Position sensors- inductive, capacitive, magnetic, laser, and photo sensors

In typical automation position detection switches are used for all types of applications. Some examples are position sensing, axis limits, motor speed detection, rotary positioning, part detection and more. Proximity switches come in many shapes, sizes, forms and types. This is a general over view showing the most common types of position sensors available and typical applications.

Types of Position detection sensors available

Inductive proximity switches detect metallic targets and are generally used for position sensing. Some sensors have the option for an optical setting aid.

Ideal for applications for position detection at high and low speeds applications. Typical maximum sensing range of around 80mm.

Good for position detection of non-metallic targets like plastic, glass, paper, wood etc.. Preferably do not use where coolant may heavily coat the switches. Capacitive is like the sensor pad on a laptop. If your finger is wet it will not sense properly.

Infrared and red light sensors are great for non contact sensing. Some of these sensors should also be avoided where sensors frequently are coated with coolant.

Typical configurations

1. Through beem
2. retroreflective
3. diffuse reflection
4. infrared heat sensors

Laser sensors are good for applications where small objects need to be detected or where very accurate positioning is required. The light beem is also visible for easy adjustment.

Typical configurations

1. Through beem
2. retroreflective
3. diffuse reflection

Fiber optic controllers and sensors provide reliable detection of small targets and can be used to control multiple applications.

Typical configurations

1. Light on
2. Dark on

Analog type position detection gives accurate linear postion and comes in almost infinite lengths based on the application




Position sensor specification and considerations

Standard switches

1. 12vdc
2. 24vdc
3. 100vac
4. 115vac

Analog switches- Voltage range required

1. 0-10vdc
2. -5 to +5 vdc
3. -10 to +10vdc
4. 4-20mA
5. 0-20mA

1. Is it PNP?
   2-wire-Positive voltage in Positive out to machine PLC as an input
   3-wire-Positive and negative in from power supply Positive out to machine input

2. Is it NPN?
   2-wire-Positive voltage in Positive out to a Machine PLC as an Input
   3-wire-Negative and positive in from power supply Negative is output to machine input
   
   

Typical diameters (most common)- 8 mm, 12 mm, 18 mm, and 30 mm

Sensing distance required

Sensing distances (most common)-3 mm, 4 mm, 5 mm, 8 mm, 12 mm, 18 mm, and 30 mm

Material construction

1. Metal
2. Plastic

1. Oils and coolants
2. magnetic fields
3. Hygienic and wet areas
4. Mobile applications
5. Food applications
6. Caustic and acid solutions
7. Shock resistance
8. Electrical noise
9. Dust or debur type applications