Impulse SCM7B37 User Manual

Isolated Process Control Signal Conditioning Products

SCM7B37

Isolated Thermocouple Input Modules

Description

SCM7B37 modules accept a single channel of input from Type J, K, T, E, R,

S, or B thermocouples. The signal is filtered, isolated, amplified, and converted

to a high level analog voltage for output to the process control system

(Figure 1).

Cold junction compensation (CJC) is performed using an NTC thermistor (see

Additional SCM7B Part Numbers section for P/N and AN701 for further

information) externally mounted under the field-side terminal block on the

backpanel (Figure 1). Open thermocouple detection is upscale using a 30nA

current source in the input circuitry.

These modules incorporate a five-pole filtering approach to maximize both time

and frequency response by taking advantage of both Thomson (Bessel) and

Butterworth characteristics. One pole of the filter is on the field side of the isolation

barrier; four are on the process control system side.

After the initial field-side filtering, the input signal is chopped by a proprietary

chopper circuit and transferred across the transformer isolation barrier,

suppressing transmission of common mode spikes and surges. The signal is

then reconstructed and filtered for process control system output.

Modules accept a wide 14 - 35VDC power supply range (+24VDC nominal).

Their compact packages (2.13"x1.705"x0.605" max) save space and are ideal

for high channel density applications. They are designed for easy DIN rail

mounting using any of the -DIN backpanels.

SCM7B

▲

Features

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

Thermocouples

 Provides High Level Voltage Outputs

 1500Vrms Transformer Isolation

 Accuracy, ±0.03% of Span Typical,

±0.1% Max

 ANSI/IEEE C37.90.1 Transient Protection

 Input Protected to 120Vrms Continuous

 Noise, 500µV Peak (5MHz), 250µV RMS

(100kHz)

 CMRR, 160dB

 NMR, up to 85dB

 Easy DIN Rail Mounting

 CSA Certified, FM Approved

 CE and ATEX Compliant

Figure 1: SCM7B37 Block Diagram

For information call 800-444-7644

Refer to AN701 for V temperature conversion information

out

Isolated Process Control Signal Conditioning Products

SCM7B

Specifications

Module

Input

Signal Range Thermocouple

Typical at 25°C and +24VDC

SCM7B37

(1)

(See Ordering Information)

Bias Current -30nA

Resistance

Normal 50MΩ Power Off 30kΩ min Overload 30kΩ min

Protection

Continuous 120Vrms max

Transient ANSI/IEEE C37.90.1

Output

Signal Range

Effective Available Power

(2) 

(2)

40mW

Resistance <1Ω

Protection Continuous Short-to-Ground

Voltage/Current Limit ±12V, ±14mA

CMV (Input-to-Output)

Continuous 1500Vrms

Transient ANSI/IEEE C37.90.1

CMRR (50 or 60Hz) 160dB

(3)

Accuracy

Nonlinearity

(4)

±0.03% Span typical,

±0.1% Span max

See Ordering Information

Stability (-40°C to +85°C)

Gain ±35ppm/°C

Input Offset ±0.5µV/°C

Zero Suppression ±0.005%(Vz)

(5)

/°C

Output Offset ±0.002% Span/°C

Noise

Peak at 5MHz B/W 500µV

RMS at 10Hz to 100kHz B/W 250µV

Peak at 0.1Hz to 10Hz B/W 1µV RTI

CJC Accuracy

(6)

, ±0.25°C typ, ±1°C max

+5°C to +45°C ambient

Open Input Response Upscale

Open Input Detection Time <10s

Frequency and Time Response

Bandwidth, -3dB 3Hz

NMR (50/60Hz) 80/85dB

Step Response, 90% Span 165ms

Supply Voltage 14 to 35VDC

(2)

Current

Sensitivity ±0.0001%/%V

12mA

Mechanical Dimensions 2.13" x 1.705" x 0.605" max

(h)(w)(d) 54.1mm x 43.3mm x 15.4mm max

Environmental

Operating Temperature Range -40°C to +85°C

ATEX Group II, Category 3 -20°C to +40°C

Storage Temperature Range -40°C to +85°C

Relative Humidity 0 to 95% noncondensing

Emissions EN61000-6-4 ISM, Group 1

Radiated, Conducted Class A

Immunity EN61000-6-2 ISM, Group 1

R F Performance A ±0.5% Span Error

ESD, EFT, Surge, Voltage Dips Performance B

NOTES:

(1) Thermocouple characteristics per NIST monograph 175, ITS-90.

