Inductive Proximity Switch
Principle Of Operation
Inductive Proximity switch products high frequency altering field at the sensing face. When any metallic material enters in the sensing zone of the switch, the field gets disturbed. A Sensitive detector circuit senses this change which is further processed by amplifier circuit to produce output signal.
Fixing of the switches in the metal up to their sensing face.
Non Flush Mounting :
These switches are to be mounted keeping metal free zone around its sensing face.
Sensing Distance :
Sensing Distance of Inductive Proximity Switch depends on, Size of the Proximity Switch / Sensing Face and Material to be sensed.
|Switch Size||M8||M 12||M 18||M 24||M 30||M 36||M 48||M 70||Block|
|Sensing Distance Flush||1.5||2.5||4 – 5||6 – 8||10 – 12||13 – 15||12 – 15||20||–|
|Non Flush||–||3||6 – 8||8 – 10||11 – 15||17||15 – 20||30 – 35||15 – 17|
The sensing distance specified here is for object made of mild steel, having thickness of 1mm. Size of the object should be at least equal to the diameter of switch/ sensing face. For object other than M S apply suitable correction factor.
|1||Repeat Accuracy||0.02 mm|
|2||Hysteresis||3 – 10 %|
|3||Grade of Protection||IP67, for block type : IP55|
|4||Enclosure||Metallic (Nickel – Chrome plated brass) / Stainless steel / plastic|
|6||Ambient||60 0 C max|
|7||Switching Frequency||AC Switch||5 Hz|
|DC Switch||M 8 & M 12||5 KHz|
|Above M 18||1 KHz|
Three / Four Wire DC Switches Series : IS 3D/ 4D
These are three / four wire switches (+ ve, -ve and output) working on 10-30 v DC, and directly drives DC Relay. Theses switches are compatible with PLC modules because of its insignificant leakage current (50 μ A max) DC switches are divided into two categories according to load connection
- Load connected between supply wire and output wire : ( NPN )
- Load connected between ground wire and output wire : (PNP)
Entire range is available with NO or NC Logic. Special switches with change-over logic are also available. DC switches are protected against overload, short circuit and wrong polarity connection. Special switches with high operating frequency are available for applications of speed sensing. Special protection incorporated within the switch against back EMF from inductive load like relay.
Namur Sensor / Two Wire DC Proximity Switches Type : IS 2D
These are two wire current operated switches. The switch is designed for installation in hazardous areas. Switch draws current less than 3 to 4 mA in absence of metal and 1 mA in presence of metal. The switch is suitable for operation in hazardous area Group classification I, II A, II B, II C, as per IS 5780-1980 temperature class T4 (certified by CMRS Dhanbad), when fed through an intrinsically safe controller on zener barrier. This amplifier unit detects change in current and further processes to give output signal. Amplifier unit along with power supply and output relay fitted in separate enclosure with IP30 or IP55 grade of protection. These switches are compatible with internationally available intrinsically safe controller.
Two Wire AC Proximity Switches Type : IS 2A
AC Switches operated on 90 – 230 V AC and directly drive load like contactor or solenoid coil. Low voltage drop of 6 V across the switch makes it suitable to connect even two switches in series. Special protection against spurious signals is incorporated.
|Supply voltage||90 – 230 VAC|
|Load Current||150 – 200 mA suitable to drive siemens size ‘O’ connector or equivalent load. Special switches with load current of of 500 mA are also available in two wire version. Load current for Three Wire Proximity switch is 500 mA|
|Operated Frequency||5 Hz|
|Supply on Response|
|Delay||100 m sec|
|Max Surge Current||1 A Max (T < 20m sec / F, 1hz)|
|Noise immunity||AC proximity switches are protected against damage due to transient voltage peaks. Noise immunity for 4 KV / 20 micro sec|