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Inductive proximity sensors detect metal objects without physical contact through generating a magnetic field. They comprise an oscillator that creates an alternating magnetic field in front of its windings. When a metal object enters this field, it disturbs the oscillation and causes an output signal. Key advantages are contactless detection, high speeds, fast response, and durability in industrial environments due to having no moving parts.
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- 1. 31100 _Ver3.00-EN.fm/2 Schneider Electric Inductive proximity sensors enable the detection, without contact, of metal objects at distances of up to 60 mm. Their range of applications is very extensive and includes : the monitoring of machine parts (cams, mechanical stops, etc.), monitoring the flow of metal parts, counting, etc. Inductive proximity sensors are solely for the detection of metal objects. They basically comprise an oscillator whose windings constitute the sensing face. An alternating magnetic field is generated in front of these windings. Composition of an inductive proximity sensor 1 Oscillator 2 Output driver 3 Output stage When a metal object is placed within the magnetic field generated by the sensor, the resulting currents induced form an additional load and the oscillation ceases. This causes the output driver to operate and, depending on the sensor type, a NO, NC or NO + NC (complementary) output signal is produced. Detection of a metal object. / No physical contact with the object to be detected, thus avoiding wear and enabling fragile or freshly painted objects to be detected. / High operating rates. / Fast response. / Excellent resistance to industrial environments (robust products, fully encapsulated in resin). / Solid state technology : no moving parts, therefore service life of sensor independent of the number of operating cycles. Presentation 1 2 3 Inductive proximity sensors enable the detection, without contact, of metal objects at distances of up to 60 mm. Their range of applications is very extensive and includes : the monitoring of machine parts (cams, mechanical stops, etc.), monitoring the flow of metal parts, counting, etc. Inductive proximity sensors are solely for the detection of metal objects. They basically comprise an oscillator whose windings constitute the sensing face. An alternating magnetic field is generated in front of these windings. Composition of an inductive proximity sensor 1 Oscillator 2 Output driver 3 Output stage When a metal object is placed within the magnetic field generated by the sensor, the resulting currents induced form an additional load and the oscillation ceases. This causes the output driver to operate and, depending on the sensor type, a NO, NC or NO + NC (complementary) output signal is produced. Detection of a metal object. / No physical contact with the object to be detected, thus avoiding wear and enabling fragile or freshly painted objects to be detected. / High operating rates. / Fast response. / Excellent resistance to industrial environments (robust products, fully encapsulated in resin). / Solid state technology : no moving parts, therefore service life of sensor independent of the number of operating cycles. General Inductive proximity detection Advantages of inductive detection Principle of operation Inductive proximity sensors Object to be detected Object to be detected
- 2. 31100 _Ver3.00-EN.fm/3Schneider Electric ,,,,,,,, 0,81 Sn Sn 2 1 Sensing face H The operating zone relates to the area in front of the sensing face in which the detection of a metal object is certain. The values stated in the characteristics relating to the various types of sensor are for steel objects of a size equal to the sensing face of the sensor. For objects of a different nature (smaller than the sensing face of the sensor, other metals, etc.), it is necessary to apply a correction coefficient (see page 31100/14). 1 Detection threshold curves 2 “Object detected” LED Nominal sensing distance (Sn). The rated operating distance for which the sensor is designed. It does not take into account any va- riations (manufacturing tolerances, temperature, voltage, etc.). Real sensing distance (Sr). The real sensing distance is measured at the rated voltage (Un) and at rated ambient temperature (Tn). It must be between 90% and 110% of the nominal sensing distance (Sn) : 0.9 Sn ≤ Sr ≤ 1.1 Sn. Usable sensing distance (Su). The usable sensing distance is measured at the limits of the per- missible variations of the ambient temperature (Ta) and the supply voltage (Ub). It must be between 90% and 110% of the real sensing distance (Sr) : 0.9 Sr ≤ Su ≤ 1.1 Sr. Assured