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Effective February 2013

Supersedes December 2006

Technical Data TD04703002E

Cam selection for

pushbutton selectors

Introduction

Selector switches in their varied forms

(two-position, three-position, four-position, and

Roto-Push) are a big factor contributing to the

great flexibility of control that a well-rounded line

of “pushbuttons” can achieve.

But because selector switches can be made

to perform in such complex and varied ways,

selection and application can be difficult. This is

only because a well thought-out approach is not

readily apparent.

This document provides a time-proven systematic

approach that will work in all cases.

Many complex selector switch control schemes

have been solved using the methods outlined

here. Even if you work with it only occasionally,

we ensure that you will be able to easily work

out the most complex schemes.

Cam and contact block selection is better

understood if you:

•

Work with each incoming and outgoing wire

(each circuit) separately

•

Recognize that the terms NO and NC only

identify the type of contact by its mode before

mounting it to the operator. The “X-O” chart

shows how that contact will act after assembly

to the operator with the selected cam shape

•

Each cam has two separate lobes, each of

which operates one of the two plungers on

the contact block independently of each other.

Those are identified as position A (top) and

position B (bottom). The position designations

give direction in selecting and mounting the

contact blocks

Contents

Description Page

Cam selection ............................2

Summary ................................3

Roto-Push. ...............................4

Contact block selection. ....................5

Three-position selector switch. ...............6

Four-position selector switch. ................7

Three-position Roto-Push switch. .............8

Glossary of terms. ........................10

Summary of content (12 pages)

PAGE 1
Technical Data TD04703002E Effective February 2013 Supersedes December 2006 Cam selection for pushbutton selectors Contents Description Introduction Page Cam selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Roto-Push.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Contact block selection. . . . . . . . . . . . . . . . . . . . . 5 Three-position selector switch.. . . . . . . . . . . . . . .
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Technical Data TD04703002E Cam selection for pushbutton selectors Effective February 2013 So, the secret of success is a careful, step-by-step analysis of the several elements that make up a complete operating scheme, taking one circuit at a time. Operating schemes that may seem complex at first can be broken down into a series of single circuits that are easy to analyze.
PAGE 3
Technical Data TD04703002E Cam selection for pushbutton selectors Effective February 2013 Contact block selection Summary Having selected the cam, contact block selection is simply a matter of gathering the A position and B position circuits into pairs that make up the most convenient contact block arrangement. If there is an imbalance in the number of circuits under A or B, then single circuit blocks must be selected for these leftover circuits.
PAGE 4
Technical Data TD04703002E Cam selection for pushbutton selectors Effective February 2013 An alternative grouping of the contacts for Cam 2 would avoid the need to consider the orientation. Roto-Push When using this grouping, however, care must be exercised when connecting the jumper from one block to the other. The previous grouping had the jumper connection between the contacts on the same block.
PAGE 5
Technical Data TD04703002E Cam selection for pushbutton selectors Effective February 2013 Contact block selection Maximum number of contact blocks that can be operated by each device is six except as noted in Table 5. Contact Block with Pressure Terminals Table 5.
PAGE 6
Technical Data TD04703002E Cam selection for pushbutton selectors Effective February 2013 Three-position selector switch Table 6.
PAGE 7
Technical Data TD04703002E Cam selection for pushbutton selectors Effective February 2013 Four-position selector switch Table 7.
PAGE 8
Technical Data TD04703002E Cam selection for pushbutton selectors Effective February 2013 Three-position Roto-Push switch A B NO NC Series Connection A B NO NC Parallel Connection NNote: The connections are not made at the factory. They are illustrated in the selection table as requirements, but must be made on the job. Roto-Push Operator Assembled with Contact Block Table 8.
PAGE 9
Technical Data TD04703002E Cam selection for pushbutton selectors Effective February 2013 Table 8.
PAGE 10
Technical Data TD04703002E Cam selection for pushbutton selectors Effective February 2013 Glossary of terms A NO, A NC, B NO, B NC Cam Convenient shorthand for NO and NC contacts positioned to be operated by cam lobe A or B. 1 2 Cam Slope 3 As the cam is rotated, the following occurs: A NO—B NC This is a shorthand method of writing “a normally open contact in the A position and wired in series with a normally closed contact in the B position,” etc.
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Cam selection for pushbutton selectors Technical Data TD04703002E Effective February 2013 eaton corporation www.eaton.
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Technical Data TD04703002E Effective February 2013 Cam selection for pushbutton selectors Eaton Corporation Electrical Sector 1111 Superior Avenue Cleveland, OH 44114 USA Eaton.com © 2013 Eaton Corporation All Rights Reserved Printed in USA Publication No. TD04703002E / Z13309 February 2013 Eaton is a registered trademark of Eaton Corporation. All other trademarks are property of their respective owners.