Impulse SCM7B34, SCM7B34N User Manual

Isolated Process Control Signal Conditioning Products

SCM7B34/34N

Isolated Linearized 2- or 3-Wire RTD Input Modules

Description

Each SCM7B34/34N RTD input module accepts a single channel of 100Ω Platinum (α = 0.00385) or 120Ω Nickel (α = 0.00672) RTD input and produces

an input voltage in response to a low level current excitation. The input signal

is filtered, isolated, amplified, linearized, and converted to a high level analog

voltage for output to the process control system (Figure 1).

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.

In response to the low level current excitation signal, the RTD input signal is

chopped by a proprietary chopper circuit and transferred across the trans-

former isolation barrier, suppressing transmission of common mode spikes and

surges. The signal is then reconstructed and filtered for process control system

output.

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 specific RTD non-linearity. Lead

compensation is achieved by matching two current paths thus cancelling the

effects of lead resistance.

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 100Ω Platinum or 120Ω

Nickel RTDS

 Provides 250µA RTD Excitation Current

 Linearizes RTD Signal Response

 Provides High Level Voltage Outputs

 1500Vrms Transformer Isolation

 Accuracy, ±0.05% to ±0.15% of

Span Typical

 Nonconformity, ±0.025% to ±0.07% of

Span Typical

 ANSI/IEEE C37.90.1 Transient Protection

 Input Protected to 120Vrms Continuous

 Noise, 500µV Peak (5MHz), 250µV RMS

(100kHz)

 CMRR, up to 160dB

 NMR, up to 85dB

 Easy DIN Rail Mounting

 CSA Certified, FM Approved

 CE and ATEX Compliant

Figure 1: SCM7B34/34N Block Diagram

For information call 800-444-7644

Isolated Process Control Signal Conditioning Products

SCM7B

Specifications

Typical at 25°C and +24VDC

Module SCM7B34 SCM7B34N

Input

Signal Range 100Ω Pt RTD 120Ω Ni RTD

Protection

Continuous 120Vrms max *

Transient ANSI/IEEE C37.90.1 *

Sensor Excitation Current

(1)

Lead Resistance Effect ±0.02°C/Ω max *

Output

Signal Range

Effective Available Power

(2) 

(2)

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

Nonconformity

(4)

Stability (-40°C to +85°C)

Gain ±60ppm/°C *

Input Offset ±1µV/°C *

Zero Suppression ±0.002%(RZ/R

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 *

Open Input Response

+ Lead Upscale *

 Lead Non-deterministic *

x Lead Downscale *

Open Input Detection Time <5s *

Frequency and Time Response

Bandwidth, -3dB 3Hz *

NMR (50/60Hz) 80/85dB *

Step Response, 90% Span 250ms *

Supply Voltage 14 to 35VDC *

(2)

Current

Sensitivity ±0.0001%/%V

Mechanical Dimensions 2.13" x 1.705" x 0.605" max *

(h)(w)(d)

Environmental

Operating Temperature Range

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:

*Specification same as preceding model.

(1) Sensor excitation current is model dependent.

(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 conformity specifications.

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

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

is the value of the RTD resistance at the lowest measurement point. R

(5) R

resistance over the measurement span.

See Ordering Information *

≈250µA *

40mW *

See Ordering Information *

(5)

)

/°C *

SPAN

12mA *

54.1mm x 43.3mm x 15.4mm max

-40°C to +85°C *

/PE, where PE is the output Effective Available

OUT

is the change in

SPAN

Ordering Information

Model Input Range

100

SCM7B34-01 -100°C to +100°C ±0.075% ±0.15% ±0.025% ±0.05%

SCM7B34-02 0°C to +100°C ±0.10% ±0.2% ±0.025% ±0.05%

SCM7B34-03 0°C to +200°C ±0.075% ±0.15% ±0.025% ±0.05%

SCM7B34-04 0°C to +600°C ±0.05% ±0.1% ±0.025% ±0.05%

SCM7B34-05 -50°C to +350°C ±0.05% ±0.1% ±0.025% ±0.05%

120

SCM7B34N-01 0°C to +300°C ±0.15% ±0.3% ±0.06% ±0.12%

SCM7B34N-02 0°C to +200°C ±0.15% ±0.3% ±0.07% ±0.14%







Output Ranges Available

Output Range Part No. Suffix Example

+1 to +5V NONE SCM7B34-01

0 to +5V A SCM7B34-01A

0 to +10V D SCM7B34-01D

**RTD Standards

Type Alpha Coefficient DIN JIS

Ω Pt 0.00385 DIN 43760 JIS C 1604-1989

100

120Ω Ni 0.00672

ΩΩ

Ω Pt **

ΩΩ

Ω Ni **

ΩΩ

Accuracy

Typical

(2)

Nonconformity

Typical Max Max

(-148°F to +212°F) (0.15°C) (0.30°C) (0.05°C) (0.10°C)

(+32°F to +212°F) (0.10°C) (0.20°C) (0.025°C) (0.05°C)

(+32°F to +392°F) (0.15°C) (0.30°C) (0.05°C) (0.10°C)

(+32°F to +1112°F) (0.30°C) (0.60°C) (0.15°C) (0.30°C)

(-58°F to +662°F) (0.20°C) (0.40°C) (0.1°C) (0.20°C)

(+32°F to +572°F) (0.45°C) (0.90°C) (0.18°C) (0.36°C)

(+32°F to +392°F) (0.30°C) (0.60°C) (0.14°C) (0.28°C)

(3)

SCM7B

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