operating distance (Sa). This is the operating zone of the sensor. The assured operating distance is between 0 and 81% of the nominal sensing distance (Sn) : 0 ≤ Sa ≤ 0.9 x 0.9 x Sn. Square mild steel (Fe 360) plate, 1 mm thick. The side dimension of the plate is either equal to the diameter of the circle engraved on the active surface of the sensing face or 3 times the nominal sensing distance (Sn). The differential travel (H), or hyste- resis, is the distance between the pick-up point as the standard metal target moves towards the sensor and the drop-out point as it moves away. The repeat accuracy (R) is the repeatability of the usable sensing distance between successive operations. Readings are taken over a period of time whilst the sensor is subjected to voltage and temperature variations : 8 hours, 10 to 30 °C, Un ± 5 %. It is expressed as a percentage of Sr. General Inductive proximity sensors Standard metal target Operating zone Sensing distances Standard metal target Differential travel Repeat accuracy (Repeatability) Sa = H = course différentielle Terminology Su max. Sr max. Sn Sr min. Su min. Output ON Output OFF Sr max. + H Sn + H Su max. + H Sr min. + H Su min. + H Certain detection Assured operating distance Sensing distance Drop-out point Pick-up point Frontal approach Standard metal target
- 3. 31100 _Ver3.00-EN.fm/4 Schneider Electric BU BN –/+ +/– BU BN BU BN BU BK BN PNP + – + –BU BK BN NPN BU WH (NC) BK (NO) BN PNP + – + –BU BK (NO) WH (NC) BN NPN BK WH BN (NO), BU (NC) BU (NO), BN (NC) BN (NO), BU (NC) BU (NO), BN (NC) PNP + – + – WH BK NPN XS XS XS Corresponds to a proximity sensor whose output (transistor or thyristor) changes to the closed state when an object is present in the operating zone. Corresponds to a proximity sensor whose output (transistor or thyristor) changes to the open state when an object is present in the operating zone. Corresponds to a proximity sensor with 2 complementary outputs, one of which opens and one of which closes when an object is present in the operating zone. / Not polarity conscious, connections to + and – immaterial. / Protected against overload and short-circuit. / Not protected against overload or short-circuit. / 20…264 V supply, either or $. / Certain models protected against overload and short-circuit. / Protected against reverse supply polarity. / Protected against overload and short-circuit. / Protected against reverse supply polarity. / Protected against overload and short-circuit. / Protected against reverse supply polarity. / Protected against overload and short-circuit. Output signal (contact logic) 2-wire type 3-wire type 4-wire type, complementary outputs gr 4-wire type, multifunction, programmable NO NC NO + NC complementary outputs 2-wire $ non polarised NO or NC output 2-wire NO or NC output 2-wire 7 NO or NC output 3-wire $ NO or NC output PNP or NPN 4-wire $ NO and NC PNP or NPN 4-wire $ NO or NC, PNP or NPN General Inductive proximity sensors Outputs and wiring
- 4. 31100 _Ver3.00-EN.fm/5Schneider Electric 2-wire connection 3-wire connection + –S I + – + – S I These proximity sensors convert the approach of a metal object towards the sensing face into a current variation which is proportional to the distance between the object and the sensing face. 2 models available : / Dual voltage : $ 24…48 V / Single voltage : $ 24 V Output 0-16 mA for 3-wire connection and 4-20 mA for 2-wire connection The proximity sensors conforming to NAMUR (DIN 19234) recommenda- tions are electronic devices whose current consumption is altered by the presence of a metallic object within the sensing zone. Their small size makes them suitable for various applications in many sectors, notably : / Intrinsically safe / Non intrinsically safe Factory fitted moulded cable, good protection against splashing liquids. Example : machine tool applications. Ease of installation and maintenance. Flexibility, cable runs to required length. For characteristics of the various types of output, wiring precautions and terminology, see pages 31100/15 to 31100/ 18. Output 0-10 mA for 3-wire connection, and 4-14 mA for 2- wire connection. (hazardous areas). Sensors used with an NY2 intrin- sically safe relay/amplifier or a compatible solid state input which is suitably approved for intrinsi- cally safe applications. (normal safe areas). Sensors used with an XZD power supply/amplifier unit or a compa- tible (DIN 19234) solid state input amplifier. Analogue type NAMUR type Pre-cabled Connector Screw terminals Specific output signals Connection methods Additional information regarding outputs General Inductive proximity sensors Outputs and wiring
