Maintaining and repairing mechatronic devices and systems

Information Sheet 7.1.1: Sensor; Design, Selection, Specification and Implementation

Learning outcomes:
7 Inspect and test the repaired mechatronics devices and systems.
Learning Activity:
7.1 Familiarize some specific troubleshooting techniques.

Sensors; Design, Selection, Specification and Implementation

Proximity Sensor Product Marketing, Omron Electronics LLC
When your application calls for metallic target sensing that falls within an inch of the sensing surface, the
inductive proximity sensor fits nicely into your design criteria. These durable sensors are suitable for harsh
environments. They have dust and dirt materials build up immunity. Industrial inductive proximity sensors first
came out in the early 1960s and today have a proven track record in the sensing arena. They also generally have
standardized behaviors.

This information sheet discusses the rudimentary design of the inductive proximity sensor, and goes on to show a

selection method that accounts for conditional application and device requirements. The article then teaches key
inductive proximity sensor specifications followed by a discussion of mounting restrictions for the sensor’s

implementation. Together, this information will supply a designer with the knowledge required for a successful

inductive proximity sensor to object detection design.

Inductive Sensor Design

Inductive proximity sensors operate under the electrical principle of inductance. Inductance is the phenomenon

where a fluctuating current, which by definition has a magnetic component, induces an electromotive force (emf)
in a target object. In circuit design, one measures this inductance in H (henrys). To amplify a device’s inductance

effect, a sensor manufacturer twists wire into a tight coil and runs a current through it.

An inductive proximity sensor has four components; the coil, oscillator, detection circuit and output circuit. The
oscillator generates a fluctuating magnetic field the shape of a doughnut around the winding of the coil that
locates in the device’s sensing face.

When a metal object moves into the inductive proximity sensor’s field of detection, Eddy circuits build up in the
metallic object, magnetically push back, and finally dampen the Inductive sensor’s own oscillation field. The
sensor’s detection circuit monitors the oscillator’s strength and triggers an output from the output circuitry when
the oscillator becomes dampened to a sufficient level.

Designers should consider two types of inductive proximity sensors when selecting an inductive sensor; shielded
and unshielded. When current generates in the sensor’s coil the doughnut effect it causes the proximity sensor to

trigger when any object comes behind, alongside or in front of the device. Shielding uses a ferrite core to direct
the coil’s magnetic field to radiate only from the sensor’s detection face. Unshielded inductive proximity sensors

are not completely unshielded. A peeled back ferrite core shielding in the unshielded case allows for a longer

sensing distance, while still preventing sensing due to objects behind the detection face.

Understanding the operation, the magnetic nature, and the shielding of the inductive proximity sensor is helpful
when considering the influences of target material, environment, and mounting restrictions on the sensor itself
and in your design.

Inductive Sensor Selection

Inductive proximity sensors categorize in five specific types; cylindrical, rectangular, miniature, harsh
environment, and special purpose. 70% of all inductive proximity sensor purchases are of the standardized
cylindrical threaded barrel type. When one considers this statistic, it is easy to understand why a designer would
specify into their application a general-purpose (or standardized) inductive proximity sensor. 70% of the time, he
would be correct. Experience has shown, however, that applications in need of inductive sensing usually warrant
the examination of a few additional design criteria.

These conditional criteria eliminate (or specify) the more special inductive proximity sensors available first before
falling upon the general purpose inductive proximity sensor. The three guiding beliefs of inductive proximity
sensor selection are target material, environment, and mounting restrictions.

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Information Sheet 7.1.1: Sensor; Design, Selection, Specification and Implementation

Target Materials
In the world of inductive proximity sensors, not all metals are created equally. A designer can find himself looking
for a quick fix to an inductive sensing problem that would vanish if a special inductive sensor was selected. The
inductive proximity sensor specification that we have all become familiar with in technical data sheets worldwide
references a “standard detectable object” made of an iron (ferrous) material. Other metallic materials, such as
stainless steel, brass, aluminum, and copper have different influence over the inductive effect and are usually less
detectable than iron.

Is the target material an iron object? Will the target material change in future runs of the application?

Examine the sensing distance reductions for typical inductive proximity sensors below.

