Impulse SCM7B35 User Manual

Isolated Process Control Signal Conditioning Products

SCM7B35

Isolated 2-Wire Transmitter Interface Modules With Loop Power

Description

SCM7B35 current input modules accept input signals in the 4-20mA range from

the field and provide a high level voltage output to the process control system

(Figure 1). Current to voltage conversion occurs internal to the module, which

is factory calibrated to ensure the highest accuracy.

Loop power is provided by the module, enabling a 2-wire transmitter to be

directly connected without the need for a separate dc power supply for the 2-

wire transmitter.

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 18 - 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.

▲

Features

 2-Wire Transmitter Interface

 Accepts 4-20mA Signals

 Provides an Isolated +24VDC Supply to

Power the Loop

 Provides High Level Voltage Outputs

 1500Vrms Transformer Isolation

 Accuracy, ±0.03% of Span Typical,

±0.1% Max

 ANSI/IEEE C37.90.1 Transient Protection

 120Vrms Input Protection

 CMRR, 105dB

 80dB Per Decade of Attenuation

Above 100Hz

 Easy DIN Rail Mounting

 CSA Certified, FM Approved

 CE and ATEX Compliant

SCM7B

Figure 1: SCM7B35 Block Diagram

For information call 800-444-7644

Isolated Process Control Signal Conditioning Products

SCM7B

Specifications

Module

Typical at 25°C and +24VDC

SCM7B35

Input

Signal Range 4-20mA

Protection

Continuous 120Vrms max

Transient ANSI/IEEE C37.90.1

Loop Voltage

Output

Signal Range

Effective Available Power

(1)

(2)

+24VDC

See Ordering Information

40mW

Resistance <1Ω

Protection Continuous Short-to-Ground

Voltage/Current Limit ±16V, ±14mA

CMV (Input-to-Output)

Continuous 1500Vrms

Transient ANSI/IEEE C37.90.1

CMRR (50 or 60Hz) 105dB

(3)

Accuracy

Nonlinearity

(4)

±0.03% Span typical,

±0.1% Span max

±0.01% Span typical,

±0.02% Span max

Stability (-40°C to +85°C)

Gain ±40ppm/°C

Input Offset N/A

(5)

Output Offset ±0.003% Span/°C

Noise

Peak at 5MHz B/W 5mV

RMS at 10Hz to 100kHz B/W 500µV

Peak at 0.1Hz to 10Hz B/W 3µV RTI

Frequency and Time Response

Bandwidth, -3dB 100Hz

NMR (-3dB at 100Hz) 80dB per decade above 100Hz

Step Response, 90% Span 5m s

Supply Voltage 18 to 30VDC

(2)

Current

Sensitivity ±0.0002%/%V

56mA

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) +24V will be supplied to the loop for an open loop condition. Approximately +22V to +16V will be

supplied for a corresponding 4mA to 20mA input. Loop voltage is independent of supply voltage.

(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.

(5) Input offset term included in output offset specification.

/PE, where PE is the Output Effective Available

OUT

Ordering Information

Model Input Range Output Range

SCM7B35-01 4 to 20mA +1 to +5V

SCM7B35-01A 4 to 20mA 0 to +5V

SCM7B35-01D 4 to 20mA 0 to +10V

SCM7B35-02 4 to 20mA +2 to +10V

SCM7B

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