- 5. 31100 _Ver3.00-EN.fm/6 Schneider Electric LED indicators 2 1 1 2 1 2 1 2 1 2 All Telemecanique brand inductive proximity sensors incorporate an output state LED indicator. Output LED function table Certain block type XS7, XS8, XSD inductive proximity sensors incorporate a supply LED, in addition to the output LED. This provides instant verification of the supply state of the sensor . This LED, complementary to the output LED, flashes in the event of a short- circuit occurring on the load side of the sensor. It remains in the flashing state until the supply to the sensor is removed and the short-circuit rectified. This feature is particularly useful when switching inductive loads, which are prone to short-circuits. The short-circuit LED is incorporated in the following 2-wire type and $ short-circuit protected sensors : Ø 18 mm cylindrical type, Ø 30 mm cylindri- cal type and XSD block type. No object present Object present Short-circuit Short-circuit LED function table NO output NC output No object present LED Output state Object present LED Output state NO output NC output 1 Output LED 2 Short-circuit LED General Output LED Supply LED Short-circuit LED Inductive proximity sensors Specific functions
- 6. 31100 _Ver3.00-EN.fm/7Schneider Electric Output signal time delay 1 0 1 0 T T t t t t 1 0 1 0 T t t t t Block type XSC and XSD sensors incorporate a potentiometer adjusted 1 to 20 second output time delay. The outputs of these sensors are programmable (by links) and any of the following configurations are possible : / NO output contact - time delay when an object enters the operating zone, / NC output contact - time delay when an object enters the operating zone, / NO output contact - time delay when an object leaves the operating zone, / NC output contact - time delay when an object leaves the operating zone. The time delay is triggered as the object enters the operating zone and the output contact changes state only if the object is still present after the preset time (T) has elapsed. Application example : monitoring the flow of metal parts on a conveyor belt. Time that object is present in the operating zone The time delay is triggered as the object leaves the operating zone and the output contact changes state only if the preset time delay (T) elapses before another object enters the operating zone. Application example : monitoring for missing metal parts on a conveyor belt. Time that object is present in the operating zone General Inductive proximity sensors Specific functions Object present in operating zone Elapsed time delay NO output contact NC output contact Object present in operating zone Elapsed time delay NO output contact NC output contact Principle Time delay when object enters operating zone Time delay when object leaves operating zone
- 7. 31100 _Ver3.00-EN.fm/8 Schneider Electric Rotation monitoring 1 0 T (1) t t Fc Fr Sensors of the type generally known as “rotation monitoring” compare the passing speed of metal targets to an internal preset value. The trajectory of the target objects can either be rotary or linear. The moving part to be monitored is fitted with metal targets, aligned for detection by the sensor. The impulse frequency Fc generated by the moving part to be monitored is compared with the frequency Fr preset on the sensor. The output of the sensor is in the closed state for Fc Fr and in the open state for Fc Fr. Note : Following “power-up” of the sensor, the “rotation monitoring” function is subject to a start-up delay of 9 seconds in order for the moving part to run up to speed. (Sensors without this feature or with a delay reduced to 3 seconds are also available on request). Adjustment of Fr (1) Start-up time delay (contact closed during start-up period) Operating curve Detecting : / underspeed, / slip, / coupling breakage, / overload. Example : coupling breakage detection. General Inductive proximity sensors Specific functions Principle Operation Applications Output contact Fr adjustment potentiometer Metal target Non metallic material
- 8. 31100 _Ver3.00-EN.fm/9Schneider Electric Features of the various models 3 Sn 3 Sn 3 Sn 2 Sn e (mm) h(mm) General Cylindrical type - fast installation and setting-up, - pre-cabled or connector output, - small size facilitates mounting in locations with restricted access. Interchangeability, provided by indexed fixing bracket. When assembled, becomes similar to a block type sensor. Block type - direct interchangeability, without the need for readjustment, - output terminals, providing connection flexibility, - robustness. Sensors suitable for flush mounting - no lateral effect, but - reduced sensing distance. Sensors not suitable for flush mounting - sensing distance greater than that for flush mountable models, but - space required around the