Rockwell Automation 7000A PowerFlex Medium Voltage AC Drive - Air-Cooled (A Frame) - Manual (Page 326)

5-84
Component Definition and Maintenance
7000A-RM001A-EN-P – January 2011 7000 “A” Frame
Current Loop Transmitter
The current loop transmitter will transmit 4-20mA output to an external
receiver. The loop compliance on the transmitter is 12.5V. Loop
compliance is the maximum voltage at which a transmitter can generate to
achieve the maximum current and is usually a function of the power
supply voltage. Therefore, the PowerFlex 7000 transmitter can drive a
receiver with an input resistance up to 625 ohms. The figure below shows
a block diagram of the transmitter.
5V
DSP
FPGA
#
∩
Isolated
DC/DC
Converter
+15V
+15V
D/A
Current
Boost
Optical
Interface
20
18
19
21
IFM
Figure 5.63 – Process Loop Transmitter Block Diagram
This type of transmitter is known as a 4-wire transmitter, and will “sink”
current from a receiver. The receiver is connected by two wires only from
pins 20 (+ connection) and either pins 18, 19, 21 (- connection).
The recommended connection is shown above. The type of shielded cable
used is application specific and is determined by the length of the run, the
characteristic impedance and the frequency content of the signal.
ACB Analog Control
Board (cont.)