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Impulse DSCT30_31 User Manual

Dsct30/31, Analog voltage input transmitters, Dsct

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DIN Rail Mount Two-WireTransmitters

DSCT

For information call 800-444-7644

200

DSCT30/31

Analog Voltage Input Transmitters

Figure 1: DSCT30/31 Block Diagram

Features

• Accepts Millivolt and Voltage Level Signals
• Process Current Output
• 1500Vrms Transformer Isolation
• ANSI/IEEE C37.90.1 Transient Protection
• Input and Output Protected to 240VAC

Continuous

• Up to 60V Loop Voltage
• 160dB CMR
• 85dB NMR at 60Hz, 80dB at 50Hz
• ±0.03% Accuracy
• ±0.01% Linearity
• Easily Mounts on Standard DIN Rail
• CSA and FM Approvals Pending
• CE Compliant

Description

Each DSCT30 and DSCT31 voltage input transmitter provides a single channel

of analog input which is filtered, isolated, amplified, and converted to a process

current output (Figure 1). 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 are on the process loop 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 trans-

mission of common mode spikes or surges.
Special input and output circuits on the DSCT30 and DSCT31 transmitters

provide protection against accidental connection of power-line voltages up to

240VAC and against transient events as defined by ANSI/IEEE C37.90.1.

Signal and loop 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 ±10% 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.