Impulse DSCT37 User Manual

DSCT37

Thermocouple Input Transmitters

Description

Each DSCT37 thermocouple input transmitter provides a single channel of

thermocouple 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 transmission of common mode spikes or surges.

The DSCT37 can interface to eight industry standard thermocouple types:

J, K, T, E, R, S, B and N. Each transmitter is cold-junction compensated to

correct for parasitic thermocouples formed by the thermocouple wire and

screw terminals on the transmitter. Upscale open thermocouple detection is

provided by circuitry. Downscale indication can be implemented by installing

a 47MΩ, ±20% resistor between screw terminals 6 (+IN) and 8 (-EXC) on the

input terminal block.

Special input and output circuits on the DSCT37 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. Loop power lines are

secured to the module using screw terminals, which are in pluggable terminal

blocks for ease of system assembly and reconfiguration. Transmitter zero and

span settings are adjustable up to ±10%. The adjustments are made using

potentiometers located under the front panel label and are non-interactive for

ease of use.

DIN Rail Mount Two-WireTransmitters

▲

Features

 Interfaces to Types J, K, T, E, R, S, B, and N

Thermocouples

 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

 ±0.05% Accuracy

 ±0.01% Linearity

 Easily Mounts on Standard DIN Rail

 CSA and FM Approvals Pending

 CE Compliant

DSCT

Figure 1: DSCT37 Block Diagram

208

For information call 800-444-7644

DIN Rail Mount Two-Wire Transmitters

DSCT

Specifications

Module

Input Range Standard thermocouple temperature limits

Input Bias Current -25nA

Input Resistance

Normal 50MΩ
Power Off 66kΩ
Overload 66kΩ

Input Protection

Continuous 240Vrms max

Transient ANSI/IEEE C37.90.1

CMV, Input to Output

Continuous 1500Vrms max

Transient ANSI/IEEE C37.90.1

CMR (50Hz or 60Hz) 160dB

NMR 85dB at 60Hz, 80dB at 50Hz

Adjustability ±10% Zero and Span

Accuracy See Ordering Information

Stability

Offset ±40ppm/°C

Gain ±60ppm/°C

Cold Junction Compensation

Accuracy, +25°C ±0.25°C

Accuracy, 0°C to +50°C ±0.50°C

Accuracy, -40°C to +80°C ±1.25°C

Open Input Response Upscale

Open Input Detection Time < 5s

Noise

Output, 100kHz 3µArms

Bandwidth, 3dB 3Hz

Response Time, 90% Span 165ms

Output Range 4mA to 20mA

Output Limits

Under-range 2.8mA

Over-range 29mA

Output Protection

Reverse Polarity Continuous

Over-voltage 240Vrms Continuous

Transient ANSI/IEEE C37.90.1

Loop Supply Voltage 10.8V to 60V

Loop Supply Sensitivity ±0.0005%/V

Turn-On Delay 400ms

Typical at TA=+25°C and +24V loop voltage

DSCT37

as per NIST monograph 175, ITS-90

Ordering Information

TC

Model

Type



Input Range Accuracy

DSCT37J-01 J -100°C to +760°C ±0.05% ±0.43°C

(-148°F to +1400°F)

DSCT37K-02 K -100°C to +1350°C ±0.05% ±0.73°C

(-148°F to +2462°F)

DSCT37T-03 T -100°C to +400°C ±0.05% ±0.25°C

(-148°F to +752°F)

DSCT37E-04 E 0°C to +900°C ±0.05% ±0.45°C

(+32°F to +1652°F)

DSCT37R-05 R 0°C to +1750°C ±0.05% ±0.88°C

(+32°F to +3182°F)

DSCT37S-06 S 0°C to +1750°C ±0.05% ±0.88°C

(+32°F to +3182°F)

DSCT37B-07 B 0°C to +1800°C ±0.05% ±0.90°C

(+32°F to +3272°F)

DSCT37N-08 N -100°C to +1300°C ±0.05% ±0.70°C

(-148°F to +2372°F)



Thermocouple Alloy Combinations

Standards: DIN IEC 584, ANSI MC96-1-82, JIS C 1602-1981

Type

J Iron vs. Copper-Nickel
K Nickel-Chromium vs. Nickel-Aluminum
T Copper vs. Copper-Nickel
E Nickel-Chromium vs. Copper-Nickel
R Platinum-13% Rhodium vs. Platinum
S Platinum-10% Rhodium vs. Platinum
B Platinum-30% Rhodium vs. Platinum-6% Rhodium
N Nickel-14.2% Chromium-1.4% Silicon vs. Nickel-4.4%

Material

Silicon- 0.1% Magnesium

(1)

Environmental

Operating Temp. Range 40°C to +80°C

Storage Temp. Range 40°C to +80°C

Relative Humidity 0 to 95% Noncondensing

Emissions EN50081-1, ISM Group 1,

Immunity EN50082-1, ISM Group 1,

Mechanical Dimensions 2.95" x 0.89" x 4.13

(h)(w)(d) (75mm x 22.5mm x 105mm)

Mounting DIN EN 50022 35x7.5 or 35x15 rail

NOTES:

(1) Includes conformity, hysteresis, repeatability and CJC error.

Class A (Radiated, Conducted)

Class A (ESD, RF, EFT)

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DSCT

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