7B14 NON-ISOLATED, LINEARIZED RTD INPUT

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Functional Description

7B14-C-02-1 The 7B14 is a low cost, single-channel signal conditioning module that interfaces, amplifies and filters input voltages from a wide variety of two- and three-wire platinum, copper and nickel Resistor Temperature Detectors (RTDs) and provides a precision output of either +1 V to +5 V or 0 V to +10 V, linear with temperature. Model 7B14 features a nonlinearity of ±0.05% maximum (Pt and Cu RTDs). RTD excitation current, three-wire lead resistance compensation and a predictable upscale open circuit indication provide a complete signal conditioning solution. Rated to operate with a nominal +24 V DC supply, Model 7B14 is mix-and-match and hot-swappable with other 7B Series input modules, so it can be inserted or removed from any socket in the same backplane without disturbing system power.

Inside the 7B14 Series Module

The three input pins of Model 7B14 are fully protected up to ±30 V DC. A 250 µA excitation current for platinum and nickel RTDs and a 1 mA excitation current for copper RTDs is provided to create an input voltage to the 7B14. This current also provides the upscale open circuit indication. A one-pole 3 Hz filter preconditions the RTD signal prior to amplification, provided by a low drift input amplifier. The output section contains a two-pole low pass filter (-3 dB @ 3Hz) and a buffer amplifier. The two-pole output filter and subsequent buffer ensure that a low noise, low impedance (<1 Ω) signal is available at the output to drive loads to 2 kΩ minimum.


7B14 FBD

Figure 1. 7B14 Functional Block Diagram

 

Input Types

100 Ω Platinum RTDs

120 Ω Nickel RTDs

10 Ω Copper RTDs

Output Options

+1 V to +5 V

0 V to +10 V

   7B14FCD

Figure 2. 7B14 Input Field Connections

7B14 Models Available

  Model RTD Sensor
(2- or 3-wire)		 Input Range Output Range Nonlinearity
(maximum)		 Accuracy
(maximum)
Order Now 7B14-01-1 100 Ω Pt, α = 0.00385 -100°C to +100°C +1 V to +5 V ±0.05% span ±0.15% span
Order Now 7B14-01-2 100 Ω Pt, α = 0.00385 -100°C to +100°C 0 V to +10 V ±0.05% span ±0.15% span
Order Now 7B14-02-1 100 Ω Pt, α = 0.00385 0°C to +100°C +1 V to +5 V ±0.05% span ±0.2% span
Order Now 7B14-02-2 100 Ω Pt, α = 0.00385 0°C to +100°C 0 V to +10 V ±0.05% span ±0.2% span
Order Now 7B14-03-1 100 Ω Pt, α = 0.00385 0°C to +200°C +1 V to +5 V ±0.05% span ±0.15% span
Order Now 7B14-03-2 100 Ω Pt, α = 0.00385 0°C to +200°C 0 V to +10 V ±0.05% span ±0.15% span
Order Now 7B14-04-1 100 Ω Pt, α = 0.00385 0°C to +600°C +1 V to +5 V ±0.05% span ±0.1% span
Order Now 7B14-04-2 100 Ω Pt, α = 0.00385 0°C to +600°C 0 V to +10 V ±0.05% span ±0.1% span
Order Now 7B14-05-1 100 Ω Pt, α = 0.00385 -50°C to +350°C +1 V to +5 V ±0.05% span ±0.1% span
Order Now 7B14-05-2 100 Ω Pt, α = 0.00385 -50°C to +350°C 0 V to +10 V ±0.05% span ±0.1% span

 

  Model RTD Sensor
(2- or 3-wire)		 Input Range Output Range Nonlinearity
(maximum)		 Accuracy
(maximum)
Order Now 7B14-C-02-1 10 Ω Cu, α = 0.004274 0°C to +120°C
(10 Ω @ +25°C)		 +1 V to +5 V ±0.05% span ±1.0% span
Order Now 7B14-C-02-2 10 Ω Cu, α = 0.004274 0°C to +120°C
(10 Ω @ +25°C)		 0 V to +10 V ±0.05% span ±1.0% span

 

  Model RTD Sensor
(2- or 3-wire)		 Input Range Output Range Nonlinearity
(maximum)		 Accuracy
(maximum)
Order Now 7B14-N-01-1 120 Ω Ni, α = 0.00672 0°C to +300°C +1 V to +5 V ±0.12% span ±0.3% span
Order Now 7B14-N-01-2 120 Ω Ni, α = 0.00672 0°C to +300°C 0 V to +10 V ±0.12% span ±0.3% span
Order Now 7B14-N-02-1 120 Ω Ni, α = 0.00672 0°C to +200°C +1 V to +5 V ±0.14% span ±0.3% span
Order Now 7B14-N-02-2 120 Ω Ni, α = 0.00672 0°C to +200°C 0 V to +10 V ±0.14% span ±0.3% span

7B14 Specifications
(typical @ +23°C ±5°C and Vs = +24 V dc)

Description Model 7B14
Input Ranges
RTD Types 100 Ω Platinum, 2-, 3-wire, α =0.00385
120 Ω Nickel, 2-, 3-wire, α =0.00672
10 Ω Copper, α =0.004274
Temperature Ranges Refer to Model Table
Custom Ranges Not Available*
Output Range Options (RL > 2 kΩ) +1 V to +5 V or 0 V to +10 V
Accuracy1
Initial @ +25°C Refer to Model Table
Nonlinearity2 Refer to Model Table
Input Offset vs. Temperature ±1 µV/°C
Zero Suppression vs. Temperature ±0.002% (Rz/Rspan)3/°C
Span vs. Temperature ±60 ppm/°C
Output Offset vs. Temperature ±0.002% Span/°C
Lead Resistance Effect ±0.02°C/Ω
Output Noise
5 MHz Bandwidth 1 mV peak
10 Hz to 100 Hz Bandwidth 0.4 mV rms
0.1 Hz to 10 Hz Bandwidth 0.6 µV peak
Bandwidth, -3 dB 3 Hz
Output Rise Time 250 ms
Normal Mode Rejection @ 50/60 Hz 60 dB
Input Protection ±30 V dc, continuous
Input Transient Protection ANSI/IEEE C376.90.1-1989
IEEE-STD 472
IEC 255-4, Class II
Output Resistance < 1 Ω
Voltage Output Protection Continuous Short to Ground
Power Supply
Voltage Range, Operating +14 V dc to +35 V dc
Current +25 mA, maximum
Sensitivity ±0.0001%/% of Vs
Mechanical Dimensions 1.663" x 2.11" x 0.563"
(42.24 mm x 53.6 mm x 14.3 mm)
Environmental
Temperature Range
   Operating -40°C to +85°C
   Storage -40°C to +85°C
Relative Humidity, 24 hours 0 to 90% @ +60°C noncondensing
ESD Sensitivity IEC 801-2, Level 2
RFI Susceptibility ±0.5% Span error @ 400 MHz, 5 Watt, 3 ft

Warm-up time required to meet specifications is approximately 10 minutes.
* Contact factory for OEM requirements.
1 Includes the combined effects of repeatability, hysteresis, and nonlinearity.
2 Nonlinearity is calculated using best-fit straight line method.
3 Rz is the value of the RTD resistance at the lowest measurement point. Rspan is the change in resistance over the measurement span.
Specifications subject to change without notice.

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