM5B32
module. Sockets are provided on the SCMPB01/02/03/04/05/06/07 backpanels
to allow installation of this resistor. Extra resistors are available under part
number SCMXR1.
Signal filtering is accomplished with a six-pole filter which provides 95dB of
normal-mode rejection at 60Hz and 90dB at 50Hz. Two poles of this filter
are on the field side of the isolation barrier, and the other four are on the
computer side.
After the initial field-side filtering, the input signal is chopped by a proprietary
chopper circuit. Isolation is provided by transformer coupling, again using a
proprietary technique to suppress transmission of common mode spikes or
surges. The module is powered from +5VDC, ±5%.
A special input circuit on the SCM5B32 modules provides protection against
accidental connection of power-line voltages up to 240VAC.
Figure 1: SCM5B32 Block Diagram
▲
Features
• Accepts Milliamp Level Signals
• High Level Voltage Outputs
• 1500Vrms Transformer Isolation
• ANSI/IEEE C37.90.1 Transient Protection
• Input Protected to 240VAC Continuous
• 160dB CMR
• 95dB NMR at 60Hz, 90dB at 50Hz
• ±0.03% Accuracy
• ±0.005% Linearity
• CSA Certified, FM Approved, CE and ATEX
Compliant
• Mix and Match SCM5B Types on Backpanel