sensors(3).pdf

Table of Contents

Introduction ............................................................................. 2

Sensors ................................................................................... 4

Limit Switches ......................................................................... 8

International Limit Switches .................................................. 18

North American Limit Switches ............................................. 22

BERO Sensors ....................................................................... 27

Inductive Proximity Sensors Theory of Operation .................. 28

Inductive Proximity Sensor Family ......................................... 40

Capacitive Proximity Sensors Theory of Operation ................ 54

Capacitive Proximity Sensor Family ....................................... 57

Ultrasonic Proximity Sensors Theory of Operation ................. 59

Ultrasonic Proximity Sensor Family ....................................... 68

Photoelectric Sensors Theory of Operation ............................ 80

Photoelectric Family of Sensors ............................................ 93

Sensor Applications ............................................................... 99

Review Answers .................................................................. 107

Final Exam ........................................................................... 108

Introduction

Welcome to another course in the STEP 2000 series, S iemens

T echnical E ducation P rogram, designed to prepare our

distributors to sell Siemens Energy & Automation products

more effectively. This course covers Sensors and related

products.

Upon completion of Sensors you should be able to:

•

Describe advantages, disadvantages, and applications of

limit switches, photoelectric sensors, inductive sensors,

capacitive sensors, and ultrasonic sensors

•

Describe design and operating principles of mechanical

limit switches

•

Identify components of International and North American

mechanical limit switches

•

Describe design and operating principles of inductive,

capacitive, ultrasonic, and photoelectric sensors and

describe differences and similarities

•

Apply correction factors where appropriate to proximity

sensors

•

Identify the various scan techniques of photoelectric

sensors

•

Identify ten categories of inductive sensors and sensors in

each category

•

Describe the effects of dielectric constant on capacitive

proximity sensors

•

Identify environmental influences on ultrasonic sensors

•

Identify types of ultrasonic sensors that require manual

adjustment, can be used with SONPROG, and require the

use of a signal evaluator

•

Describe the difference between light operate and dark

operate modes of a photoelectric sensor

•

Describe the use of fiber optics and laser technology used

in Siemens photoelectric sensors

•

Select the type of sensor best suited for a particular

application based on material, sensing distance, and

sensor load requirements

This knowledge will help you better understand customer

applications. In addition, you will be better able to describe

products to customers and determine important differences

between products. You should complete Basics of Electricity

and Basics of Control Components before attempting

Sensors . An understanding of many of the concepts covered in

Basics of Electricity and Basics of Control Components is

required for Sensors .

If you are an employee of a Siemens Energy & Automation

authorized distributor, fill out the final exam tear-out card and

mail in the card. We will mail you a certificate of completion if

you score a passing grade. Good luck with your efforts.

BERO, SIMATIC, SONPROG, and SIGUARD are registered

trademarks of Siemens Energy & Automation, Inc.

National Electrical Code® and NEC® are registered trademarks

of the National Fire Protection Association, Quincy, MA 02269.

Portions of the National Electrical Code are reprinted with

permission from NFPA 70-1999, National Electrical Code

MA 02269. This reprinted material is not the complete and

official position of the National Fire Protection Association on

the referenced subject which is represented by the standard in

its entirety.

Underwriters Laboratories, Inc. is a registered trademark of

Underwriters Laboratories, Inc., Northbrook, IL 60062. The

abbreviation “UL” is understood to mean Underwriters

Laboratories, Inc.

National Electrical Manufacturers Association is located at 2101

L. Street, N.W., Washington, D.C. 20037. The abbreviation

“NEMA” is understood to mean National Electrical

Manufacturers Association.

Other trademarks are the property of their respective owners.

Sensors

One type of feedback frequently needed by industrial-control

systems is the position of one or more components of the

operation being controlled. Sensors are devices used to provide

information on the presence or absence of an object.

Siemens Sensors

Siemens sensors include limit switches, photoelectric ,

inductive, capacitive, and ultrasonic sensors. These products

are packaged in various configurations to meet virtually any

requirement found in commercial and industrial applications.

Each type of sensor will be discussed in detail. At the end of

the course an application guide is provided to help determine

the right sensor for a given application.

Technologies

Limit switches use a mechanical actuator input, requiring the

sensor to change its output when an object is physically

touching the switch. Sensors, such as photoelectric, inductive,

capacitive, and ultrasonic, change their output when an object is

present, but not touching the sensor.

In addition to the advantages and disadvantages of each of

these sensor types, different sensor technologies are better

suited for certain applications. The following table lists the

sensor technologies that will be discussed in this course.

Sensor

Advantages

Disadvantages

Applications

Limit Switch •High Current

Capability

•Low Cost

•Familiar "Low-

Tech" Sensing

•Requires Physical

Contact with

Target

•Very Slow

Response

•Contact Bounce

•Interlocking

•Basic End-of-

Travel Sensing

Photoelectric •Senses all Kinds of

Materials

•Long Life

•Longest Sensing

Range

•Very Fast

Response Time

•Lens Subject to

Contamination

•Sensing Range

Affected by Color

and Reflectivity

of Target

•Packaging

•Material

Handling

•Parts Detection

Inductive

•Resistant to Harsh

Environments

•Very Predictable

•Long Life

•Easy to Install

•Distance

Limitations

•Industrial and

Machines

•Machine Tool

•Senses Metal-

Only Targets

Capacitive

•Detects Through

Some Containers

•Can Detect

Non-Metallic

Targets

•Very Sensitive to

Extreme

Environmental

Changes

•Level Sensing

Ultrasonic

•Senses all

Materials

•Resolution

•Repeatability

•Sensitive to

Temperature

Changes

•Anti-Collision

•Doors

•Web Brake

•Level Control

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