3B32

Rev. 0 | Page 2 of 8

GENERAL DESCRIPTION

The 3B32 is a single-channel signal conditioning module that

interfaces, amplifies and filters a process-current input and

provides simultaneous precision output voltage and current.

Process-current input signals are measured by reading the

voltage across an external precision 100Ω resistor (supplied).

Model 3B32 performs complete signal conditioning, including

isolating (+1500V peak input-to-output and power) and

protecting their computer side outputs from damage and loss of

signal integrity, and shielding their inputs from damage from

field-side over-voltage faults up to 220V rms. The current

output withstands 130V rms without damage and interfaces

user equipment through screw terminals located on the 3B

Series backplane. Each plug-in, mix-and-match, hot-swappable

module is easily field calibrated via front-panel zero and span

adjustments for both voltage and current outputs.

3B Series Custom-Ranging Program – Externally-

programmable Model 3B32-00, enables the user to configure a

special input range by using the optional plug-on AC1310

ranging card, which houses user-supplied resistors to determine

zero and span. To facilitate selecting resistors, a Windows

program, 3B-CUSTOM, calculates resistor values based on the

user-desired input/output ranges.

assures long-term stability. At the amplifier input, a stable,

zero-scale input voltage is subtracted from the input signal to

set the zero-scale value. Zero suppression can exceed 100% of

the input range. This is ideal for expanded-scale applications

requiring high-resolution measurement of a selected portion of

an input signal. For user convenience, the zero and span can be

factory configured to meet custom range needs (Model 3B32-

CUSTOM) or can be externally programmed (Model 3B32-00)

via user supplied resistors inserted in the optional AC1310 plug-

on ranging card. Internal low-pass filtering with a 3Hz cutoff (-

3dB) two-pole Butterworth filter enhances both 60 dB normal-

mode and 160 dB common-mode rejection at 50/60 Hz,

enabling accurate measurement of small signals in high

electrical noise.

Signal isolation is accomplished by transformer coupling with a

proprietary modulation technique for linear, stable and reliable

performance. The differential input circuit on the field side is

fully floating, eliminating the need for any input grounding. A

demodulator on the computer side of the signal transformer

recovers the original signal, which is then filtered and buffered

and drives a voltage-to-current converter to provide the current

output.

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Figure 2