sensor to eliminate the effects of surrounding metal. / Standardflushmountable types : / Standard non flush mountable typesandincreasedrangetypes: Standard model Increased sensing range model e = 0, h = 0 - Ø 6.5, 8 12 mm e = 0, h = 0 - Ø 18 mm if : h = 0, e ≥ 5 e = 0, h ≥ 3 - Ø 30 mm if : h = 0, e ≥ 8 e = 0, h ≥ 4 Non ferrous or plastic material Types of case Suitability for flush mounting in metal Sensors suitable for flush mounting Sensors not suitable for flush mounting Mounting in conjunction with fixing bracket Inductive proximity sensors Mounting and installation precautions Mounting cylindrical type sensors on metal supports Metal Metal MetalMetal Metal Metal Detected objectDetected object Detected object Indexed fixing bracket Short case Form A case Form C Form D
- 9. 31100 _Ver3.00-EN.fm/10 Schneider Electric Mounting side by side, e ≥ 2 Sn Mounted face to face, e ≥10 Sn 1,5a 1,5 a a 3 Sn a a 1,5 a 3Sn 1,5a 2 a 2a a 2 a 2a 3 Sn a a 2 a 2 a 3Sn e e Mounting side by side, e ≥ 2 Sn Mounted face to face, e ≥ 10 Sn Mounting in the vicinity of metal masses, on one or more sides simultaneously. Mounting in an angle section Mounting in a U section Two sensors mounted too close to each other are likely to lock in the “detection” state, due to interference between their respective oscillating frequencies. To avoid this condition, minimum mounting distances given for the sensors should be adhered to. For applications where the minimum recommended mounting distances for standard sensors cannot be achieved, it is possible to overcome this restraint by mounting a staggered frequency sensor adjacent or opposite to each standard sensor. For information on staggered frequency sensors, please consult your Regional Sales Office. Correct mounting Not to be recessed Not to be mounted mounted adjacent to an angle Mounting block type sensors on metal supports Mounting distance between sensors General Inductive proximity sensors Mounting and installation precautions Metal Metal Metal Metal Metal Metal Metal Metal Metal Sensing face Sensing face Sensing face Metal Metal Metal Metal Metal Metal Sensing face Sensing face Sensing face Sensors suitable for flush mounting Sensors not suitable for flush mounting Standard sensors Staggered frequency sensors
- 10. 31100 _Ver3.00-EN.fm/1Schneider Electric 1 2 1 2 1 Insert the sensor into the bracket. 2 Secure sensor in fixing bracket using screw V. 3 The sensor is now rigidly clamped in the fixing bracket. Adjust the bracket/sensor assembly to ensure correct detection and positively secure the assembly using fixing screws F. The proximity sensor is positively indexed in position. If, for any reason, it is necessary to change the sensor : - loosen screw V and remove sensor, - insert the new sensor until it is against the stop. On tightening screw V, the new sensor will be indexed into the same position as the previous sensor. Plug-in body sensors enable mechanical separation of the part containing all the necessary electronics and the base part comprising the electrical connections and fixing points. This feature considerably reduces maintenance time in the event of a sensor being replaced, since only the electronic part need be replaced. The base part remains fixed in position, without the need of remaking the electrical connections or adjusting the settings. Sensors type XSB, XS7, XS8 and XSD feature a plug-in body. In addition, sensors type XS7 and XS8 incorporate a 5 position turret head. The head of the sensor can be rotated laterally throughout the 4 side detection quadrants or turned vertically for end detection. Maximum tightening torque for the various sensor case materials Consider the use of a protective sleeve and CNOMO adaptor. Brass Brass Stainless Plastic steel Diameter Short case Form A Form A All of sensor model model model models Ø 5 mm 1.6 1.6 2 – Ø 8 mm 5 5 9 1 Ø 12 mm 6 15 30 2 Ø 18 mm 15 35 50 5 Ø 30 mm 40 50 100 20 Torque indicated in N.m 1 2 3 1 Part containing sensor electronics 2 Base comprising electrical connections and fixing points General Inductive proximity sensors Mounting and installation precautions 1 CNOMO adaptor 2 Protective sleeve Screw VScrew F Screw F Mounting cylindrical type sensors using fixing bracket Plug-in body Turret head Tightening torque for cylindrical type sensors Protection of connecting cable
