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FEATURES
● INTERFACES RMS VOLTAGE (0 – 300V) OR RMS CURRENT (0 – 5A)
● DESIGNED FOR STANDARD OPERATION WITH FREQUENCIES OF
45HZ TO 1000HZ (EXTENDED RANGE TO 20Khz)
● COMPATIBLE WITH STANDARD CURRENT AND POTENTIAL
TRANSFORMERS
● INDUSTRY STANDARD 0-5V OUTPUT
● ±0.25% FACTORY CALIBRATED ACCURACY (ACCURACY CLASS
0.2)
● 1500 VRMS CONTINUOUS TRANSFORMER BASED ISOLATION
● INPUT OVERLOAD PROTECTED TO 480V MAX (PEAK AC & DC) OR
10A RMS CONTINUOUS
● ANSI/IEEE C37.90.1-1989 TRANSIENT PROTECTION
DESCRIPTION
Each OM5-IAC 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 OM5-IAC modules are designed with a completely isolated computer
side circuit which can be floated to ±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 a 0-5VDC output. Modules are powered from +5VDC,
±5%.
FIGURE 1. OM5-IAC Block Diagram.
+InAC Source
–In
–EXC
Backpanel
Term Block
6
5
3
Surge
Suppression
and
Protection
Pre-Amp,
Conversion
*
* Current Input Models Only
Isolated
Field-Side
Power
4
3
2
1
+EXC
–V
+V
I
IN
4
–V
LPF
+V
Power
Oscillator
Isolated
Computer-Side
Power
V
OUT
or
I
OUT
20
22
I/O Common
RD EN\
+5V
17
16
Power Common
19
Isochopper™
Amplifier
Pat Pending
OM5-IAC
Isolated True RMS Input Modules