BEI Sensors Speed and Position Sensors Selection Guide
PRODUCT SELECTION GUIDE
Speed and Position Sensors for Extreme Applications
Built for
Extreme
Environments
About BEI Sensors 3
Major Industries Served 4
Sensor Technologies 6
Excellence in
Design and
Engineering
Rugged
and
Reliable
As an industrial consumer, you require the highest levels
of quality and reliability in the products you purchase.
It is critical that devices operate dependably day after day in some of the most
extreme conditions imaginable. BEI Sensors understands these needs and—
backed by decades of experience—designs sensors that offer uncompromising
quality and performance. BEI Sensors upholds a standard of excellence in our
products, customer service experience, and commitment to being your preferred
partner for position sensors. We fully understand that your complete satisfaction
is key to our success.
Extreme Environments 8
Hazardous Areas 9
Optical Encoders 10
Magnetic Encoders and
Hall Effect Sensors 18
Potentiometers 22
Sensor Support Products 24
SwiftComm Interface 26
Product Adaptablity 27
Mission
Critical
Applications
BEI Sensors provides reliable position, speed and inclination sensing products
for mission-critical and extreme environment applications in the industrial,
military/aerospace and off-road equipment markets worldwide. Our products
utilize the latest optical, magnetic and potentiometric sensing technologies. The
comprehensive product line includes absolute and incremental encoders, Hall
effect sensors, as well as rotary and linear potentiometers. Specialized products
for harsh environments include those certified for use in hazardous areas,
wash-down environments, and applications where they are exposed to extreme
vibration, shock and operating temperatures. In addition to an extensive range
of standard product offerings, we have the ability and expertise to make product
adaptations and create completely customized sensing solutions to suit even the
most challenging applications.
BEI Sensors’ experienced customer service staff offers an outstanding level of
service, both before and after the sale. Our order department quickly answers
questions on order status, pricing and availability, or helps specify a unit to meet
your exact requirements. Our highly trained applications staff helps with any
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technical needs—whether it’s assistance with an interface or questions about
crossing over a competitor’s part number. The BEI Sensors engineering team
also consults on advanced technical issues. We consistently provide this high
The Utmost
in Service
and Support
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level of service to an active customer base of thousands of companies. Everyone
at BEI Sensors works toward a common goal—to provide the most reliable
products and deliver the best customer service found anywhere.
BEI Sensors is the preferred position sensors partner
to leading companies around the globe.
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Serving the Position Sensing Needs of these Major Industries
These days, engineers have to do more with fewer resources. BEI Sensors helps by acting as an extension
of your engineering team. Our application and design engineers assist with everything from creating custom
sensors to troubleshooting installations. We are more than just a supplier. We partner with our customers to
help make their operations run more easily and efficiently.
Mining
In mining applications, BEI Sensors helps with everything from shaft elevator
control and ore cart positioning to the control of heavy equipment such as
excavators and earthmovers. Sensors in this environment have to withstand
high shock and vibration, along with extremely dusty and wet conditions. BEI
manufactures rugged products designed to deliver optimum performance in
these demanding operations. In addition, when hazardous area certifications
are required, BEI Sensors offers a number of products certified by UL,
CENELEC, LCIE and MSHA rating agencies.
Metal Manufacturing
There are few harsher, more corrosive environments than a steel
mill. Molten steel is cast into large slabs at blistering temperatures.
Water from line sprayers hits freshly poured slabs, creating clouds
of steam. Every piece of equipment is exposed to continuous
humidity. BEI speed and position sensors are engineered to
withstand this unforgiving environment. Encoders are available with
stainless steel housings and other protective coatings to prevent
corrosion and rust. High IP ratings are offered to resist pressurized
spray, condensation, and dust. BEI Sensors’ products are built tough
to operate reliably in these severe conditions.
Oil and Gas
Sensors used in the oil and gas industry must withstand high temperature
and pressure, potentially explosive locations, and extreme shock and vibration,
along with exposure to chemicals, dirt and moisture. Position sensors perform
crucial functions in oil and gas applications and must operate reliably day in
and day out to ensure an optimized yield. BEI Sensors is well aware of these
unique upstream, midstream, and downstream requirements and has designed
products that feature uncompromising quality and performance. Hard anodized
housings, gross leak tests, extended temperature ranges and a variety of
sealing options are available on numerous BEI products. BEI Sensors also offers
one of the largest selection of hazardous area rated products, including UL
Class I Division 1 and 2, and Class II Division 1 and 2, and ATEX Zone 1 and
Zone 2 (See page 9). A variety of communication protocols including Profibus,
CANopen and DeviceNet are also offered.
