3B30/3B31 Isolated Voltage Input

The 3B30 and 3B31 are narrow-bandwidth (3Hz) single-channel signal conditioning modules which amplify, isolate, filter and protect analog input voltages and provide simultaneous precision voltage and current outputs. Each module performs complete signal conditioning, including isolating (±1500 V 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 overvoltage faults up to 220 V rms. The current output withstands 130 V 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 versions, Models 3B30-00 and 3B31-00, enable 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.

Inside the 3B30 and 3B31 Series Module

A chopper-stabilized low-drift (±1µV/°C) input amplifier assures stable 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 (Models 3B30-CUSTOM and 3B31-CUSTOM) or can be externally programmed (Models 3B30-00 and 3B31-00) via user supplied resistors inserted in the optional AC1310 plug-on ranging card. Internal lowpass filtering with a 4 Hz cutoff (-3 dB) 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 to provide a low-noise, low-impedance output voltage; this output also drives a voltage-to-current (V/I) converter to provide a simultaneous current output for interfacing versatility.

Figure 1. 3B30/3B31 Functional Block Diagram
Figure 2. 3B30 Input Field Connections	Figure 3. 3B31 Input Field Connections

Input Type	Dual Outputs
3B30: ±10 mV to ±100 mV	-10 V to +10 V
3B31: ±1 V to ±10 V	0 to 20 mA or 4 to 20 mA

	Model	Input Range	Output Ranges1
Order Now	3B30-00	Externally Programmable2	-10 V to +10 V & 0 mA to 20 mA
Order Now	3B30-01	-10 mV to +10 mV	-10 V to +10 V & 0 mA to 20 mA
Order Now	3B30-02	-50 mV to +50 mV	-10 V to +10 V & 0 mA to 20 mA
Order Now	3B30-03	-100 mV to +100 mV	-10 V to +10 V & 0 mA to 20 mA
	3B30-Custom	*	*
Order Now	3B31-00	Externally Programmable2	-10 V to +10 V & 0 mA to 20 mA
Order Now	3B31-01	-1 V to +1 V	-10 V to +10 V & 0 mA to 20 mA
Order Now	3B31-02	-5 V to +5 V	-10 V to +10 V & 0 mA to 20 mA
Order Now	3B31--03	-10 V to +10 V	-10 V to +10 V & 0 mA to 20 mA
	3B31-Custom	*	*

¹ Output current range may be user programmed to 4 mA to 20 mA using jumper supplied.
² Requires AC1310 ranging card.
* Custom Input/Output ranges are available. Refer to the Configuration Guide.

(typical @ +25°C and ±15 V dc, and +24 V dc Power)

Description	Model 3B30	Model 3B31
Input Range
Standard Ranges	±10 mV to ±100 mV	±1 V to ±10 V
Custom Ranges	±5 mV to ±500 mV	±0.5 V to ±20 V
Output Range
Voltage (RL > 2 KΩ)	-10 V to +10 V	*
Current (RL = 0 to 850Ω)1	4 mA to 20 mA or 0 mA to 20 mA	*
Maximum Current Output Span	0 mA to 31 mA	*
Accuracy2
Initial @ +25°C	±0.1% Span	*
Nonlinearity2	±0.01% Span	*
Stability vs. Temperature
Voltage Output
Zero	±1 µV/°C (RTI)	±25 ppm of Span/°C
Span	±25 ppm of Reading/°C	*
Current Output3
Zero	±25 ppm of Span/°C	*
Span	±25 ppm of Reading/°C	*
Zero and Span Adjustment Range4	±5% of Span	*
Input Bias Current	+3 nA	*
Input Resistance	15 MΩ	650 kΩ
Noise
Input, 0.1 Hz to 10 Hz Bandwidth	0.2 µV rms	*
Output, 100 kHz Bandwidth	50 µV rms	*
Bandwidth, -3 dB	3 Hz	*
Output Rise Time, 10% to 90% Span	200 ms	*
Common Mode Voltage (CMV)
Input-to-Output, Continuous	±1500 V peak, maximum	*
Transient	ANSI/IEEE C37.90.1-1989	*
Common Mode Rejection (CMR)
1 kΩ Source Imbalance, 50/60 Hz	160 dB	160 dB 150 dB (3B31-02); 145 dB (3B31-03)
Normal Mode Rejection, 50/60 Hz	60 dB	*
Input Protection, Signal and Excitation Voltage
Continuous	220 V rms maximum	*
Transient	ANSI/IEEE C37.90.1-1989	*
Voltage Output Protection	Continuous Short to Ground	*
Current Output Protection	130 V rms, continuous	*
Power Supply Voltages5
±15 V dc Supplies
Rated Operation	±(11.5 V dc to 16.5 V dc)	*
Current	±10 mA	*
Sensitivity	±0.01% span/V	*
+24 V dc Loop Supply
Rated Operation	+12 V dc to +30 V dc	*
Current	+27 mA @ lout = 20 mA	*
Sensitivity	±0.0002% span/V	*
Mechanical Dimensions	3.15" x 3.395" x 0.775" 80.0 mm x 86.2 mm x 19.7 mm)	*
Environmental
Temperature Range
Rated Performance	-25°C to +85°C	*
Storage	-55°C to +85°C	*
Relative Humidity, 24 hours	0 to 95% @ +60°C noncondensing	*
RFI Susceptibility	±0.5% Span error @ 400 MHz, 5 Watt, 3 ft	*

* Specifications same as model 3B30.
¹ For a 0 to 20 mA range, a typical minimum output current is 10 µA.
² Includes the combined effects of repeatability, hysteresis, and nonlinearity.
³ With respect to the voltage output.
⁴ A wide range of custom zero suppression and span is available with the 3B30-00 and 3B31-00 models, using the AC1310 ranging card.
⁵ +24 V dc loop power is required for driving the current output at loads up to 850Ω. If a current output load of 400Ω or less is applied, +15 V dc is sufficient for loop power. If only voltage output is used, loop power is not required.