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Ground loops, Power connections, Power connections 23 – Watlow CPC400 User Manual

Page 37

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CPC400 Series User’s Guide

Chapter 2: Installation

Doc. 0600-2900-2000

Watlow Anafaze

23

Ground Loops

Ground loops occur when current passes from the process
through the controller to ground. This can cause instru-
ment errors or malfunctions.

The best way to avoid ground loops is to minimize unneces-
sary connections to ground. Do not connect any of the fol-
lowing terminals to each other or to earth ground:

Power supply dc common

TB1 terminals 5, 6, 11, 12 (analog common)

TB1 terminal 17 (reference voltage common)

TB1 terminals 23, 24 (communications common)

TB2 terminal 2 (dc power common)

Power Connections

This section explains how to make power connections to the
CPC400 and the TB50.

Figure 2.11 CPC400 Series Controller with

TB18

Figure 2.12 CPC400 Series Controller with

TB50

TB2
(to power
supply)

TB1
(to signal
inputs

TB18
(to digital
outputs)

SCSI-2
(to TB50)

TB2
(to power
supply)

TB1
(to signal
inputs