- 11. 31100 _Ver3.00-EN.fm/12 Schneider Electric All Telemecanique brand proximity sensors conform to the standard IEC 60947-5-2. / Operating temperature range of sensors : - 25…+ 70 °C. / Storage temperature range of sensors : - 40…+ 85 °C. Owing to the very wide range of chemicals encountered in modern industry, it is very difficult to give general guidelines common to all sensors. To ensure lasting efficient operation, it is essential that the chemicals coming into contact with the sensors will not affect their casings and, in doing so, prevent their reliable operation. Cylindrical type metal case sensors XS1-N, XS2-N and XS1-M, XS2-M offer very good resistance to oils in general, salts, essences and hydrocarbons. Also, sensor models XS1-M and XS2-M are particularly well adapted to severe environments such as machine-tool applications. Note : The cable used conforms to the standard NF C 32-206 and the recommendations of CNOMO E 03-40-150 N. Cylindrical type plastic case sensors XS3 and XS4 offer an excellent overall resistance to : - chemical products such as salts, haliphactic and aromatic oils, essences, acids and diluted bases. For alcohols, ketones and phenols, preliminary tests should be made relating to the nature and concentration of the liquid. - agricultural and food industry products such as animal or vegetable based food products (vegetable oils, animal fat, fruit juice, dairy proteins, etc.). The sensors are tested in accordance with the standard IEC 60068-2-27, 50 gn, duration 11 ms. The sensors are tested in accordance with the standard IEC 60068-2-6, amplitude ± 2 mm, f = 10…55 Hz, 25 gn at 55 Hz. Please refer to the reference/characteristic pages for the various sensors. IP 67 : Protection against the effects of immersion, tested in accordance with the standard IEC 529. Sensor immersed for 30 minutes in 1 m of water. No deterioration in either operating or insulation characteristics is permitted. IP 68 : Protection against the effects of prolonged immersion. The test conditions are subject to agreement between the manufacturer and the user. Example : Machine-tool applications or other machines frequently drenched in cutting fluids. Inductive proximity sensors have “TC” protective treatment as standard. Exceptions : - Increased range sensors : - 25…+ 50 °C, - Plastic case cylindrical type sensors (XS3-P and XS4-P) : - 25…+ 80 °C, - Metal case cylindrical type form A sensors (XS1-M and XS2-M) : - 25…+ 80 °C. Conformity to standards Resistance to temperature Resistance to chemicals in the environment Resistance to shock Resistance to vibration Degree of protection Protective treatment General Inductive proximity sensors Standards and certifications Parameters related to the environment
- 12. 31100 _Ver3.00-EN.fm/13Schneider Electric Proximity sensors type XS1, XS2, XS3, XS4, XSE, XS7 and XS8 are tested in accordance with the recommendations of the standard IEC 60947-5-2. / $ sensors : level 3 immunity except Ø 4 mm and Ø 5 mm (level 2). / and 7 sensors : level 4 immunity. IEC 61000-4-2 Level 3 : 8 kV Level 4 : 15 kV / $, and 7 sensors : level 2 or level 3 immunity. IEC 61000-4-3 Level 2 : 3 V/metre Level 3 : 10 V/metre / $ sensors : level 3 immunity. / and 7 sensors : level 4 immunity except Ø 8 mm (level 2). / Models with increased sensing range : level 2 immunity (at I = 50 mA). IEC 61000-4-4 / $, and 7 sensors : level 3 immunity except Ø 8 mm and smaller models : level 1 kV. IEC 60947-5-2 Level 3 : 2.5 kV Electrical insulation conforming to the standards IEC 61140 and NF C 20-030 concerning means of protection against electrical shocks. / Cylindrical type sensors / Block type sensors Level 3 : 1 kV Level 4 : 2 kV Standard version : UL, CSA except sensors with integral connector type XS/-////////LD, XS/-////////LA, XS/-////////C and XS/-////////T. The certifications pertaining to the various block type models are listed on their respective characteristic pages. General Resistance to electromagnetic interference Dielectric strength Insulation Product certifications Inductive proximity sensors Standards and certifications Parameters related to the environment Electrostatic discharges Radiating electromagnetic fields (electromagnetic waves) Fast transients (motor start/stop interference) Impulse voltages Class 2 devices )
- 13. 31100 _Ver3.00-EN.fm/14 Schneider Electric Correction coefficients to apply to the assured sensing distance Sa Kθ x Km x Kd x Kt 4.5 0.98 x 0.9 x 1 x 0.9 -25 0 20 50 70 1,1 0,9 1 Km 0,5 CuAU4GUZ33A37type 304 type 316 Steel Brass Alumin.Copper Iron Bronze Magnetic Stainless steel Lead 1Km 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,2 0,4 1 0,1 0,1 0,3 0,5 1,5 4 Sn3 Sn2 SnSn 1Kd 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 In practice, most target objects are generally made of steel and are of a size equal to, or greater, than the sensing face of the proximity sensor. To calculate the sensing distance for other application conditions the following parameters, which affect the sensing distance, must be taken into account : Note : The curves indicated below are purely