Stainless Steel = Standard Sensing Distance X .8
Brass = Standard Sensing Distance X .5
Aluminum = Standard Sensing Distance X .4
Copper = Standard Sensing Distance X .3

A designer’s full line sensor supplier will have a solution for his inductive proximity sensor’s detection of
troublesome metallic materials. Manufacturer’s terms for these special inductive proximity sensors are “non-
ferrous sensing” or “all metal sensing.” “Non-ferrous sensing”

Inductive proximity sensors will detect non-ferrous metals such as aluminum better than they sense iron. “All
metal sensing” inductive proximity sensors will detect all metallic materials at the same sensing distance.

What separates the “non-ferrous sensing” and “all metal sensing” inductive proximity sensor from the standard (or
general-purpose) inductive proximity sensor is the number of separate inductive coils included in the proximity
sensor head. The “non-ferrous sensing” or “all metal sensing” inductive proximity sensor will include two or three
separate coils in the proximity sensor head while the general-purpose inductive proximity sensor will include only
one coil. The main trades between a “non-ferrous sensing” or an “all metal sensing” type proximity sensor and a
general-purpose proximity sensor are the cost and body size. “Non-ferrous sensing” and “all metal sensing”
proximity sensors tend to be more expensive due to the increased number of coils required and have larger
enclosures than their traditional inductive proximity sensor counterparts.

Environment
Environmental conditions can have far and sweeping effects upon the inductive proximity sensor.
These effects specifically refer to sensor life, but can only be related to premature failure (false trigger or
otherwise) of the inductive proximity sensor once installed into its component mounting position.

Nevertheless, your full line sensor supplier has many solutions to specific environmental conditions.

Is the application one in which metallic chips or filings are prone to build up on the side or face of the

inductive proximity sensor?

Intelligent semi-conductor microprocessors found in some modern inductive proximity sensors have the ability to
detect the slow build up of metal filings or “chips” over time and teach the inductive proximity sensor to ignore
their effects. Sensor suppliers call this specialized inductive proximity sensor a “chip immune” type.

Another type of inductive proximity sensor that is resilient against chip build up is the flat-pack proximity sensor.
The slim profile of the flat pack proximity sensor when mounted with its sensing face exposed vertically is virtually
unaffected by chip build up on its slim horizontal component.

Is the inductive proximity sensor exposed to cutting fluids or chemicals for prolonged periods of time?
In the face of cutting fluids or corrosive chemicals, a traditional inductive proximity sensor may become brittle and
crack, shortening its life.

In such cases, a designer must again turn to a specialized inductive proximity sensor. Proximity sensors dipped,
coated or shot from fluoroplastic suffer no ill effects from the material in terms of performance or reliability.
Fluoroplastic's stability against cutting oils and corrosive chemicals outweigh the additional costs that come with a
product manufactured with fluoroplastic.

An additional benefit to this type of inductive proximity sensor is its ability to prevent any build up of weld slag.

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Information Sheet 7.1.1: Sensor; Design, Selection, Specification and Implementation

Is the sensing application in a high temperature environment?
Inductive proximity sensors typically include their silicon amplifiers and detection circuitry inside the sensor head
housing. These proximity sensors are called self-contained devices. Self-contained proximity sensors are
practical for most applications until environmental conditions begin to exceed the normal operating parameters for
a silicon-based circuit. Normal operating temperatures for silicon based circuitry is within the realm of -25 to 70C
(-13 to 158F). Under any temperature conditions beyond these ranges, the circuitry becomes more prone to
operating failure.

For temperature applications that exceed these requirements, look for inductive proximity sensors that use
separate amplifiers. With separate amplifier inductive proximity sensors, the sensor head contains the inductive
coil and little more. The intelligent amplifier and detection circuitry can be located safely away in a remote
environmentally controlled area. Such sensors can resist temperatures as high as 200C (392F).

Mounting Restrictions
When it comes to miniaturization, few components so strongly represent the micro-electronic revolution that has
occurred within the last 10 years as inductive proximity sensors. Today, the world’s leading manufacturer of
inductive proximity sensors can manufacture a 5.5mm X 5.5mm X 19mm, rectangular proximity sensor with an
extended sensing range of 1.6mm.

Does your application space constraints prohibit the use of an inductive proximity sensor with a
traditional cylindrical based body?
Inductive proximity sensors come in a wide variety of body types. Rectangular style inductive proximity sensors
range from the sub-miniature (5.5mm X 5.5mm X 19mm) to the flat pack style
(25mm X 10mm X 50mm) all the way up to the limit switch housing size (40mm X 40mm X
115mm). In the last case, the life of an inductive proximity sensor in limit switch housing will far outweigh the life
of a typical limit switch. Limit switch life is on the order of 300K cycles while the similarly shaped inductive
proximity sensor in limit switch housing can last up to 100K hours.
Other advances in inductive proximity sensor miniaturization include separate in-line amplifier type. Inductive
proximity sensors of this type come with sensing heads as small as 3mm in diameter and robotics cabling that
allow the sensor head to move if needed.

