C-107
Contents
1. Recommended mounting hole sizes for cylindrical switches Mounting hole M8 8 2 0 1 M12 12 2 0 1 18 2 0 1 30 2 0 1 M18 M30 Mounting hole shape When mounting a cylindrical type switch avoid mounting it in an elongated hole or on a U shaped bracket Since some teeth on the toothed washer would not be in contact with the surface the switch might come loose Refer also to User s Manual and Specifications of each model2. a plot of the sensing range when the size of one side of the target object is fixed and target thickness changes Thickness of target object and sensing distance typical Target object Al Sensing distance mm Thickness mm If the target object is 1 mm or more thick a standard sensing dis tance can be obtained which will hardly change regardless of the thickness of the target object If the target object is less than 1 mm thick the sensing distance will change according to the thickness of the target object Note particularly that if the target object is non magnetic metal e g copper aluminum the sensing distance in creases with decreased thickness and at about 0 01 mm thick is almost the same as for magnetic metal e g iron 3 Voltage drop characteristics diagram This indicates the output voltage V of the proximity switch in proportion to load current A when the proximity switch is ON This is called output voltage drop it also indicates the output voltage V when the proximity switch is turned OFF in proportion to load current A when the proximity switch is ON The value obtained by subtracting this output voltage value from the power voltage is called load voltage drop Voltage drop characteristics typical OFF Voltage drop V 1 10 100 Load current mA 4 Off state current characteristics diagram This indicates how off state current which flows when the proximi ty
3. in selecting the mounting location Proximity switch Target object E GENERAL CHARACTERISTICS 1 Sensing area diagram This is a plot of points at which the proximity switch is actuated measured from the edge of the standard target object when a standard target object approaches parallel to the sensing face typical FL7M 15_16 Standard target object Iron 30 x 30 x 1mm Standard target object X Sensing distance Y mm 15 10 5 0 5 10 15 Sensing distance X mm 2 Sensing distance according to material and size of object The sensing distance varies according to the material and size of the target object Sensing distance according to material amp size of object typical 3 0 Iron E 20 x 0b z SUS S 1 5 x2 oO B 3 1 0 rass D Aluminum ao Copper 0 0 5 0 10 0 15 0 20 0 25 0 Size of one side of target object d mm Generally the sensing distance on non iron targets is shorter than that for iron targets The sensing distance is almost the same if the target object is made of iron and is larger than a standard target object if the target object is not made of iron or its dimensions are smaller than the standard target object measure the actual sensing distance with the target object while referring to the graph above and mount the proximity switch so that the usable sensing distance is 70 or less of this value Below is
4. TECHNICAL GUIDE FOR PROXIMITY SWITCHES Mi DEFINITIONS Proximity switch includes all switches that detect the presence of a metallic object approach ing the sensing face or near the sensing face without mechanical contact There are detection systems that use the eddy currents that are generated in metallic target objects by electromagnetic induction most Azbil proximity switches systems that detect changes in electrical capacity when approaching the target object etc The Japanese Indus trial Standards JIS define them as inductive and capacitive proximity switches respectively Detection principle of high frequency oscillation proximity switches High frequency oscillation proximity switches detect magnetic loss due to eddy currents that are generated on a conductive surface by an external magnetic field An AC magnetic field is generated on the detection coil and changes in the impedance due to eddy currents gener ated on a metallic object are detected Other systems include aluminum detecting switches which detect the phase component of the frequency etc W Azbil PROXIMITY SWITCH CATEGORIES The target object and switch form what appears to be a transformer like relationship The transformer like coupling condition is replaced by impedance changes due to eddy current losses The impedance changes can be viewed as changes in the resistance that is inserted in series with the target object The following table summari
5. directly enters the switch Noise Radiant noise Ingress of high frequency elec tromagnetic waves directly into switch from power line etc After countermeasures e Insert a shield copper plate between the switch and the noise source e g a switching power supply e Separate the noise source and the switch to a distance where noise does not affect operation Shield plate copper 4 O V Noise Switch source Oov Before countermeasures Noise enters from the power line Normal mode noise Power line noise Ingress of electro magnetic induction ene After countermeasures noise from the Insert a capacitor e g a film capacitor switching power noise filter supply e g ferrite core or isolation transformer or varistor in the power line Insert a capacitor etc ssn E Surface roughness smoothness Do not make the mounting surface excessively rough or exces sively smooth Recommended examples Ra 1 6 3 2 or 6 3 Avoid application of too much oil etc on contact surfaces of screw nut washer and mounting areas It might change the fric tion coefficient of the surface resulting in damage to the proximity switch or loosening of the screw Washer In mounting cylindrical switch it is recommended to insert the toothed washer to the opposite side of the tightening nut The toothed washer does not scratch the nut or mounting panel main taining stable tightening
