Tuesday, 28 October 2014

Push Button

What is Push-button?

Push button is a component which connects two points in a circuit when we press it. In industry it can be used to provide input to circuit.

Push Buttons
Circuit Diagram
In the daigram shown below point A & B are connected when switch is pressed.


Application
The "push-button" has been utilized in calculators, push-button telephones, kitchen appliances, and various other mechanical and electronic devices, home and commercial.
In industrial and commercial applications, push buttons can be connected together by a mechanical linkage so that the act of pushing one button causes the other button to be released. In this way, a stop button can "force" a start button to be released. This method of linkage is used in simple manual operations in which the machine or process have no electrical circuits for control.







Thursday, 16 October 2014

Photoelectric Sensor

  1. Photoelectric sensor, or photo eye, is a device used to detect the distance, absence, or presence of an object by using a light transmitter, often infrared, and a photoelectric receiver. They are used extensively in industrial manufacturing. There are three different functional types: opposed (through beam), retro-reflective, and proximity-sensing (diffused).

  2. Photo electric sensor
    Application
  3. Photoelectric sensors use a beam of light to detect the presence or absence of an object. This technology is an ideal alternative to inductive proximity sensors when you require long sensing distances or when the item you want to sense is non-metal. Our photoelectric sensors satisfy applications found in many industries, such as material handling, packaging, food processing, and transportation. For your specialized applications that require a non-standard connector or cable, we can customize the sensor connections.
  4. Modes
  5. In (through beam) arrangement consists of a receiver located within the line-of-sight of the transmitter. In this mode, an object is detected when the light beam is blocked from getting to the receiver from the transmitter.
  6. A retro-reflective arrangement places the transmitter and receiver at the same location and uses a reflector to bounce the light beam back from the transmitter to the receiver. An object is sensed when the beam is interrupted and fails to reach the receiver.
  7. A proximity-sensing (diffused) arrangement is one in which the transmitted radiation must reflect off the object in order to reach the receiver. In this mode, an object is detected when the receiver sees the transmitted source rather than when it fails to see it.
  8. Modes of Photoelectric sensors
    Photoelectric sensors offer many advantages as compared to other technologies such as inductive,capacitive,magnetic & ultrasonic.They are price competitive as well when compared to other technologies.
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Saturday, 11 October 2014

Solenoid Valve


A solenoid valve is an electromagnetically operated valve.It is controlled by an electric current through a solenoid: in the case of a two-port valve the flow is switched on or off; in the case of a three-port valve, the outflow is switched between the two outlet ports. Multiple solenoid valves can be placed together on a manifold.
Solenoid valves are the most frequently used control elements in fluidics. Their tasks are to shut off, release, dose, distribute or mix fluids. They are found in many application areas. Solenoids offer fast and safe switching, high reliability, long service life, good medium compatibility of the materials used, low control power and compact design.

Solenoid Valve


Operation


There are many valve design variations. Ordinary valves can have many ports and fluid paths. A 2-way valve, for example, has 2 ports; if the valve is open, then the two ports are connected and fluid may flow between the ports; if the valve is closed, then ports are isolated. If the valve is open when the solenoid is not energized, then the valve is termed as normally open (N.O.). Similarly, if the valve is closed when the solenoid is not energized, then the valve is termed normally closed.

Operation of Valve


Common uses

Solenoid valves are used in fluid power pneumatic and hydraulic systems, to control cylinders, fluid power motors or larger industrial valves. Automatic irrigation sprinkler systems also use solenoid valves with an automatic controller. Domestic washing machines and dishwashers use solenoid valves to control water entry into the machine. Solenoid valves are used in dentist chairs to control air and water flow. In the paintball industry, solenoid valves are usually referred to simply as "solenoids." They are commonly used to control a larger valve used to control the propellant (usually compressed air or CO2). In addition to this, these valves are now being used in household water purifiers (RO systems).
Besides controlling the flow of air and fluids, solenoids are used in pharmacology experiments, especially for patch-clamp, which can control the application of agonist or antagonist.

Friday, 10 October 2014

Rotary Encoder

What is Rotary Encoder


It is an electro-mechanical device that coverts the angular motion/position of the shaft to analog or digital code.It is also known as shaft encoder.

