Different Types of Switches and Sensors Used in Automation
1. Toggle Switches
2. Pushbuttons
3. Limit Switches
4. Selector Switches
5. Proximity Sensors
6. IR Sensors
7. Photosensors
8. Level Switches
9. Pressure Sensors
10. Temperature Sensors
1. Toggle switches are actuated by a lever angled in one of two or more positions. The common light switch used in household wiring is an example of a toggle switch. Most toggle switches will come to rest in any of their lever positions, while others have an internal spring mechanism returning the lever to a certain normal position, allowing for what is called "momentary" operation.
2. A switch that is open when un-actuated is called normally-open. A switch that is closed when un-actuated is called normally-closed. Sometimes the terms "normally-open" and "normally-closed" are abbreviated N.O. and N.C., respectively.
3. Some switches are specifically designed to be operated by the motion of a machine rather than by the hand of a human operator. These motion-operated switches are commonly called limit switches.
4. Selector switches are actuated with a rotary knob or lever of some sort to select one of two or more positions. Like the toggle switch, selector switches can either rest in any of their positions or contain spring-return mechanisms for momentary operation.
5. Proximity switches sense the approach of a metallic machine part either by a magnetic or high-frequency electromagnetic field. Simple proximity switches use a permanent magnet to actuate a sealed switch mechanism whenever the machine part gets close (typically 1 inch or less).
6 & 7. These sensors are designed for applications involving Non-contact detection for measuring , counting and positioning.These switches offer sensing range upto 5M. Emitter and Receiver are in separate housings facing each other with their optical axes matched. Sensor switches whenever light beam is interrupted. App: Monitoring doors and gates.
8. A floating object can be used to actuate a switch mechanism when the liquid level in an tank rises past a certain point.
9. Pressure transducer converts pressure into an analog electrical signal, which is achieved by the physical deformation of strain gages which are bonded into the diaphragm of the pressure transducer and wired into a Wheatstone bridge configuration. Pressure applied to the pressure transducer produces a deflection of the diaphragm which introduces strain to the gages. The strain will produce an electrical resistance change proportional to the pressure. One of the most common is the strain-gage base transducer.
2. Pushbuttons
3. Limit Switches
4. Selector Switches
5. Proximity Sensors
6. IR Sensors
7. Photosensors
8. Level Switches
9. Pressure Sensors
10. Temperature Sensors
1. Toggle switches are actuated by a lever angled in one of two or more positions. The common light switch used in household wiring is an example of a toggle switch. Most toggle switches will come to rest in any of their lever positions, while others have an internal spring mechanism returning the lever to a certain normal position, allowing for what is called "momentary" operation.
2. A switch that is open when un-actuated is called normally-open. A switch that is closed when un-actuated is called normally-closed. Sometimes the terms "normally-open" and "normally-closed" are abbreviated N.O. and N.C., respectively.
3. Some switches are specifically designed to be operated by the motion of a machine rather than by the hand of a human operator. These motion-operated switches are commonly called limit switches.
4. Selector switches are actuated with a rotary knob or lever of some sort to select one of two or more positions. Like the toggle switch, selector switches can either rest in any of their positions or contain spring-return mechanisms for momentary operation.
5. Proximity switches sense the approach of a metallic machine part either by a magnetic or high-frequency electromagnetic field. Simple proximity switches use a permanent magnet to actuate a sealed switch mechanism whenever the machine part gets close (typically 1 inch or less).
6 & 7. These sensors are designed for applications involving Non-contact detection for measuring , counting and positioning.These switches offer sensing range upto 5M. Emitter and Receiver are in separate housings facing each other with their optical axes matched. Sensor switches whenever light beam is interrupted. App: Monitoring doors and gates.
8. A floating object can be used to actuate a switch mechanism when the liquid level in an tank rises past a certain point.
9. Pressure transducer converts pressure into an analog electrical signal, which is achieved by the physical deformation of strain gages which are bonded into the diaphragm of the pressure transducer and wired into a Wheatstone bridge configuration. Pressure applied to the pressure transducer produces a deflection of the diaphragm which introduces strain to the gages. The strain will produce an electrical resistance change proportional to the pressure. One of the most common is the strain-gage base transducer.
Pressure transducers are generally available with three
types of electrical output
Ø Millivolt
Ø Volt and
Ø 4-20mA
10. Thermocouples are sensors for measuring
temperature. They consists of two dissimilar metals
wires, joined together at
one end. When this junction of the two metals is heated or cooled a voltage
is
produced that can be correlated back to the temperature.
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