6. e cable bend radius differs according to the model be sure to check the precau tions for each model Routing of wiring Do not run wires to the proximity switch together with power lines Surge noise can cause damage or malfunction Wire leads to the proximity switch independently or in a separate wiring duct Grounding of switching regulator If a commercially available switching regulator is being used ground the frame ground terminal to prevent switch malfunction due to switching noise Noise Countermeasures for noise depend on the path of noise entry frequency components and wave heights Typical measures are as given in the following table Type of noise Noise intrusion path and countermeasures Before countermeasures Noise enters from the noise source through the frame metal frame metal Inverter Common mode noise inverter noise Common mode noise applied be tween the equip ment frame and the V and 0 V lines respectively After countermeasures Ground the inverter motor to 1002 or less 2 Ground the noise source and the power supply 0 V side through a capacitor 3 Insert an insulator plastic rubber etc between the switch and the equipment frame metal Insert an insulator O V Inverter witc motor A Oov Noise 1 Noise l umet Linn NOI OM Equipment g frame metal Before countermeasures Noise propagates through the air from the noise source and
7. e fluctuation frequency etc AC Selecting Resistive load Non contact control system X ig supply type Inductive load Relay solenoid etc AC e Steady state current inrush current Load Operating reset voltage current Output Lamp load Switching current e Steady state current inrush current L Off state current Open close frequency Voltage drop 5 Operating frequency DC proximity switches have a higher operating frequency than AC ones Use DC models if high speed response is required 6 Target object moving speed To select a switch for a target object moving at high speed use the following calculation based on the operating frequency operating time of the proximity switch length of the target object and dis tance to the target object 1 Ds Dt Db Dt sec Rt St St Rt Operating frequency Hz Ds Width of sensing area mm Dt Length of target object mm Db Distance between target objects mm St Speed of target object mm s Select a switch that fits the characteristics of the target object Dt Ds m St LLLLILLLLLALLLALA LLLA LLG Target object Proximity switch Mi PRECAUTIONS FOR USE Design of load circuits Load short circuit If the proximity switch is connected to an AC power supply without passing through a load the proximity switch will be damaged Be sure to connect a load If the switch is connected to a DC load it will not be damaged as almost all model
8. en output is OFF This is referred to as off state current Since off state current is present a voltage equivalent to load resistance x off state current is exerted on the load even when the proximity switch is OFF Note that this will cause reset failure of the load if the off state current exceeds the load reset voltage Ex FL7M DC 2 wire shielded switch O D M8 0 55 mA max Switching current This refers to the minimum current required by the proximity switch and the maximum current that the proximity switch can switch Maximum switching current The maximum current that is allowed to flow to the output circuit when the proximity switch is ON If the current is greater the load short circuit protection circuit will be activated or the proximity switch will be damaged Minimum switching current The minimum required current that flows to the internal circuits when the proximity switch is ON At a lower current the switch will not operate If the load resistance is too large and results in the load current not satisfying this minimum switching current connect a bleeder resistor in parallel to the load to lower the total load resis tance Ex FL7M DC 2 wire shielded switch O D M8 3 to 100 mA Voltage drop This is the voltage that is generated across the output and O V ter minals DC 3 wire proximity switch or the switch output terminals DC 2 wire proximity switch Note that the load sometimes cannot be actuated
9. n distance sensing distance Reference point Proximity switch Generally the sensing distance of a proximity switch is measured by this perpendicular actuation method Parallel operation Sensing distance __ Reset OFF Differential travel Actuated ON Standard target object SPCC a Reference axis Reference point Proximity switch Expressed as the measured distance from the reference point when the standard target objects moved parallel to the sensing face This distance depends on the moving path distance from the reference point so it can be expressed as an operating point locus sensing area diagram Rated sensing distance This is the distance to the target object from the sensing face at which the proximity switch is actuated when a standard target object approaches in a direction that is perpendicular to the sensing face Usable sensing distance This is the distance to the target object from the sensing face at which the target object can be stably detected when it approaches from a direction that is parallel to the sensing face Normally this is 70 to 80 of the rated sensing distance Rated sensing distance Note Iron target of standard target object dimensions or more Usable sensing distance a _ Sensing face Target object Standard target object A target object that is used for measuring the