Off-Road Equipment for Construction and Agriculture
BEI Sensors’ products have stood the test of time, providing a
high degree of reliability and performance, while withstanding
the severe conditions posed by off-road and industrial vehicle
applications. These demanding applications rely on precise
position sensing and redundant safety for steering and wheel
systems, steer-by-wire systems, gear sensing, pedal and
throttle control, hand acceleration, valve and control logging,
cabin controls and more. Whether exposed to dirt, extreme
temperatures, or moisture, the rugged construction of BEI
Sensors products ensures their accurate and reliable operation
day after day, year after year.
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Heavy Motors
BEI Sensors has supplied high quality, rugged encoders to heavy motor
manufacturers for decades. Heavy motors are found in all types of harsh
industrial environments, and require extremely rugged feedback devices.
BEI’s products have the proven reliability needed for successful operation in
these environments. If a motor is needed for use in a hazardous area, simply
select one of BEI’s large catalog of UL and ATEX pre-certified products. They
provide a drop-in feedback solutions that are ready to operate in hazardous
areas worldwide. Custom product adaptations are also available for seamless
integration into any motor design. BEI’s design engineers are always on hand
to provide any amount of customization, from simple shaft and connector
modifications to designing a new sensor around your exact requirements.
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Cranes
Cranes are critical pieces of equipment for a variety of industries
around the world. The environments where they operate are
almost as diverse as the materials they move. Whether it’s
loading and unloading cargo in unforgiving seaports, or handling
material on a factory floor, cranes require reliable feedback
solutions to do their job properly and safely. BEI Sensors
offers a variety of position sensors and a real-time wireless
interface system rugged enough for the toughest environmental
conditions, while providing the position and speed feedback
needed to move materials with precision and accuracy.
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Choosing the Right Sensor Technology
BEI offers a variety of speed and position sensing technologies. It’s important to choose one that’s suited to
your particular application. The sensor’s operating environment, required degree of precision, output type,
speed, and physical configuration all must be considered. The descriptions of the different technologies on
these pages will help guide you in choosing the optimal speed and position sensing technology.
Optical Technology
RATINGS ON FIVE KEY CRITERIA
Ruggedness
PRecision
sPeed
TemPeRaTuRe
emi ResisTance
Optical sensing technology uses the interruption of light to
detect movement. Optical encoders have an internal code disc
with opaque lines or patterns that are rotated in the path of a
light source, typically from an LED. The code disc acts like a
shutter to alternately block (OFF) or unblock (ON) the light to an
internal photodetector. The photodetector senses the alternating
light beam, which the encoder’s electronics convert into an
electrical signal. This signal is passed to an external control
system through the encoder’s output.
Optical sensing technology is the most precise and offers
the highest resolution of the position sensing technologies.
It is also resistant to environmental magnetic interference
and, when enclosed in a metal housing, highly resistant to
EMI. BEI Sensors’ optical encoders are well sealed, allowing
them to operate in harsh and dirty environments. They are
also highly resistive to shock and vibration, and are capable
of withstanding a 50 g, 11 msec shock pulse and 20 g’s of
vibration (5 to 2000 Hz). This level of robustness makes BEI
encoders well-suited for most industrial applications.
BEI optical encoders are ideal for numerous types of
industrial processes, such as oil well drilling, machine control,
agricultural machinery, web process control, robotics, elevators,
construction equipment, cranes, motor feedback and any
closed loop control systems.
Magnetic / Hall Effect Technology
RATINGS ON FIVE KEY CRITERIA
Ruggedness
PRecision
sPeed
TemPeRaTuRe
emi ResisTance
Magnetic sensing technology uses changes in magnetic fields
to detect movement. There are two ways magnetic technology
is integrated into the BEI Sensors offerings, digital encoders and
analog Hall effect position sensors. Magnetic encoders use a
disc that has been magnetized with multiple, north/south pole
pairs that are in the form of radial lines or patterns. In place of
a photodetector, magnetic encoders use an ASIC designed to
detect alternating north and south poles as the disc is rotated
past it. As the ASIC senses the change in magnetic poles,
internal electronics convert it into a digital electrical signal that
is then passed through the device’s output.
In the Hall effect sensor configuration, the internal disc is
magnetized with a single pole pair. The disc is attached to
the sensor’s rotor which is then coupled to the motion being
measured. The sensor’s ASIC is designed to detect the change
in the direction of the magnetic field as the disc rotates above
it. These changes in magnetic field are converted to an analog
signal that is ratiometric (proportional) to the angle of the
rotating disc.
Hall effect sensors are typically used to resolve angular position
with an analog output while magnetic encoders are most often
used to detect rotational speed and direction with a digital
output. Magnetic encoders tend to have lower resolution
and precision than their optical counterparts and are more
susceptible to environmental magnetic interference. However
Potentiometric Technology
RATINGS ON FIVE KEY CRITERIA
Ruggedness
PRecision
sPeed
TemPeRaTuRe
emi ResisTance
Potentiometric sensing technology is available in one of three
configurations: wirewound, conductive plastic and hybrid.