So have you considered the questions above and eliminated the need for the most popular types of
specialized inductive proximity sensors?
As a designer, you can then reliably fall back on the proven success of the traditional inductive proximity sensor.
Before you specify a particular inductive proximity sensor for your application, be sure to investigate the following
qualities for a long lasting and well-manufactured device.

Does the inductive proximity sensor in question have a strong enclosure?
Cylindrical proximity sensor’s barrel housing thickness varies from manufacturer to manufacturer.
The thicker the barrel housing of the Inductive Proximity Sensor, the less likely it will be to break due to
overzealous installation techniques or through incidental object collision.

Has the inductive proximity sensor been vacuum potted?
Most proximity sensors are potted, but poor potting is almost worse than no potting at all. The poorly potted
proximity sensors will have air bubbles trapped inside the devices that cause undue stressing which may lead to
PCB cracking and failure.

Does the cable have a proper strain relief?
An inductive proximity sensor with a cable that protrudes directly out of the potting material is susceptible to
breakage at the potting material-cable conjunction. A proximity sensor cable with this design also has a much
weaker pull force. If you are interested in a long life sensor, look for a strong, flexible strain relief on your Inductive
proximity sensor of choice.

Inductive Sensor Specification
In automation design, it is necessary for one to understand the precise technical definition of a component’s
behavior. The following definitions, if not the terminology itself, are unique to inductive proximity sensors.
Therefore, it is important to describe and comprehend definitions before implementation of the inductive
component into the application at present.

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Information Sheet 7.1.1: Sensor; Design, Selection, Specification and Implementation

Upon review an inductive proximity sensor data sheet displays many specifications that tell a designer how to
implement the inductive device for the purposes of detecting a specific object.

Standard Detectable Object
When an inductive proximity sensor’s data sheet refers to a standard detectable object, it tells the specified
shape, size, and material which is used as the standard to examine the performance of the proximity sensor. This
understanding is important because the detection distance of the inductive proximity sensor differs according to
the shape and material of an object. Typically, the standard detectable object will be an iron plate with a thickness
of 1mm and height and width of equal length to the diameter of the inductive sensor.

Detection Distance
Detection distance is the position at which the inductive proximity sensor operates when a “standard detectable
object” is moved in front of the sensor in a defined manner. For an Inductive proximity sensor with an end (or
“front”) detection surface, the detection distance is determined by aligning the center line of the Inductive sensor

with the center line of the standard detectable object. The standard detectable object is moved towards the face

of the inductive proximity sensor until the proximity sensor changes states and the detection distance is

determined.

One of the issues that is examined when considering the detection distance of an inductive proximity sensor is the
target material’s capacity for conducting electricity. Materials that are highly conductive make poor targets for
traditional inductive proximity sensors. Also, the target’s thickness will have an influence of its detection. Thin

materials are easier for an inductive proximity sensor to detect then thick materials.

If one reviews the principles of operation for an inductive proximity sensor shown earlier in this article, the material
conductance and thickness factor to detection distance behavior falls in line with the technology of the inductive
proximity sensor. A conductive material will disperse Eddy circuits and not allow them to build up thus making it
harder to detect. A thin material due to its lack of ability to move current when compared to a thicker material
causes a buildup of Eddy currents, which allow for higher detection distances.

Reset Distance

The reset distance refers to the distance at which the inductive proximity sensor releases its output when the
standard detectable object is removed from its field of detection. The difference in distance between the detection
distance and the reset distance is called the “Distance differential.” Typically, the distance differential is from 3%
to 10% of the overall detection distance. The distance differential is incorporated into the design of the inductive
proximity sensor to prevent the proximity sensor from having its output chatter due to noisy environments or
detectable object vibrations.

Today’s quality inductive proximity sensors can have trigger points that are repeatable to 1/10,000ths of an inch.

Designers be must aware, however, that desired detectable object must approach the face of the inductive sensor
to trip the output and then be removed from the inductive sensor’s field of detection by the distance differential

before another precise object

trigger can occur.

Setting Distance
The setting distance describes the distance at which the inductive proximity sensor will trigger an output with the
standard detection object even if the detection distance has been decreased due to temperature or voltage
fluctuations. When implementing an inductive proximity sensor, the detectable object to sensor face calculations
should begin with the setting distance specifications.

