Description          Magnetic speed sensors use a magnet as the sensing element or sensed target in order to capture rotational or linear speed. Typically, they are used as gear-tooth speed sensors or incorporated into stroboscopes or tachometers. Types Technology choices for magnetic speed sensors include magnetoresistive, inductive, variable reluctance, and Hall Effect. Magnetoresistive sensors incorporate the resistance of the...
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Q & A on Magnetic Speed Sensors

We asked our users for their input on Magnetic Speed Sensors. Here are the results of 118 users familiar with Magnetic Speed Sensors.

Who Took Our Poll? | Design Trends | Applications and Use | Features | Buying Advice

Who Took Our Poll?Top

Design TrendsTop

Q:
What new technologies are influencing magnetic speed sensor design?
15 answers
Answers:

Different rare earth metals and other metals that make up the magnets for the speed sensors, to control size and price and temperature range of operation. Green energy.

~Engineering, Design, hampton, VA

1_For power generation in Gas generators the valve of the Gas inlet is controlled depending on the crank shaft's speed measured using the speed sensor which is quite sensitive because an incorrect value might result in fire or explosion! 2_ For NDT testing of large metal pipes sensors with a convergent electro-magnetic beam are required to detect the crack precisely. 3_ Increasing range for application on baggage processing to identify whether the baggage has metallic objects above a threshold... I would name it as 'thresholding sensors.'

~Fawaz A, Student, Karachi, Pakistan
Accuracy in very low speed detection. Required in my industry for (train) roll-away protection.
~Brad G, Engineering Consultant, Pittsburgh, PA
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Q:
From your perspective, which companies are creating the most innovative magnetic speed sensors?
17 answers
Answers:
Allegro, Infineon, Motion sensors, Chen Yang
~Engineering, Design, NIS, Serbia-Montenegro
Hamlin, Honeywell, Continental
~Engineer
The two ones that I am familiar with are AI-Tek Instruments and Jaquet.
~Paulo P, Marketing/Sales, Sao Paulo SP
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Applications and UseTop

Q:
What are some of the applications you have used magnetic speed sensors for?
33 answers
Answers:
Belt conveyor, bucket elevator, screw conveyor, coupled drive systems, weighing systems, positioning systems or motion control, physical test equipment.
~Ken S, Control Systems Analyst, Redding, CA
As speed inputs to Automatic Train Control systems on Mainline and Commuter Rail.
~Brad G, Engineering Consultant, Pittsburgh, PA
Speed monitoring of multiple applications with portable power tools. The power tools were AC powered DC powered and Gasoline.
~Joe N, Research & Development, Anderson, SC
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Q:
Please share with us any “non-standard” applications that magnetic speed sensors have been used for.
6 answers
Answers:

Model airplane engine synchronization - using speed sensors and simple logic to synchronize multi-engine scale model applications.

~Dave W, Director of Engineering, Gravenhurst, Canada

Magnet encapsulated in flow meter rotor exposed to 100 deg C of oil which has to activate hall switch mounted on flowmeter body when distance between magnet & hall sensor is 4 to 5 mm.

~Vijay C, Manufacturer, Pune, India
Elongation of construction elements (beam, etc.) according to temperature condition (these is magnetic sensor, not necessary speed sensor).
~Bozidar S, Engineer, Croatia

Q:
Do you know of any disastrous mistakes that occurred due to the incorrect usage of magnetic speed sensors?
7 answers
Answers:

Poor electrical installation, poor grounding practices, poor mechanical installations, too far from target, too close to target, too much vibration, too much heat.

~Ken S, Control Systems Analyst, Redding, CA
Damage to toothed wheel and MPU due to incorrect gap.
~Paul F, Engineering Consultant, Brush, CO

Over rating for temperature especially with respect to long term usage.

~Engineer
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FeaturesTop

Q:
What would your design or feature "wish list" be for this product?
19 answers
Answers:

Hall switch should operate with lowest possible Gauss value (weakest rare earth magnet of 3mm dia operating at 100 deg C where magnet is about to lose its magnetic field strength).

~Vijay C, Manufacturer, Pune, India

Faraday effect sensor, velocity range 0 - 5 m/s, low cost OEM device, standard instrumentation interface, non-corroding in saltwater, OK at 20 bar, compact, reliable, robust, calibrated.

~Project Manager

- completely robust (dust proof, water proof, shock prof etc ) - its wire should not break as much as you stretch it... I learned it at an auto-parts manufacturing plant where the wire used to get broken because of hardening over time. - range should be 1 cm at-least and directly focused in-front of the head, not around the head. - easily installable - pnp/npn type selector switch should be there on the sensor - sensitivity control knob should be there on the sensor - digital output etc

~Fawaz A, Student, Karachi, Pakistan
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Q:
Is there any advice you want to share with users to help them avoid common errors in selection or usage of magnetic speed sensors?
11 answers
Answers:
Use active speed sensors to obtain speed very near zero. Non active sensors can only measure as low as the signal to noise ratio.
~Brad G, Engineering Consultant, Pittsburgh, PA

Yes, talk to an application engineer before selecting a gear for pulse generation. Also make sure that the speed range meets the demand.

~Paulo P, Marketing/Sales, Sao Paulo SP

Follow manufacturer's guidelines for installation and range to target. Use proper grounding techniques to avoid noise and false signals.

~Ken S, Control Systems Analyst, Redding, CA
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Buying AdviceTop

Q:
Do you have any advice for people relative to buying or using magnetic speed sensors?
10 answers
Answers:
Many people like the ease of installation and low cost of capacity style proximity transducers or the precision of encoders but these sensors are not appropriate for harsh environments encountered in process industries. Magnetic sensors are overlooked by many instrumentation engineers, while they are the best choice for their robustness.
~Paulo P, Marketing/Sales, Sao Paulo SP
Gear misalignment, worn teeth on the gear, warped gear, etc. can give false speed readings. We have even seen a problem with a toothed gear slipping on the shaft and certain speeds. Make sure the gear is keyed to the shaft.
~Brad G, Engineering Consultant, Pittsburgh, PA

Develop thorough requirements specifications - pay particular attention to environmental specs (temperature, shock, exposure to solvents, etc.).

~Dave W, Director of Engineering, Gravenhurst, Canada
Once gapped with a toothed wheel, rotate the wheel to be absolutely sure it will not hit. Lessons learned!
~Paul F, Engineering Consultant, Brush, CO
Yes, always measure the size of the sensor suitable for their application and then order.
~Fawaz A, Student, Karachi, Pakistan
Always pick a product that the user is capable of using.
~Hank A, Technical Support, Santa Ana, CA
De-rate the manufacturer's temperature limits.
~Engineer
Use established manufacturers/vendors.
~Ken S, Control Systems Analyst, Redding, CA
I.Universal Operational Voltage.
~Govindasamy Sivaraj G, Technical Support, Bangalore, India
To choose specialists.
~Bozidar S, Engineer, Croatia


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