Wirewound potentiometers are comprised of a resistive element
(coil) and a contact spring (wiper).The coil is made from a very
fine wire that is precisely wound onto a mandrel. The wiper, a
specially engineered precious metal contact, wipes across the
wound coil. The coil is fixed internally to the sensor’s housing
and the wiper is attached to the sensor’s rotor which in turn is
coupled to the motion being measured. A voltage is applied
across the coil and the coil becomes a voltage divider. As the
motion being measured rotates the wiper across the energized
coil, a voltage proportional to the rotational position can be read
between the coil and the wiper. The output changes in discrete
steps as the wiper moves across the individual coil windings.
Conductive plastic potentiometers are very similar to wirewound,
except that the wiper moves across a conductive plastic
element rather than a coil. The conductive plastic element is
comprised of a substrate and a resistive epoxy. In its pre-cured
state this resistive epoxy material is referred to as “ink”. The ink
is applied to a substrate using a silk screening process. Once
both products are ideal for operation in very high temperatures
and environments with extreme shock.
Ideal applications for magnetic encoders include wind energy,
tree harvesting, traction motors for rail equipment and
pavement profiling. Hall effect sensors excel in steering,
pedal and throttle for off-road equipment, dancer controls in
web processing, flow control valves and elevator door opener
applications.
cured, the ink acts very similarly to the coil in a wirewound
potentiometer, with the advantage of having a very uniform,
smooth surface. This surface provides a more continuous output
and longer life as compared to a wirewound potentiometer.
As its name implies, hybrid potentiometers use a combination of
the two previous mentioned configurations, using a wirewound
coil coated with the conductive plastic material.
Wirewound potentiometers provide the highest accuracy of the
three configurations and dissipate power very well; however
because of the metal-to-metal contact between the wiper and
coil, wirewounds have a shorter operating life. Conductive
plastic potentiometers provide the highest resolution or output
smoothness and have a higher operational life than wirewounds,
however it is more difficult to get the high linearity (accuracy)
available from a standard wirewound potentiometer. Hybrid
potentiometers are able to combine the best aspects of both
other configurations. A hybrid potentiometer has a better
ability to dissipate power (over conductive plastic pots) and has
improved resolution or output smoothness (similar to conductive
plastic potentiometers). The use of conductive plastic material
gives hybrids a longer operating life over wirewounds.
Potentiometers in general have several benefits including
small package size and weight, resistant to electromagnetic
interference (EMI), temperature stability and are able to work at
very high (300C max) and low (-55°C) operating temperatures.
Ideal applications include aircraft control surfaces, in-cylinder
hydraulics and oil field downhole measuring.
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Hazardous Area ProductsSensors for Extreme Environments
C US
C US
C US
C US
C US
BEI understands the challenges posed by extreme environments and has developed an extensive line of
products designed to operate in the harshest conditions imaginable. The icons below each represent a
particular environmental extreme. They are used in the product selection pages of this guide (pages 8–25) as
a quick visual indicator of which products are designed to operate in which extreme environment condition
.
Wet If a sensor has to operate in a liquid environment, it must have adequate sealing and the appropriate IP rating (as
a measure of ingress protection) to guard against contamination. Products rated IPX5 are protected from “water jet” liquid
ingress. An IPX6 rating indicates protection from “powerful water jets.” An IPX7 rating means the product can be immersed
in water up to 1 meter for 30 second durations. BEI products with this icon are rated IPX6 or above.
Dirty/Dusty
operate in the constant presence of dust. The majority of BEI products are rated to this level and this icon represents this
rating. Products with the lower IP5X rating are considered as only “dust protected,” which means that dust ingress is still
possible. IP5X rated products are recommended for environments where dust is only occasionally present.
Extended Temperatures
temperature range—typically 0 to +70°C. If your application requires operation in extreme temperatures (above or below
these ranges), BEI offers extended temperature options. Products with this icon have extended temperature ratings (beyond
their stated operating temperature) as a standard option.
High Shaft Load
sensors or potentiometers. Encoders have internal bearing structures that can carry some load. In applications that use
gears or drive belts, excessive radial (side) loading of the shaft can shorten bearing life. Encoders should be specified in
accordance with the anticipated radial loading. Typical maximum loads for industrial encoders are 5 to 40 lbs (22 to 178 N).
Ultra heavy-duty encoders are available to withstand heavier loads. Encoders with this icon can withstand high shaft loads
in the range of 40 to 300 lbs (178 to 1335 N). See individual product data sheets to determine actual maximum load.
Corrosive or Washdown
a corrosive environment. In food or medical-grade applications, where washdown may occur, an electroless nickel coating
or stainless steel housing is recommended. Products with this icon incorporate special finishes or housing material as a
standard option.