Not every design, however, will have the luxury of detecting the standard detection object described in the
inductive proximity sensor data sheet’s engineering section. In the cases of irregular object detection, the

detecting distance cannot be estimated from the engineering data.

In these cases, an operational check with the sample object is required. Take the detection object in question and
approach the inductive proximity sensor until the output changes state. The distance determined is the “detection
distance” of the target object and inductive proximity sensor combination.

The Setting Distance for the target object can then be calculated by the following formula: New
Setting Distance = (Detection Distance obtained by test with target object) X (Setting Distance of the standard
detectable object)/(Standard Detection distance of the standard detectable object).

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Information Sheet 7.1.1: Sensor; Design, Selection, Specification and Implementation

In other words, the object’s setting distance is proportional to the standard detecting target’s detection distance to
setting distance ratio.

Inductive Sensor Implementation
Mounting requirements must be considered when implementing the inductive proximity sensor into your design
otherwise you may encounter reduced sensing distance, false triggering, or non-detection of the target.

Influence of surrounding metals
When an inductive proximity sensor is mounted into its sensing position, it is important to consider the effects of
the mounting hardware itself and other metallic objects that may be present in the area of the sensor.

For the shielded type of inductive proximity sensor, the device can be embedded into a metallic mounting fixture
up to the point when the sensor’s face is at an equivalent height as the mounting surface. This embedded mount
protects the inductive sensor from mechanical damage due to incidental contact with the target object. It is not
recommended that a shielded inductive proximity
sensor be recessed into a metal mounting surface. Objects, materials, or opposing surfaces that are not to be
detection objects should remain clear of the Inductive sensor’s face by a factor of 3
times the sensor’s standard detection distance.

For the unshielded type of inductive proximity sensor, the device cannot be completely embedded into a metallic-
mounting fixture. Due to its extended sensing distance, the unshielded inductive proximity sensor is susceptible to
the influences of surrounding metals. One does not only need to consider that objects, materials, or opposing
surfaces must remain clear of the sensor’s face by a factor of 3 times the sensor’s standard detection distance. In
addition, one must consider that the inductive proximity sensor must be clear of surrounding metals by its size
(diameter in the case of a cylindrical proximity sensor) in every direction with a depth clearance of 2 times its
standard detection distance.
Failure to meet the inductive sensor’s clearance requirements can lead to false detection or reduced sensing
distances.

Mutual interference
When multiple inductive proximity sensors are mounted in close proximity to one another either alongside or in an
opposing directions to another inductive proximity sensor, either inductive sensor can be subject to an effect
called mutual interference.

Mutual interference is created when the field of a proximity sensor couples with the detection coil field of another
closely mounted proximity sensor. The result can create an inductance that can result in the generation of a beat
frequency in one or both of the sensors. This, in turn, causes the output of the proximity sensor to chatter (switch
on and off erratically).

Mutual interference problems can be insidious due to their erratic nature. A sensing application where Inductive
sensors are mounted side by side and closer then a manufacturer’s mutual interference distance specifications
can actually perform seamlessly at one time and then suddenly display signs of chattering and false detection at
another time.

Specifications for separation distance of proximity sensors that are mounted side by side can vary from sensor
body type and by manufacturer. Always examine and adhere to the manufacturer’s specification distances for
mounting inductive proximity sensors to avoid potential mutual interference problems.
If your application and sensing requirements demand your inductive proximity sensors to be mounted closer
together, consider the following tips. The selection of a shielded type of inductive sensor allows for closer
mounting. Of course, one could also specify a miniature inductive sensor. The smaller size means smaller
sensing distances and less probably for mutual interference.

In addition, some manufacturers of inductive proximity sensors offer alternate frequency types.
Alternate frequency inductive sensors oscillate their magnetic coils at different cycle rates than their standard
inductive proximity sensor counterparts. This prevents the inductive coupling that leads output chattering.

Lastly, if close sensor mounting cannot be avoided, the inductive proximity sensors can be multiplexed. Turning
off and on alternate inductive proximity sensors and taking alternate reads can be a quick solution to a mutual
interference problem provided that your application accounts for the response time hit.

