Impulse DSCT47 User Manual
DSCT47
Linearized Thermocouple Input Transmitters
Description
Each DSCT47 thermocouple input transmitter provides a single channel of
thermocouple input which is filtered, isolated, amplified, linearized, 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.
Linearization is achieved by creating a non-linear transfer function through the
module itself. This non-linear transfer function is configured at the factory and
is designed to be equal and opposite to the thermocouple non-linearity.
The DSCT47 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 DSCT47 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
DIN Rail Mount Two-WireTransmitters
DSCT
▲
Features
Interfaces to Types J, K, T, E, R, S, B, and N
Thermocouples
Linearizes Thermocouple Signal
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
±0.10% Accuracy
Easily Mounts on Standard DIN Rail
CSA and FM Approvals Pending
CE Compliant
span settings are adjustable up to ±3%. The adjustments are made using
potentiometers located under the front panel label and are non-interactive for
ease of use.
Figure 1: DSCT47 Block Diagram
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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 ±3% Zero and Span
Accuracy See Ordering Information
Stability
Offset ±60ppm/°C
Gain ±80ppm/°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
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.
Typical at TA=+25°C and +24V loop voltage
DSCT47
as per NIST monograph 175, ITS-90
Class A (Radiated, Conducted)
Class A (ESD, RF, EFT)
Ordering Information
TC
Model
Type
Input Range Accuracy
DSCT47J-01 J 0°C to +760°C ±0.1% span ±0.76°C
(+32°F to +1400°F)
DSCT47J-02 J -100°C to +300°C ±0.1% span ±0.40°C
(-148°F to +572°F)
DSCT47J-03 J 0°C to +500°C ±0.1% span ±0.50°C
(+32°F to +932°F)
DSCT47K-04 K 0°C to +1000°C ±0.1% span ±1.00°C
(+32°F to +1832°F)
DSCT47K-05 K 0°C to +500°C ±0.1% span ±0.50°C
(+32°F to +932°F)
DSCT47K-13 K -100°C to +1350°C ±0.1% span ±1.45°C
(-148°F to +2462°F)
DSCT47K-14 K 0°C to +1200°C ±0.1% span ±1.20°C
(32°F to +2192°F)
DSCT47T-06 T -100°C to +400°C ±0.1% span ±0.50°C
(-148°F to +752°F)
DSCT47T-07 T 0°C to +200°C ±0.1% span ±0.20°C
(+32°F to +392°F)
DSCT47E-08 E 0°C to +1000°C ±0.1% span ±1.00°C
(+32°F to +1832°F)
DSCT47R-09 R +500°C to +1750°C ±0.1% span ±1.25°C
(+932°F to +3182°F)
DSCT47S-10 S +500°C to +1750°C ±0.1% span ±1.25°C
(+932°F to +3182°F)
DSCT47B-11 B +500°C to +1800°C ±0.1% span ±1.30°C
(+932°F to +3272°F)
DSCT47N-15 N -100°C to +1300°C ±0.1% span ±1.40°C
(-148°F to +2372°F)
Thermocouple Alloy Combinations
Standards: DIN IEC 584, ANSI MC96-1-82, JIS C 1602-1981
Type Material
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%
Silicon- 0.1% Magnesium
(1)
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DSCT
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