Impulse DSCA47 - Manual

High Performance Signal Conditioners DSCA
For information call 800-444-7644 154
DSCA47
Linearized Thermocouple Input Signal Conditioners
Description
Each DSCA47 thermocouple input module provides a single channel of thermocouple
input which is filtered, isolated, amplified, linearized, and converted to a high level
voltage output. Signal filtering is accomplished with a five-pole filter which provides 85dB
of normal-mode-rejection at 60Hz and 80dB at 50Hz. An anti-aliasing pole is located
on the field side of the isolation barrier, and the other four poles are on the system 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 DSCA47 can interface to eight industry standard thermocouple types: J, K, T, E,
R, S, B and N. Each module has cold junction compensation to correct for parasitic
thermocouples formed by the thermocouple wire and input screw terminals on the
module. Upscale open thermocouple detection is provided by internal circuitry.
Downscale indication can be implemented by installing a 47M Ω , ±20% resistor
between screw terminals 6 and 8 on the input terminal block.
Module output is either voltage or current. For current output models a dedicated
loop supply is provided at terminal 3 (+OUT) with loop return located at terminal 4 (-OUT).
The system-side load may be either floating or grounded.
Special input circuits provide protection against accidental connection of power-line
voltages up to 240VAC and against transient events as defined by ANSI/IEEE
C37.90.1. Protection circuits are also present on the signal output and power
input terminals to guard against transient events and power reversal. Power lines
are secured to the module using screw terminals which are in pluggable terminal
blocks for ease of system assembly and reconfiguration.
The modules have excellent stability over time and do not require recalibration,
however, zero and span settings are adjustable up to ±3% to accommodate
Figure 1: DSCA47 Block Diagram
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Features
• Interfaces to Types J, K, T, E, R, S, B, and N
Thermocouples
• Linearizes Thermocouple Signal
• Industry Standard Output of either 0-10V,
0-20mA, or 4-20mA
• 1500Vrms Transformer Isolation
• ANSI/IEEE C37.90.1 Transient Protection
• Input Protected to 240VAC Continuous
• True 3-Way Isolation
• Wide Range of Supply Voltage
• 160dB CMR
• 85dB NMR at 60Hz, 80dB at 50Hz
• ±0.08% Accuracy
• Easily Mounts on Standard DIN Rail
• C-UL-US Listed
• CE and ATEX Compliant
situations where fine-tuning is desired. The adjustments are made using potentiometers
located under the front panel label and are non-interactive for ease of use.