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Information Sheet 7.1.1: Sensor; Design, Selection, Specification and Implementation

Inductive Proximity Sensors: Conclusion
More inductive proximity sensors are sold worldwide then any other sensing technology. The inductive proximity
sensor’s durability, life, and resistance to dust and harsh environments have made it the designer’s prime choice
in sensing technology. Newly armed with the knowledge of selection techniques, specification nuances and
implementation considerations will help you overcome the most common inductive proximity sensor application
pitfalls.

Contributors
1. Guerrino Suffi
2. http://www.rselectronics.com/SEO/Selecting_Prox.pdf

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Operation Sheet 7.1.2: Guide for Sensor Installation

Learning outcomes:
7 Inspect and test the repaired mechatronics devices and systems
Learning Activity:
7.1 Operating Instructions on Capacitive sensor.

INSTRUCTIONS FOR CORRECT INSTALLATION

THESE SENSORS ARE NOT MADE FOR SAFETY APPLICATIONS AND FOR SAFETY
DEVICES. THEREFORE THEY CANNOT BE USED TO PREVENT INJURIES TO PERSONS,
DAMAGES, INDUSTRIAL DAMAGES, ACCIDENT.

PRELIMINARY NOTE

 An instruction is indicated by "►":
Example: ►Check whether the unit operates correctly.

 A reaction to the action is indicated by ">":
Example: > Yellow LED lights.

IMPORTANT NOTE
Non-compliance can result in malfunctions or interference.

INFORMATION
SUPPLEMENTARY NOTE

1 SAFETY INSTRUCTIONS
 Please read the product description prior to set-up of the unit. Ensure that the product is suitable for your
application without any restrictions.
 The unit conforms to the relevant regulations and EC directives.
 Improper or non-intended use may lead to malfunctions of the unit or to unwanted effects in your
application.
 That is why installation, electrical connection, set-up, operation and maintenance of the unit must only be
carried out by qualified personnel authorized by the machine operator.

2 FUNCTIONS AND FEATURES
 The capacitive sensor detects without contact metals, almost all plastics, glass, ceramics, wood, paper,
oils, greases, water and all hydrous materials and indicates their presence by providing a switched signal.

3 INSTALLATIONS

3.1 Notes on flush and non-flush installation
 In case of flush installation of non-flush units the sensor properties change and the sensor can remain
permanently switched (loss of function).

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Operation Sheet 7.1.2: Guide for Sensor Installation
►Observe the free space around the sensing face.

1: flush
2: non-flush
Sn: nominal sensing range (see data sheet)
d: unit diameter

►Observe the minimum distances when installing several sensors of the same type.

Sn: nominal sensing range (see data sheet)
d: unit diameter

►Observe the minimum distance when installing the type KD

1: sensor type KD (only non-flush installation)
The distances need to be determined by the user in his application.

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Operation Sheet 7.1.2: Guide for Sensor Installation

4 ELECTRICAL CONNECTION
The unit must be connected by a qualified electrician. The national and international regulations for
the installation of electrical equipment must be adhered to.

►Disconnect power.
►Connect the sensor according to the indications on the type label.

Note: use a miniature fuse according to the technical data sheet, if specified.
Recommendation: check the safe functioning of the unit after a short circuit.
4.1 Wiring

Figure 1: 2-Wire Technology

Figure 2: 3-Wire Technology

1: miniature fuse (for AC units)
2: negative switching
3: positive switching

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Operation Sheet 7.1.2: Guide for Sensor Installation

4.2 Programming
4.3 Type KI (with connector)
4.3.1 Programming via the link in the connector

1: programmed as normally open (factory setting)
2: programmed as normally closed
4.3.2 Programming via wiring (KGE - DC PNP/NPN)

4.4 Type KDE - two-wire technology
4.4.1 Programming via wiring (KDE - AC/DC PNP/NPN)

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Operation Sheet 7.1.2: Guide for Sensor Installation

4.5 Type KDE - three-wire technology
4.5.1 Programming via wiring (KDE - DC PNP/NPN)

Core colours of ifm sockets:
BN (brown), BU (blue), BK (black).

4.6 Type KIE / KGE
4.6.1 Programming via the wire link

1: programmed as normally open (wire link closed, factory setting)

2: programmed as normally closed (wire link open)

►Use an appropriate tool to disconnect the wire link.

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Operation Sheet 7.1.2: Guide for Sensor Installation

5 OPERATING AND DISPLAY ELEMENTS
5.1 Example type KB

1: LED
2: potentiometer

6 SETTINGS

6.1 Sensing range

►Set the sensing range via the potentiometer using the enclosed screwdriver.

