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Functional Description
 The 7B33 is a single-channel
signal conditioning module that interfaces, amplifies and
filters unipolar voltage inputs and provides a protected
precision output of either +1 V to +5 V or 0 V to +10 V.
To measure a process current input, a plug-on 250  current
sensing resistor, Model AC1391, may be installed directly
on the 7B backplane, using available pin sockets. The external
current sense resistor allows the current loop to be maintained
even when the module is removed from the backplane. Model
7B33 features a nonlinearity of ±0.02% maximum and an accuracy
of ±0.1% maximum (±0.01% typical). To accurately measure
low level signals in electrically noisy environments, 1500
V rms of galvanic transformer-based isolation with a common
mode rejection (CMR) of 105 dB @ 50/60 Hz is provided. Rated
to operate with a nominal +24 V DC supply, Model 7B33 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 7B33 Series Module
The two input pins of Model 7B33 are fully protected up
to 120 V rms line voltage. A one-pole 100 Hz filter preconditions
the input signal prior to amplification by a low drift input
amplifier. Amplitude modulation is used to implement transformer
isolation (1500 V rms input-to-output and power). Isolated
front-end circuitry power is supplied by a DC/DC converter.
The output section contains a two-pole low pass filter (-3
dB @100 Hz), a buffer amplifier and a power oscillator.
The two-pole output filter and subsequent buffer ensures
that a low noise, low impedance (<1 )
signal is available at the output to drive loads of 2 kminimum.
Figure 1. 7B33 Functional Block diagram
Inputs
- +1 V to +5 V
- 0 V to +5 V
- 0 to 20 mA
- 4 mA to 20 mA
Output Options
- +1 V to +5 V
- 0 V to +10 V
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Figure 2. 7B33 Input Field Connections
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7B33 Models Available
| Model |
Input Range |
Output Range |
|
7B33-01-1
|
+1 V to +5 V |
+1 V to +5 V |
|
7B33-01-2
|
0 V to +5 V |
0 V to +10 V |
|
7B33-01-1
|
+4 mA to +20 mA1 |
+1 V to +5 V |
|
7B33-01-2
|
0 mA to +20 mA1 |
0 V to +10 V |
| 1Models
7B33-01-1 and 7B33-01-2 may be used to measure a
process current input by installing a 250
current sensing resistor, such as Model AC1391,
on the backplane. With this resistor installed,
the current loop is maintained even when the module
is removed from the backplane. |
7B33 Specifications
(typical @ +23℃ ±5℃ and Vs
= +24 V dc)
| Description |
Model 7B33 |
Input Range1 |
| Standard Ranges |
+1 V to +5 V; 0 V to +5 V (Refer
to Model Table) |
| Custom Ranges |
Not Available* |
| Output Range Options (RL
> 2 k) |
+1 V to +5 V or 0 V to +10 V |
Accuracy1 |
| Initial @ +25℃ |
±0.01% Span (±0.1% Span, maximum) |
| Nonlinearity3 |
±0.02% Span, maximum |
| Input Offset vs. Temperature |
N/A4 |
| Span vs. Temperature |
±15 ppm/℃ |
| Output Offset vs. Temperature |
±0.003% span/℃ |
| Input Bias Current |
±0.1 nA |
Input Resistance |
| Power ON |
2 M |
| Power OFF |
30 k,
minimum |
Output Noise |
| 5 MHz Bandwidth |
6 mV peak |
| 10 Hz to 100 kHz Bandwidth |
0.4 mV rms |
| 0.1 Hz to 10 Hz Bandwidth |
4 µV peak |
| Bandwidth, -3 dB |
100 Hz |
| Output Rise Time, 10% to 90% Span |
10 ms |
| Common-Mode Voltage (CMV) |
| Input-to-Output and Power |
1500 V rms continuous |
Common Mode Rejection (CMR) |
| Input-to-Output and Power @ 50/60
Hz |
105 dB |
| Input Protection |
120 V rms, continuous
±35 V dc, continuous |
| Input Transient Protection |
ANSI/IEEE C376.90.1-1989
IEEE-STD 472
IEC 255-4, Class II |
| Output Resistance |
< 1 |
| Voltage Output Protection |
Continuous Short to Ground |
Power Supply |
| Voltage Range, Operating |
+14 V dc to +35 V dc |
| Current |
+20 mA, maximum |
| DSensitivity |
±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) |
| Weight |
60 grams |
| Environmental |
| Temperature Range |
| Operating |
-40℃ to +85℃ |
| Storage |
-40℃ to +85℃ |
| Relative Humidity, 24 hours |
0 to 90% @ +60℃ 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.
1Model 7B33 may be used to measure a
process current input by installing a 250 current
sensing resistor, such as Model AC1391, on the backplane.
With this resistor, the current loop is maintained
even when the 7B33 module is removed from the backplane.
2Includes the combined effects of repeatability,
hysteresis, and nonlinearity.
3Nonlinearity is calculated using best-fit
straight line method.
4 Input offset term is included in the
output offset specification
Specifications subject to change without notice.
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