Application
Rotary encoders can be used in all applications that require monitoring rotation rate, speed, acceleration and direction. These sensors can be utilized in many applications found in mechanical engineering, the conveyor industry, material handling and the packaging industry. You are certain to find a suitable rotary encoder for your application from our broad product offering.
In automation, rotary encoders are used as sensors for angle, position, speed and acceleration. Linear motion can also be measured through the use of spindles, gear racks, measuring wheels or cable pulls.
Rotary encoders convert a mechanical input into electrical signals, which can be processed by counters, tachometers, programmable logic controllers and industrial PCs.

Rotary encoders in many application which require precise shaft unlimited rotation specialy in robotics,industrial control,special purpose photographic lense,computer input devices(mouse & trackballs)


Absolute rotary encoder ROQ 425
There are two types of rotary encoder :

  • Absolute
  • Incremental(Relative)
A Gray code absolute rotary encoder with 13 tracks. At the top the housing, interrupter disk, and light source can be seen; at the bottom the sensing element and support components.
                                                               
Absolute Encoder

Output of absolute encoder indicates current position of the shaft.It maintains position information when power is removed from the system and when power is again to the system the position is retrieved.

Incremental Encoder

Output of incremental encoder supplies information regarding motion of the shaft in terms of speed,distance,position.It doesn't power up with fixed relation between encoder state and position.

Use in industry

Encoders used on servomotors

Rotary encoders are often used to track the position of the motor shaft on permanent magnet brushless motors, which are commonly used on CNC machines, robots, and other industrial equipment. Incremental (Quadrature) encoders are used on Induction Motor type servomotors, but absolute encoders are used in Permanent Magnet Brushless Motors, where applicable. In these applications, the feedback device (encoder) plays a vital role in ensuring that the equipment operates properly. The encoder synchronizes the relative rotor magnet and stator winding positions to the current provided by the drive. Maximum torque results if the current is applied to the windings when the rotor magnets are in a particular position range relative to the stator windings. The motor will perform poorly or not at all if this timing is not adjusted correctly. Improper encoder alignment on the motor can actually cause it to run backwards sometimes resulting in a hazardous run away condition. Correct alignment is essential to proper operation of these motors.

Thursday, 9 October 2014

Relay

What is RELAY?

Relay can be defined as electrically operated switch.They mostly use electromagnet to operate a switch.They are used to control a circuit by low power signal or where several circuits must be controlled by one signal.During initial phase relays were extensively used in telephone exchanges and early computers to perform logical operations.



As shown in figure above a simple electromagnetic relay consists of a coil wrapped upon a soft iron core,a iron yoke that provides low reluctance path for magnetic flux,movable armature made up of ferromagnetic material and one or more sets of contacts.The armature is hinged to yoke and is mechanically linked with contacts.Armature is held by spring such that when relay is d energized,there is an air gap in magnetic circuit.In this case one set of contacts is opened where as other set is closed.




Working

When electric current passes through the coil a magnetic field is generated which activates armature and consequent movement of movable contacts with fixed contacts(makes/breaks).

In industry Normally Open/Closed (NO/NC) term is used to define working of relay.

Wednesday, 8 October 2014

Pneumatics



Pneumatics deals with application & study of pressurised gas in order to produce mechanical motion.Pneumatic system used in various factories & industries  these days use compressed air / compressed inert gas.This is because a centrally located and electrically powered compressor,that powers cylinders and other pneumatic devices through solenoid valves can often provide motive power in a cheaper,safer,more flexible, and more reliable way than a large number of electric motors and actuators.


Electric Slide(FESTO)
Most industrial pneumatic applications use pressures of about 80 to 100 pounds per square inch (550 to 690 kPa).

In the figure above as an example of pneumatic system a Electric Slide is shown ,which can be used in various industries where fast movement is required for example for cutting piece of cloth in textile industry(cutter attached to electric slide) in a automated way controlled by PLC and various other applications can be found as well.

Moisture removed air is used in Pneumatic system.


EXAMPLES: Air brakes on bus/truck/train,air compressor ,air engines,HVAC control system,pressure regulator,pressure sensor,vacuum pump etc


Advantages of Pneumatic System

Simple Design,long operating live,little maintenance required,low chance of fire as compared to hydraulic oil.