ファクトリーオートメーション(FA)
プロセスオートメーション(PA)

Fault Repair/FAQ


Frequently asked questions about using magnetic field sensors are looked at in this section.


Why Should I Use a Magnetic Field Sensor at All? Will a (Limit) Switch not Suffice for my Application?

Magnetic field sensors offer many advantages over traditional mechanical switches. In particular …

Comparison Magnetic Field Sensor Mechanical (Limit) Switch
Operation:    
Fast signal processing The electrical output signals can undergo further processing directly in electronic circuits. Issues a mechanical signal, which is then transmitted electrically, hydraulically, pneumatically, or mechanically as required.
Noncontact detection Operation without touching the objects being measured. Operation only possible with mechanical contact: objects to be measured can be manipulated or obstructed.
Quick detection Quick detection and thus short response and switching times, i.e., high switching frequencies are possible. The mechanical sequence takes time and sets narrow limits on the maximum switching frequency.
Maintenance-free operation (except Reed contacts) There are no moving contacts that can become contaminated or worn. Mechanical contacts can become contaminated and worn over time. The contact transition resistances can change unpredictably.
Reliable signal generation The electronic output prevents contact bounce. Contact bounce may occur at signal output.  As a result, a mechanical contact may supply multiple switching pulses per switch event.
Low energy consumption Very small switching currents are also possible. The contact resistance and the risk of oxidation of the contact surface mean that a certain minimum current is necessary.
Setup:    
Simple integration into an application
No calculation of the start-up curve is necessary. The start-up angle and start-up path must be calculated. Depending on the direction of actuation, different mechanical versions of the switch lever are required.
Service life:    
Wear-free operation (except Reed contacts)
The freedom from wear means that the switch points remain stable over time.
 
The number of switching cycles therefore does not affect the sensor service life.
Mechanically moving parts of the switch are subject to wear and lead to switching errors.
 
This means that the switching rate limits the switch service life.
Possible applications:    
Applications with little space Extremely compact designs are possible. There are structural limits to the implementation of compact designs.
Standard designs,
special designs as required
One design available for use in different applications requiring different movements.
 
Numerous sensor designs are available. 
Different applications require completely different designs or various sensing elements (rollers, tappets, levers, etc.).

 


The Damping Magnet Is Not Detected, What Am I Doing Wrong?

Check all settings, properties, and distances relating to the sensor and damping element. In particular ... 

Sensor properties

  • Operating distance: The operating distance can be found in the product technical data and the product marking.
  • Switching element function: Check whether the specified switching element function is being observed: NPN or PNP? NC contact or NO contact?
  • Electric voltage (if applicable): The supply voltage must be within the specified ranges, see Technical Data.

Damping magnet

  • Carrier material of the damping magnet: Magnetically conductive carrier material can influence the operating distance of the sensor. 
  • Size: Does the operating distance relate to the correct damping magnet?
  • Sensor-damping magnet relationship: Is the damping magnet moving past the sensor and at what speed? →  Take the response curve into account: The switching frequency must not be exceeded. Is the magnet oriented toward the sensor or is it transverse to the sensor axis?

Why Is the Sensor Switching Too Early?

Check the sensor and the ambient conditions for possible interference.
In particular ...

  • Switching element function: Check whether the specified switching element function is being observed: NPN or PNP? NC contact or NO contact?
  • Installation conditions: Are the sensor and magnet mounted flush or nonflush according to the specifications in the technical data? Have the specified installation conditions been correctly implemented?
  • Interference from other materials near the sensing face: Check whether there is any other magnetic material nearby.

Is the Selected Sensor Chemically Resistant to a Particular Cleaning Agent, Coolant, or Lubricant?

Unfortunately, we cannot give a definitive answer to this question.

This is because the composition of cleaning agents, coolants, and lubricants, i.e., the formulation, is known only to the relevant manufacturer. Lubricating oils usually contain additives, which can change the chemical behavior of the lubricating oil, even in small quantities. Even if the sensor housing material specified in the technical data promises to be oil-resistant, the additives can make the lubricant aggressive as a whole.

It is therefore essential to carry out your own tests to check chemical compatibility. Please note that the manufacturer of a cleaning agent, coolant, or lubricant can change its formulation without notice. This can cause a combination of materials that has worked for a long period of time to suddenly stop working.

Must Existing EC-Type Examination Certificates Issued in Accordance with EU Directive 94/9/EU Be Replaced by New EU-Type Examination Certificates, which in turn Cite EU Directive 2014/34/EU?

The new EU Directive 2014/34/EU provides clear information in this regard under Article 41, paragraph 2, and states that EC-type examination certificates issued under EU Directive 94/9/EU remain valid.

Citation 2014/34/EU
Article 41 Transitional Provisions

(1) Member States shall not impede the making available on the market or the putting into service of products covered by Directive 94/9/EC which are in conformity with that Directive and which were placed on the market before April 20, 2016. 

(2) Certificates issued under Directive 94/9/EC shall be valid under this Directive.

 

How Do I Recognize the Sensor Connection Type?

The various connection types can be quickly identified by referring to the type code.

Connection Type Sensor Identification (cf. Type Code)
Fixed cable Sensor without connection identifier at the end of the order designation.
Connector One of the following connector identifiers at the end of the order designation: "V1", "V3"

 


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Magnetic Field Sensors

Take a look at the range of Pepperl+Fuchs magnetic field sensors.