Impulse SCM7B35 - Manual

Isolated Process Control Signal Conditioning Products SCM7B
For information call 800-444-7644 74
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.
Figure 1: SCM7B35 Block Diagram
▲
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