10. onnect a bleeder resistor in series to the load so that a current larger than the minimum switching current flows to the switch Preventing proximity switch damage from inrush current When you connect a load such as a lamp or motor that has a large inrush current the switching element in the proximity switch may become damaged or deteriorate Accordingly connect such loads via a relay Operation at power ON After the power is turned ON it takes a fixed delay time tens of milliseconds until the proximity switch is ready for sensing If the load and the proximity switch use different power supplies be sure to turn the proximity switch ON before turning the load ON Protecting the sensing face of the proximity switch The sensing face of the proximity switch is made of resin For this reason contact with the target object or chips etc hitting the sensing face may cause switch damage Attach a protective cover if there is a risk of chips hitting the sensing face Protecting lead out wires Cover lead out wires with flexible tubing Recommended cable length For cable extensions use at least 0 3 mm wire and keep length to within 100 m Preventing influence from surrounding metal Metal other than the target object near the proximity switch influ ences sensing characteristics Mount proximity switches away from surrounding metal by the recommended distances Example of DC 2 wire cylindrical long distance no polarity swi
11. oximity switch 2 2 Environment The environmental resistance of the proximity switch is better than that of other types of switches However investigate carefully before using a proximity switch under harsh temperatures or in spe cial atmospheres Temperature Highest or z Temperature influence and lowest values high temperature use humidity existence of low temperature use direct sunlight etc L need for shade etc Water oil Need for water resistance Atmosphere iron powder or or oil resistance other need for special chemicals L explosion proof structure E Intensity Need for durability ARA duration _ mounting method Explosive atmosphere Do not use the switch in atmospheres where there is a danger of explosion Use an explosion proof switch Aluminum or cast iron chips If aluminum or cast iron chips accumulate on the sensing head use the FL7M A series aluminum immunity proximity switch Spatter If the proximity switch is subject to spatter use spatter guarded models 3 Switch body type Select a body type that is suited to the location where the proximity switch is to be used 4 Electrical conditions Verify the electrical conditions of the control system to be used and the electrical performance of the proximity switch Proximity switch Selecting m the power supply type p DC voltage fluctuation maximum current DC OWE AC voltag
12. s have a self contained load short circuit protection circuit However in the case of DC 2 wire proximity switches the switch will be damaged if it is short circuited and also connected with the leads reversed even though the switch has a self contained load short circuit protection circuit Series or parallel connection Connection varies according to whether it is an AC 2 wire or DC 2 wire type Refer to the precautions for each of these types Preventing reset failure of the load Off state current from the proximity switch causes a voltage equiv alent to load resistance x off state current to be exerted on the load If this voltage exceeds the load reset voltage a reset failure will occur Be sure to check that this voltage is lower than the load reset voltage before using the proximity switch or to connect a bleeder resistor in series to the load to lower the total load resis tance When switching of a relay load is not possible Voltage drop occurs across switch output terminals even if the proximity switch is OFF For this reason the load voltage may be insufficient with some types of relays For example when the FL7M DC 2 wire type proximity switch is connected to a 12 V relay load the voltage drop will be 3 3 V which may prevent the relay from being switched When the load current is too small to actuate the proximity switch If the load current is smaller than the minimum switching current of the proximity switch c
13. sensing distance Nor mally this is a square iron plate cold rolled steel sheet SPCC of stan dard size Generally the size of the standard target object is the mini mum target object size so that a fixed sensing distance can be achieved Accordingly the proximity switch is actuated at approximate ly the rated sensing distance if the target object is larger than the stan dard target object and of the same material and thickness i V N S Standard target object Proximity switch Ex FL7M DC 2 wire shielded switch O D M8 Iron 8 x 8 mm t 1 mm He 9 t Differential travel This is the difference between the distance sensing distance at which a standard target object approaching perpendicular to the sensing face actuates the proximity switch and the distance reset distance which the standard target object must move away for the switch to return to OFF This is expressed as a percentage of the sensing distance OFF r i g Sensing g distance 1 g 4 l l D I 17 14 Reset i distance Ex FL7M DC 2 wire shielded switch O D M8 15 max of sensing distance Difference travel Mutual interference This refers to the state in which performance and characteristics e g sensing distance are influenced when two or more switches are positioned close to each other Off state current In the case of 2 wire proximity switches a slight current flows to ac tivate internal circuits even wh
