Impulse SCM5B32 User Manual

Scm5b32, Analog current input modules, Scm5b

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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

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

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