SCM5B33
Isolated True RMS Input Modules
FEATURES
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INTERFACES RMS VOLTAGE (0 鈥?300V) OR RMS CURRENT (0 鈥?5A)
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DESIGNED FOR STANDARD OPERATION WITH FREQUENCIES OF
45HZ TO 1000HZ (EXTENDED RANGE TO 20Khz)
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COMPATIBLE WITH STANDARD CURRENT AND POTENTIAL
TRANSFORMERS
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INDUSTRY STANDARD OUTPUTS OF EITHER 0-1MA, 0-20mA,
4-20MA, 0-5V OR 0-10VDC
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鹵0.25%
FACTORY CALIBRATED ACCURACY (ACCURACY CLASS
0.2)
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1500 VRMS CONTINUOUS TRANSFORMER BASED ISOLATION
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INPUT OVERLOAD PROTECTED TO 480V MAX (PEAK AC & DC) OR
10A RMS CONTINUOUS
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ANSI/IEEE C37.90.1-1989 TRANSIENT PROTECTION
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REGULATORY COMPLIANCE (TO BE DETERMINED)
DESCRIPTION
Each SCM5B33 True RMS input module provides a single channel of AC
input which is converted to its True RMS dc value, filtered, isolated,
amplified, and converted to a standard process voltage or current output
(Figure 1).
The SCM5B modules are designed with a completely isolated computer side
circuit which can be floated to
鹵50V
from Power Common, pin 16. This
complete isolation means that no connection is required between I/O
Common and Power Common for proper operation of the output switch. If
desired, the output switch can be turned on continuously by simply connecting
pin 22, the Read-Enable pin to I/O Common, pin 19.
The field voltage or current input signal is processed through a pre-amplifier
and RMS converter on the field side of the isolation barrier. The converted dc
signal is then chopped by a proprietary chopper circuit and transferred across
the transformer isolation barrier, suppressing transmission of common
mode spikes and surges. The computer side circuitry reconstructs, filters and
converts the signal to industry standard outputs. Modules are powered from
+5VDC,
鹵5%.
For current output models an external loop supply is required having a
compliance voltage of 14 to 48VDC. Connection, with series load, is between
Pin 20 (+) and Pin 19 (-).
4
+EXC
**
AC Source +In
I
IN
鈥揑n
**
鈥揈XC
4
6
3
5
2
1
3
Surge
Suppression
and
Protection
Pre-Amp,
Conversion
Isochopper鈩?/div>
Amplifier
Pat Pending
LPF
20
V
OUT or
I
OUT
*
+V
鈥揤
19
I/O Common
Isolated
Computer-Side
Power
22
RD EN\
Backpanel
Term Block
+V
* Current Input Models Only
** Add Jumpers for Current Input Modules
(provided with SCM5B33-06, 07)
鈥揤
17
Isolated
Field-Side
Power
Power
Oscillator
+5V
16
Power Common
FIGURE 1. SCM5B33 Block Diagram.
DATAFORTH
A Burr-Brown Company
廬
Call 800-444-7644
For Information and Assistance
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