14. switch is OFF changes in proportion to changes in the power voltage Off state current characteristics typical 1 5 FL7L 2L16HL _ e FL7M 3L6HL FL7M 7L6HL FL7M 10L 6HL Off state current mA Power voltage V Mi SELECTION OF PROXIMITY SWITCHES The following introduces typical points to take into consideration when selecting a proximity switch 1 Operating conditions Sensing distance The usable sensing distance is about 70 of the rated sensing distance However to ensure reliable sensing it is advisable to take factors such as drift in proximity switch performance mean dering of target objects and conveyor undulation and allow a cer tain degree of margin when using the switch On the other hand for high resolution using a model with a short sensing distance will provide better results 2 Environmental conditions 2 1 Surrounding metal When there is a metal object other than the target object near the sensing face of the proximity switch the sensing performance of the proximity switch will be affected and the apparent sensing dis tance will increase and become unstable When the proximity switch is flush mounted in metal use a shielded switch with a sens ing coil whose sides are covered with metal If you use an unshield ed switch be sure to mount it away from surrounding metal by at least the recommended distance Target object Sensing distance Surrounding metal Pr
15. tch Catalog listing A mm B mm FL7M 4116 2 5 5 5 12 f go FL7M 8L16 3 5 6 5 24 FL7M 1516 6 10 45 Shaded areas indicate surrounding metal other than the target object A Distance from sensing face of proximity switch to mounting surface Case of mounting included hexagonal nut in front B Distance from surface of iron plate to sensing face of proximity switch C Distance from surface of iron plate to center of proximity switch when A 0 Preventing mutual interference When mounting proximity switches in parallel or facing each other mutual interference may cause the switch to malfunction Maintain at least the space indicated in the specifications Example of DC 2 wire cylindrical long distance no polarity switch pN CHL Catalog listing A mm FL7M 4L16 25 FL7M 8Ll6 40 FL7M 15L16 90 Overtightening of screws When mounting proximity switches tighten screws etc at the al lowable tightening torque or lower Be sure to use included toothed washers when mounting cylindrical switches Cable pullout strength Do not pull on the cable with excessive force For details on pullout strength refer to the specifications Location Do not use proximity switches outdoors or in locations where they will be splashed with oil or water or exposed to chemicals e g or ganic solvents acids alkalis or their vapors Cable bend radius R Do not bend the cable excessively Since allowabl
16. when output is ON as this voltage drop occurs Ex FL7M DC 2 wire shielded switch O D M8 3 0 V max Operating frequency This is the maximum number of sensing per second in which output can be made proportional to repeated approaches of the target object to the sensing face Operating frequency expresses re sponse speed Proximity switch 2M 1 2 ran t2 ETI M Sensing distance Standard target object Non metal Temperature drift This indicates how much in the sensing distance changes when the operating temperature differs from the standard 25 C Ex FL7M DC 2 wire shielded switch O D M8 10 max of sensing distance for the 25 to 70 C range Power voltage drift This indicates how much in the sensing distance changes when the power voltage differs from the rated power voltage Ex FL7M DC 2 wire shielded switch O D M8 10 max of sensing distance with a 15 voltage fluctuation Shielded With a shielded switch magnetic flux is concentrated in front of the switch and the sides of the switch coil are covered with metal The switch can be mounted by embedding it into metal Proximity switch Target object Unshielded With an unshielded switch magnetic flux is spread widely in front of the switch and the sides of the switch coil are not covered with metal This model is easily affected by surrounding metal objects magnetic objects so care must be taken
17. zes Azbil proximity switches by actuation method structure built in or separate amplifier sensing head shape and shielding Series name DC2 wire FL7M DC3 wire FL7M DC2 wire FL7M A Categorization by actuation method High frequency oscillation DC2 wire FL2R S DC2 3 wire FL2R V APT DC3 wire DC2 wire FL2 DC2 3 wire DC2 wire FL2F Categorization by structure Built in amplifier Amplifier Relayed Cylindrical Categorization by sensing head shape Shielded Cyl Sq Unshielded High frequency oscillation The switch is turned ON and OFF when a metal object approaches the sensing face coil Most Azbil proximity switches are this type Built in amplifier Resists influence from electrical noise because the sensing coil is integrated with the oscillation circuit Amplifier Relayed The sensing coil and the oscillation circuit are separate This allows the sensing face to be smaller Cylindrical Round sensing face Square Square shaped sensing face Shielded The sides of the sensing coil are covered with metal This structure is robust and less likely to be affected by surrounding metal Unshielded The sides of the sensing coil are not covered with metal This allows the sensing distance to be made longer Mi GLOSSARY Perpendicular operation Reset OFF L Standard target object SPCC Actuated ON Differential travel Retur
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