(2) Output Range and Supply Current specifications are based on minimum output load resistance.

Minimum output load resistance is calculated by V

Power that guarantees output range, accuracy, and linearity specifications.

(3) Accuracy includes the effects of repeatability, hysteresis, and linearity.

(4) Nonlinearity is calculated using the best-fit straight line method.

is the nominal input voltage that results in a 0V output.

(5) V

(6) The CJC sensor accuracy should be added to the module accuracy and thermocouple accuracy to

compute the overall measurement accuracy.

/PE, where PE is the output Effective Available

OUT

Ordering Information

(3)



Model

Input Range

Typical

SCM7B37J-01 100°C to +760°C ±0.03% ±0.1% ±0.01% ±0.02%

(-148°F to +1400°F) (0.26°C) (0.86°C) (0.09°C) (0.17°C)

SCM7B37J-10 0°C to +200°C ±0.03% ±0.1% ±0.01% ±0.02%

(+32°F to +392°F) (0.06°C) (0.20°C) (0.02°C) (0.04°C)

SCM7B37J-11 0°C to +400°C ±0.03% ±0.1% ±0.01% ±0.02%

(+32°F to +752°F) (0.12°C) (0.40°C) (0.04°C) (0.08°C)

SCM7B37J-12 0°C to +600°C ±0.03% ±0.1% ±0.01% ±0.02%

(+32°F to +1112°F) (0.18°C) (0.60°C) (0.06°C) (0.12°C)

SCM7B37J-13 300°C to +600°C ±0.03% ±0.1% ±0.01% ±0.02%

(572°F to +1112°F) (0.09°C) (0.30°C) (0.03°C) (0.24°C)

SCM7B37K-02 -100°C to +1350°C ±0.03% ±0.1% ±0.01% ±0.02%

(-148°F to +2462°F) (0.44°C) (1.45°C) (0.15°C) (0.29°C)

SCM7B37K-20 0°C to +300°C ±0.03% ±0.1% ±0.01% ±0.02%

(+32°F to +572°F) (0.09°C) (0.30°C) (0.03°C) (0.06°C)

SCM7B37K-21 0°C to +600°C ±0.03% ±0.1% ±0.01% ±0.02%

(+32°F to +1112°F) (0.18°C) (0.60°C) (0.06°C) (0.12°C)

SCM7B37K-22 0°C to +1200°C ±0.03% ±0.1% ±0.01% ±0.02%

(32°F to +2192°F) (0.36°C) (1.20°C) (0.12°C) (0.24°C)

SCM7B37K-23 600°C to +1200°C ±0.03% ±0.1% ±0.01% ±0.02%

Accuracy

(+1112°F to +2192°F) (0.18°C) (0.60°C) (0.06°C) (0.12°C)

SCM7B37T-03 -100°C to +400°C ±0.03% ±0.1% ±0.01% ±0.02%

(-148°F to +752°F) (0.15°C) (0.50°C) (0.05°C) (0.10°C)

SCM7B37E-04 0°C to +900°C ±0.03% ±0.1% ±0.01% ±0.02%

(+32°F to +1652°F) (0.27°C) (0.90°C) (0.09°C) (0.18°C)

SCM7B37R-05 0°C to +1750°C ±0.03% ±0.1% ±0.01% ±0.02%

(+32°F to +3182°F) (0.53°C) (1.75°C) (0.18°C) (0.35°C)

SCM7B37S-06 0°C to +1750°C ±0.03% ±0.1% ±0.01% ±0.02%

(+32°F to +3182°F) (0.53°C) (1.75°C) (0.18°C) (0.35°C)

SCM7B37B-07 0°C to +1800°C ±0.03% ±0.1% ±0.01% ±0.02%

(+32°F to +3272°F) (0.54°C) (1.80°C) (0.18°C) (0.36°C)







Output Ranges Available

Output Range Part No. Suffix Example

+1 to +5V NONE SCM7B37J-01

0 to +5V A SCM7B37J-01A

0 to +10V D SCM7B37J-01D



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

Nonlinearity

Typical Max Max

(4)

SCM7B

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