representative of typical curves. They are given as a guide to the approximate usable sensing distance of a proximity sensor for a given application. Apply a correction coefficient Kθ, determined from the curve shown above. Apply a correction coefficient Km, determined from the diagram shown above. Typical curve for a copper object used with a Ø 18 mm cylindrical sensor. Special case for a very thin object made from a non ferrous metal. Typical curve for a steel object used with a Ø 18 mm cylindrical sensor. When calculating the sensing distance for the selection of a sensor, make the assumption that Kd = 1. Apply a correction coefficient Kd, determined from the curve shown above. In all cases, apply the correction coefficient Kt = 0.9. Example 1 : correction of the sensing distance of a sensor Proximity sensor XS7-C40FP260 with nominal sensing distance Sn = 15 mm. Ambient temperature variation 0 to + 20 °C. Object material and size : steel, 30 x 30 x 1 mm thick. The assured sensing distance Sa can be determined using the formula : Sa = Sn x Kθ x Km x Kd x Kt = 15 x 0.98 x 1 x 0.95 x 0.9, i.e. Sa = 12.5 mm. Example 2 : selecting a sensor for a given application Application characteristics : - object material and size : iron (Km = 0.9), 30 x 30 mm, - temperature : 0 to 20 °C (Kθ = 0.98), - object detection distance : 3 mm ± 1.5 mm, i.e. Sa max. = 4.5 mm, - assume Kd = 1. One possible choice is a Ø 18 mm cylindrical non flush mountable sensor, type XS2-M18PA370 (Sn = 8 mm). A sensor must be selected for which Sn ≥ = , i.e. Sn ≥ 5.7 mm. General Inductive proximity sensors Sensing distance correction coefficients Calculation examples Temperature °C Variations in ambient temperature Different types of object material Size of the object to be detected Variation of supply voltage Thickness of object in mm Side lengths of object in mm
- 14. 31100 _Ver3.00-EN.fm/15Schneider Electric Ir MA XU Ud V XU RrRa t Sensor operational at state 1 Supply voltage U on Sensor at state 0 Residual current (Ir) The residual current (Ir) corresponds to the current flowing through the sensor when in the “open” state. Characteristic of 2-wire type proximity sensors. Voltage drop (Ud) The voltage drop (Ud) corresponds to the voltage at the sensor's terminals when in the “closed” state. (Value measured at nominal current rating of sensor). Characteristic of 2-wire type proximity sensors. First-up delay The time (t) between the connection of the power supply to the proximity sensor and its fully operational state. Delays / Response time (Ra) : / Recovery time (Rr) : Check that the voltage limits of the proximity sensor are compatible with the rated voltage of the a.c. supply used. d.c. source : Check that the voltage limits of the proximity sensor and the acceptable level of ripple, are compatible with the supply used. a.c. source (comprising transformer, rectifier, smoothing capacitor) : The supply voltage must be within the operating limits specified for the proximity sensor. Where the voltage is derived from a single-phase a.c. supply, the voltage must be rectified and smoothed to ensure that : - The peak voltage of the d.c. supply is lower than the maximum voltage rating of the proximity sensor. Peak voltage = nominal voltage x √2 - The minimum voltage of the d.c. supply is greater than the minimum voltage rating of the proximity sensor, given that : ∆V = (I x t) / C ∆V = maximum ripple : 10 % (V), I = anticipated load current (mA), t = period of 1 cycle (10 ms full wave rectified for a 50 Hz supply frequency), C = capacitance (µF). As a general rule, use a transformer with a lower secondary voltage (Ue) than the required d.c. voltage (U). Example : 18 V to obtain $ 24 V, 36 V to obtain $ 48 V. Fit a smoothing capacitor of 400 µF minimum per proximity sensor, or 2000 µF minimum per Ampere required. Note : Certain models have increased operating limits. / short case models XS1-N, XS2-N, XS3-P, XS4-P (10…38 V) : can be supplied from full wave rectified and smoothed 24 V, / form A case 3-wire type models XS1-M, XS2-M, XS3-P, XS4-P (10…58 V): can be supplied from full wave rectified 24 V. The time delay between entry of an object (standard metal target) into the operating zone of the proximity sensor and the subsequent change of output state. This parameter limits the speed and size of the object. The time delay between an object (standard metal target) leaving the operating zone, in which it is being detected, and the subsequent change of output state. This parameter limits the interval between successive objects. Terminology Power supplies Inductive proximity sensors Specific aspects of electronic sensors General Inductive proximity sensors Specific aspects of electronic sensors Proximitysensors for a.c. circuits ( and 7 models) Proximitysensors for d.c. circuits