Hazardous Areas
potentially explosive environments. Products with this icon have certification for one of the following: explosion-proof, flame
proof, intrinsically safe, or non-incendive. Refer to the next page for complete information on hazardous area certifications.
BEI products with this icon are rated IP6X and are considered “dust tight,” meaning that they will
The majority of BEI Sensors products are rated to operate over a wide
For applications with shaft loading conditions it is best to use encoders over Hall effect
A hard anodized finish is recommended for sensors intended to operate in
Hazardous locations require equipment designed and certified to operate safely in
BEI Sensors offers a complete selection of UL and ATEX certified position sensing products. Certifications
include UL Class I Division 1 and 2, and Class II Division 1 and 2, as well as ATEX Zone 1 and Zone 2. The
tables on this page provide details on BEI Sensors products’ certifications. A variety of protection methods
are available. The four most common are described below.
Explosion Proof Construction
• Enclosure can withstand internal ignition and contain the
explosion without damage to the enclosure
• Heated gases from an explosion that pass through gaps or
joints in the assembly will be cooled sufficiently to not ignite
gases outside the housing
• Must be connected using gas-tight conduit
• Rated for Division 1 or Zone 1 installations
Flame Proof Construction
• Enclosure can withstand internal ignition of volatile
gas-to-air mixtures without damage to the enclosure
• Allows for termination using a certified cable gland
and cable
• Cannot be used for Division 1 hazardous areas
Intrinsic Safety
• Limits the maximum energy that can be delivered into the hazardous
location
• Has limitations on the amount of energy that can be stored within the
body of the device
•
Ensures that even in double fault condition, not enough energy is sup-
plied to or stored in the encoder which could create a spark or heated
surface to ignite gas, vapor, dust or fiber in the hazardous area
•
Must be used with Intrinsically Safe (IS) barrier. An IS encoder installed
without an IS barrier is not an IS system.
Nonincendive
• Assures no sparking or hot surfaces will occur in the device under
normal operating conditions (unlike intrinsically safe encoders which
are evaluated under fault conditions)
•
Acceptable in Division 2 and Zone 2 installations where explosive
agents are present only in abnormal operating conditions
Hazardous Environment Groups
Gas Groups Dust Groups
Class I Class II
Division 1 & 2 Zone 0, 1 & 2 Division 1 & 2
A (acetylene)
B (hydrogen) F (coal)
C (ethylene) IIB (ethylene) G (grain)
D (propane) IIA (propane)
IIC (acetylene &
hydrogen)
E (metals)
(Div 1 only)
European “Flame Proof” Approvals
CENELEC/ATEX
Encoder Type
GAMX, GEMX, CAMX, CEMX Ex d IIC T6
GAUX, GEUX, CAUX, CEUX, PAUX, PEUX Ex d IIC T6
Category 2,
Zone 1 and 21
North American “Explosion Proof”
& European “Flame Proof” Approvals
NEMA 7 U.S.,
Encoder Type
H38 (Standard) D
H38
(w/ Labyrinth Seal)
H40
HS52 II 2 G Ex d IIB T4 Gb C, D (US only)
SwiftComm Ex d IIC B, C, D E, F, G
Encoders with metal connector or conduit terminations are rated to EN 55011 and EN 61000-6-2.
For plastic connector, pigtail or shielded/jacketed cable terminations, consult factory
North American and European "Intrinsic Safety" Approvals
CENELEC/
ATEX
II 2 G Ex d IIB T4
Canadian
Standards Class
I, Div 1, Group:
C, D E, F, G
D
NEMA 7 U.S.,
Canadian
Standards Class II,
Div 1, Group:
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Shock and Vibration
The use of position sensors in high shock or vibration environments that are
not properly rated can result in output errors, reduced accuracy, or component failure. It is important to be aware of an
application’s expected shock and vibration and select a sensor rated for that environment. Products with this icon can
withstand greater than 100 g’s of shock or over 10 g’s of vibration. See individual product data sheets for maximum shock
and vibration ratings.
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North American and European
“Nonincendive” Approvals
Division 2,
Encoder Type
H20, H25, HS25, ES20, ES25,
HS35, HS45
PHU9
Groups:
A, B, C,
D, F & G
CENELEC/ATEX
Zone 2
Ex nA II T4
Encoder Type CENELEC/ATEX
H20, H25, ES20, ES25, H38,
H40, HS20, HS25, HS35,
HS45
IBM5, IHM5, IHO5, IBO5,
IHK5, IBK5, IHM9
U.S.,Canadian
Standards
Class I, Div1,
Group:
Ex ia IIC T4 A, B, C, D E, F, G IIC
Ex ia IIC T4
U.S., Canadian
Class II, Div 1,
Standards
Group:
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Canadian
Standards
Class I,
Zone 0,
Group:
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