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Analog inputs and outputs, Current loop transmitter – Rockwell Automation 7000L PowerFlex Medium Voltage AC Drive (C Frame) - Classic Control User Manual

Page 437

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Component Definition and Maintenance 6-93

7000 “C” Frame

7000L-UM300I-EN-P – June 2013

Analog Inputs and Outputs


The PowerFlex 7000L “C” Frame drive offers one isolated process
current loop transmitter and one isolated process current loop
receiver, embedded into the control. These are accessible on the
CIB.


Each of these can be configured independently as either 0-20mA or
4-20mA. (Refer to Programming Manual).


The following information will show the connections for each.

Current Loop Transmitter

The current loop transmitter will transmit either 0-20mA or 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 7000L transmitter can drive a receiver with an input
resistance up to 625 ohms. The figure below shows a block diagram
of the transmitter.

DSP

FPGA

Optical

Interface

D/A

Current

Boost

Isolated

DC/DC

Converter

+15V

+5V

1

2

3

4

J4A

+15V

DSP

FPGA

Optical

Interface

D/A

Current

Boost

Isolated

DC/DC

Converter

+15V

+5V

1

2

3

4

J4A

+15V


Figure 6.70 – 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 1 (+ connection) and either pins 2, 3 or 4 (- connection).


The recommended connection is shown below. 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.