- 15. 31100 _Ver3.00-EN.fm/16 Schneider Electric Types of output Connection in series / / PNP + – NPN + – U supply n sensors These proximity sensors are wired in series with the load to be switched. Because of this they are subject to : - a residual current (in the open state), - a voltage drop (in the closed state). For polarised (polarity conscious) $ proximity sensors, the supply polarities must be observed. For non polarised (not polarity conscious) $ proximity sensors, the supply polarity and load connections to the + or - sides are immaterial. Advantages : - The proximity sensors can be wired in the same way as mechanical limit switches. - For and 7 models, they can be connected to either positive (PNP) or negative (NPN) logic inputs. No risk of incorrect connections. But : Check the possible effects of residual current and voltage drop on the input device being controlled (pick-up and drop-out thresholds). These proximity sensors comprise 2 wires for the d.c. supply and a third wire for transmission of the output signal. - PNP type : switching the positive side to the load, - NPN type : switching the negative side to the load. The programmable, universal sensors provide a choice of function, either : PNP/NO, PNP/NC, NPN/NO or NPN/NC. Note : Connection can only be made to a single load. Also, it is imperative that a discharge diode be incorporated when using an inductive load. The output LED indicator is wired for NPN operation (output ON : LED illuminated, output OFF : LED off). Therefore, for PNP operation the LED signalling is reversed. Advantages : - Programmable output signal, no residual current, low voltage drop. - NO + NC versions, for solid state input coincidence control (4-wire type). - Programmable models, reduced stock levels. But : Certain models must only be used with their designated PNP or NPN type of logic input. The following points should be taken into account : / Series wiring is only possible using sensors with wide voltage limits. / When in the open state, each sensor will share the supply voltage, i.e. : (based on the assumption that each sensor has the same residual current value). U sensor and U supply must remain within the sensor’s voltage limits. / If only one sensor in the circuit is in the open state, it will be supplied at a voltage almost equal to the supply voltage. / When in the closed state, a small voltage drop is present across each sensor. The resultant loss of voltage at the load will be the sum of the individual voltage drops and therefore, the load voltage should be selected accordingly. U sensor = 2-wire type 3-wire type 2-wire type proximity sensors Inductive proximity sensors Specific aspects of electronic sensors Electrical installation of electronic sensors General
- 16. 31100 _Ver3.00-EN.fm/17Schneider Electric This connection method is not recommended. Correct operation of the sensors cannot be assured and, if this method is used, tests must be made before installation. The following points should be taken into account : / Sensor 1 carries the load current in addition to the no-load current consumption values of the other sensors connected in series. For certain models, this connection method is not possible unless a current limiting resistor is used. / When in the closed state, each sensor will produce a voltage drop and, therefore, the load voltage should be selected accordingly. / As sensor 1 closes, sensor 2 will not operate until a certain time “T” has elapsed (corresponding to the first-up delay) and likewise for the following sensors in the sequence. / “Flywheel” diodes should be used when the load being swit- ched is inductive. The following points should be taken into account (2 and 3-wire types) : / When the mechanical contact is open, the sensor is not supplied. / When the contact closes, the sensor will not operate until a certain time “T” has elapsed (corresponding to the first-up delay) The use of proximity sensors wired in parallel, either between themselves or together with mechanical contacts, is not recommended. Should one of the sensors be in the closed state, the sensor in parallel will be “shorted-out” and no longer supplied. As the first sensor passes into the open state, the second sensor will become energised and will be subject to its first-up delay. The configuration is only permissible where the sensors will be working alternately. This method of connection can lead to irreversible damage of the units. No specific restrictions. The use of a “flywheel” diodes is recommended when an inductive load (relay) is being switched. 3-wire type proximity sensors Wiring sensor with mechanical contact 2-wire type proximity sensors 3-wire type proximity sensors General Inductive proximity sensors Electrical installation of electronic sensors Connection in series (continued) Connection in parallel
