Impulse DSCA34 - Manual

High Performance Signal Conditioners DSCA
For information call 800-444-7644 136
DSCA34
Linearized 2- or 3-Wire RTD Input Signal Conditioners
Description
Each DSCA34 RTD input module provides a single channel of RTD 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.
RTD excitation is provided from the module using a precision current source.
Lead compensation is achieved by matching two current paths which cancels
the effects of lead resistance. The excitation current is small ( approx. 0.25mA)
which minimizes self-heating of the RTD.
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.
Signal and 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
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.
Figure 1: DSCA34 Block Diagram
Features
• Interfaces to 100 Ω Platinum or 120 Ω
Nickel RTDs
• Linearizes RTD 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
• ±0.025% Conformity
• Easily Mounts on Standard DIN Rail
• C-UL-US Listed
• CE and ATEX Compliant
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