Functional Description

3B37-K-02 The 3B37 is a single-channel signal conditioning module that interfaces, amplifies and filters input voltages from a J, K, T, E, R, S or B-type thermocouple and provides isolated simultaneous voltage and current outputs linear with input voltage. High accuracy internal cold junction compensation and a predictable upscale open circuit indication provide a complete signal conditioning solution. To accurately measure low level signals in electrically noisy environments, ±1500 V peak of galvanic transformer-based isolation with a common mode rejection (CMR) of 160 dB @ 50/60 Hz and a normal mode rejection (NMR) of 60 dB @ 50/60 Hz are provided. The current output withstands 130 V rms without damage and interfaces user equipment through screw terminals located on the 3B Series backplane. This 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.

Accurate and System-Ready

Internal cold-junction compensation largely corrects errors arising from parasitic thermocouples formed by thermocouple connection to the input screw terminals, providing an accuracy of ±0.5°C over the +5°C to + 45°C ambient temperature range. The module generates a predictable upscale signal to indicate an open thermocouple; for a downscale response, connect a 47 MΩ, 0.25 Watt resistor across screw terminals 2 and 4 on the 3B Series backplane.

3B Series Custom-Ranging Program

Externally-programmable version Model 3B37-X--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 3B37 Module

A chopper-stabilized low-drift input amplifier assures stable long-term stability. At the amplifier input, a zero-scale input voltage is subtracted from the input signal to set the zero-scale value. For user convenience, the zero and span optionally can be factory configured to meet custom needs (Model 3B37-CUSTOM) or can be externally programmed (Model 3B37-X-00) via user-supplied resistors inserted in the optional AC1310 plug-on ranging card. Zero suppression can exceed 100% of the input range. This enables suppression of a zero-scale input value many times larger than the total span for precise expanded-scale measurements of a selection portion of an input signal. The differential input circuit on the field side is fully floating, eliminating the need for any input grounding. Signal isolation by transformer coupling uses a proprietary modulation technique for linear, stable and reliable performance 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. 3B37 Functional Block Diagram


Figure 2. 3B37 Input Field Connections


Input Type

J, K, T, E, R, S, B

Dual Outputs

0 to +10 V or -10 V to +10 V

0 to 20 mA or 4 to 20 mA

3B37 Models Available

  Model Input Type Input Range Output Ranges1
Order Now 3B37-X-00 Type J, K, T, E, R, S, or B Externally Programmable 2 0 V to +10 V & 0 mA to 20 mA
Order Now 3B37-J-01 Type J -100°C to +100°C (-148°F to +1400°F) 0 V to +10 V & 0 mA to 20 mA
Order Now 3B37-K-02 Type K -100°C to +1350°C (-148°F to +2462°F) 0 V to +10 V & 0 mA to 20 mA
Order Now 3B37-T-03 Type T -100°C to +400°C (-148°F to +752°F) 0 V to +10 V & 0 mA to 20 mA
Order Now 3B37-E-04 Type E 0°C to +900°C (+32°F to +1652°F) 0 V to +10 V & 0 mA to 20 mA
Order Now 3B37-R-05 Type R 0°C to +1750°C (+32°F to +3182°F) 0 V to +10 V & 0 mA to 20 mA
Order Now 3B37-S-05 Type S 0°C to +1750°C (+32°F to +3182°F) 0 V to +10 V & 0 mA to 20 mA
Order Now 3B37-B-06 Type B 0°C to +1800°C (+32°F to +3272°F) 0 V to +10 V & 0 mA to 20 mA
  3B37-Custom Type J, K, T, E, R, S, or B * *

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 configuration guide.

3B37 Specifications
(typical @ +25°C and ±15 V dc, and +24 V dc Power)

Description Model 3B37
Input Ranges
Standard Ranges Refer to Model Table
Custom Ranges ±5 mV to ±500 mV
Output Ranges
Voltage (RL > 2 K ) 0 V to +10 V; -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
Initial @ +25°C ±0.1% Span + CJC Sensor Error
Nonlinearity ±0.01% Span
Stability vs. Temperature
Voltage Output
   Zero ±0.02°C/°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
Cold Junction Compensation (CJC)5
Initial Accuracy @ +25°C ±0.5 °C
Accuracy vs. Temperature, +5°C to +45°C ±0.5°C (±0.0125°C/°C)
Input Bias Current +15 nA
Input Resistance 15 MΩ
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
Open Input Response Upscale
Open Input Detection Time 10 seconds
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
Normal Mode Rejection, 50/60 Hz 60 dB
Input Protection
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 Voltages 6
±15 V dc Supplies
   Rated Operation ±(11.5 V dc to 16.5 V dc)
   Current ±12 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)
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

1 For a 0 mA 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 When used with the CJC temperature sensor provided on the 3B Series backplane.
6 +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.
Specifications subject to change without notice.

Send Feedback X
content here.
content here.

Send Feedback