- 17. 31100 _Ver3.00-EN.fm/18 Schneider Electric 1 2 1 2 – R – C No limitation up to 200 m or up to a line capacitance of ≤ 0.1 µF (characteristics of sensor remain unaffected). It is, however, advisable to take into account voltage drop on the line. The proximity sensors are immune to electrical interference encountered in normal industrial conditions. Where extreme conditions of electrical “noise” could occur (large motors, spot welders, etc.), it is advisable to protect against transients in the normal way: - suppress interference at source, - limit the length of the cable, - separate power and control wiring from each other, - smooth the supply, - use twisted and screened cable pairs for output signals. In the event of machine or installation repairs (using an arc welder, for example), disconnect the proximity sensor. l The level of dust and damp protection depends on how carefully the screws, seals, cable glands, blanking plugs, etc. have been tightened. To ensure efficient dust and damp protection, use the correct diameter cable for the cable gland used. 2-wire type proximity sensors cannot be connected directly to an a.c. supply. This would result in immediate destruction of the proximity sensor and considerable danger to the user. An appropriate load (refer to the instruction sheet supplied with the sensor) must always be connected in series with the proximity sensor. At switch-on, it is necessary to limit (by resistor) the charging current of the capacitive load C. The voltage drop in the sensor can also be taken into account by subtracting it from the supply voltage for calculation of R. R = If the load comprises an incandescent lamp, the cold state resistance can be 10 times lower than the hot state resistance. This can cause very high current levels on switching. Fit a pre-heat resistance in parallel with the proximity sensor. R = x 10 U = supply voltage P = lamp power 1 Control cable 2 Power cable Cable gland Diameter of cable Ø min. Ø max. 7 mm plastic 3.5 6 9 mm plastic 6 8 11 mm plastic 8 10 13 mm plastic 10 12 U (supply) I max. (sensor) U2 P Wiring advice a.c. supply Capacitive load (C 0.1 µF) Load comprising an incandescent lamp General Inductive proximity sensors Electrical installation of electronic sensors Length of cable Separation of control and power circuit wiring Dust and damp protection of cable glands
- 18. 31100 _Ver3.00-EN.fm/19Schneider Electric Check that the proximity sensor is compatible with the supply being used. Check the load current characteristics : - if load current I ≥ nominal current, a relay should be interposed between the sensor and the load, - if I ≤ nominal current, check for wiring faults (short-circuit). In all cases, a “quick-blow” fuse should be fitted in series with the proximity sensor. Verify that the wiring conforms to the wiring shown on the proximity sensor label or instruction sheet Check that the proximity sensor is compatible with the supply ($ or ). Check that the supply voltage is within the voltage limits of the sensor. Remember that with rectified, smoothed supply : U peak = U rms x . Observe the wiring advice shown on page 31100/18. Refer to the instruction sheet supplied with the proximity sensor. For sensors with adjustable sensitivity, reduce the sensing distance. Check that the supply voltage is within the voltage limits of the sensor. Ensure that any d.c. supplies, when derived from rectified a.c., are correctly smoothed (C ≥ 400 µF). Separate a.c. power cables and d.c. low level cables. Where very long distances are involved, use suitable cable : screened and twisted pairs of the correct cross-sectional area. Position the sensors as far away as possible from any sources of interference. Check the suitability of the proximity sensor for the object to be detected. If necessary, select a proximity sensor with a higher switching frequency. Eliminate sources of radiated heat, or protect the proximity sensor casing with a heat shield. Problem Possible causes Remedy Output stage faulty or the short-circuit protection has tripped Wiring error Supply fault Eletromagnet interference Influence of surrounding metal Effect of interference on the supply lines Response time of the sensor too slow for the particular object being detected Influence of high temperature General Inductive proximity sensors Fast trouble shooting guide The sensor’s output will not change state when an object enters the operating zone False or erratic operation, with or without the presence of an object in the operating zone