1: increase the sensing range
2: reduce the sensing range

7 OPERATIONS
 Check whether the unit operates correctly. Bring about a sensor response by taking suitable measures.
 Display by LEDs:
 LED yellow out: switching output disabled
 LED yellow on switching output enabled

8 MAINTENANCE, REPAIR, DISPOSAL

The operation of the unit is maintenance-free. To ensure a correct function:
 Keep the sensing face and a clear space, if any, free from deposits and foreign bodies.
 It is not possible to repair the unit.
 After use dispose of the unit in an environmentally friendly way in accordance with the applicable national
regulations.

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Operation Sheet 7.1.2: Guide for Sensor Installation

9 DEFINITIONS

Active zone
Area above the sensing face in which the sensor reacts to the approach of the target.

Output function
Normally open: object within the active zone - output switched.
Normally closed: object within the active zone - output blocked.
Programmable: choice between normally closed or normally open.
Positive switching: positive output signal (to L-).
Negative switching: negative output signal (to L+).

Power-on delay time
The time the sensor needs to be ready for operation after application of the operating voltage (in the millisecond
range).

Hysteresis
Difference between the switch-on and the switch-off point.

Leakage current
Current for the internal supply of 2-wire units, also flows through the load when the output is blocked.

Current consumption
Current for the internal supply of 3-wire DC units.

Switch point drift
Shifting of the switch point owing to changes of the operating conditions (e.g. temperature, pressure, air humidity).

Short-circuit protection
Sensors which are protected against excessive current by means of a pulsed short-circuit protection. The inrush
current of incandescent lamps, electronic relays and low resistance loads may cause this protection to cut in and
turn the sensor off!

Operating voltage
The voltage range in which the sensor functions safely. A stabilised and smoothed direct voltage should be used!
Take into account residual ripple!

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Job Sheet 7.1.3: Guide Questions in Sensor Selection

Learning outcomes:
7. Inspect and Test the repaired Mechatronics Devices and Systems
Learning Activity:
7.1 Selecting the appropriate sensor for a given application.

With all the different technologies available how can the correct sensor be chosen for a specific application? It
starts with knowing the proper questions to ask. With a few general questions answered, the huge selection of
available sensors can be narrowed considerably.

Here is a list of 10 questions that should be addressed in selecting the proper sensor for an application. This does
not claim that with this list the exact sensor will be chosen. However, if these questions answered properly, you
will be in the ballpark and well on your way to a sensor solution.

GUIDING QUESTIONS PARAMETERS BEING CONSIDERED

1. How are you already sensing the target and why do  Sensor Application
you want to change?
 Sensor Technology
2. What are the characteristics of the target?
a. Color  Sensor Technology
b. Shape
c. Size  Power Source
d. Material
 Mounting Installation
3. How close can you get to the target?
a. Close range, Inductive and Capacitive  Background Suppression
b. Longer range, Photoelectric or - Determine if technology such as Background
Ultrasonic) suppression photoelectric is needed
- Or can background be used as a reflector for
4. What is the available voltage supply? Retroreflective Ultrasonic.
a. AC - Also can background interfere with inductive or
b. DC capacitive

5. What are any other materials around the side of the  (Frequency, speed necessary for reliable detection)
sensing face and how close?  Sensing Output
a. flush
b. non-flush mounted - Normally Open or Normally Closed
- Light Operate or Dark Operate)
6. Without the target in place, describe the  Wiring Installation
background and can anything be mounted there? - Maximum load current sensor can handle or, is
a. Distance
b. Color an interface needed
c. Shape - PNP or NPN?
d. Material
 Environmental Rating
7. Speed target passes the sensor and how often?

8. Do you want an output with the target present or
not?

9. What is the load?

10. Describe the characteristics of the environment the
sensor is in?
a. Dirty / Clean
b. Temperature
c. Moisture

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Work Sheet 7.1.4: Sensor

Learning outcomes:
7. Inspect and Test the repaired Mechatronics Devices and Systems
Learning Activity:
7.1 Selecting the appropriate sensor for a given application.

Instruction:

Column A contain a drawing of a proximity limit switch. In the bracket to the left of the drawing, write the
letter of the correct part name in Column B which fits the encircled number. You may use a letter in
column B once, more than once, or not at all.

Column A Column B
A Free Position
( )1 B Pretravel
( )2 C Release Position
( )3 D Differential Travel
( )4 E Operating Position
( )5 F Over-travel
( )6 G Idle Position
( )7

H Pre-travel

Figure 1: Proximity Limit Switch

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