Rockwell Automation T80004 Application Note Field Loop Configuration - Manual (Page 8)

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AN-T80004 Field Loop Configuration
Issue 10 Jun 13 AN-T80004 8
The current loop allows 4mA to drive the device electronics. However, most field devices need higher
power. This must be provided with a separate power connection. This is now a three wire device. Note
that the fuses on the FTA should not be replaced with higher rating fuses because a short between the
fuse and the channel input may damage the channel. VFTAs include a zero volt terminal, but if FTAs
are used, fit a separate zero volt terminal.
Some devices have another connection. These have separate zero volt power and current loop return
connections, allowing the current loop to be isolated. For 8000 series analogue inputs, wire the two
connections together.
24V
Channel
0V
System circuit Active field loop
24V
Channel
0V
System circuit Active field loop
PSU