VACUUM CIRCUIT BREAKERS
Circuit breakers are devices which can automatically break a circuit under fault conditions and it can make the circuit manually after the fault. Circuit breakers are classified into different types. One of the main circuit breaker among them is Vacuum circuit breaker. Here vacuum is used to extinct the arc. Arc extinction is the main process of a circuit breaker
Before that, it is needy to explain how an arc is produced. Circuit breaker has two contacts- Fixed and movable, otherwise called as electrodes. Normally the contacts remain closed but if any fault occurs these contacts open automatically and of course can be opened manually.
We know that circuit breakers work under the instructions from relay. When the trip coils from relay energize, circuit breaker identifies fault occurred and hence the contacts are pulled apart. A high intensity current flows through the contacts of the circuit breaker before they are opened by the system. At the same instant contacts begin to separate and causes heavy heat and temperature in between the contacts. This is termed as an arc. This heat is highly dangerous and can cause heavy damage to the whole system. So it has to be extinguished in no time.
Vacuum is having superior qualities over other arc quenching medium. It has high insulating strength. When the contacts are opened in vacuum, the arc is produced in between them. It got extinguishes quickly since the metallic vapours and ions produced during the arc rapidly condense on the surface of the circuit breaker contacts, resulting in quick recovery of dielectric strength.
The contacts of Vacuum circuit breaker and arc shied is mounted inside a vacuum chamber. The chamber is connected to the control mechanism by means of stainless steel bellows. A glass vessel is used as the outer insulating body. This is all about its construction.
Vacuum circuit breaker is really the most reliable one with low cost, no fire hazards, no gas generation, low arc energy, little maintenance and low inertia.
Thursday, November 12, 2009
Sunday, November 8, 2009
What is an Actuator?
Actuator is a typical mechanical device used to move or control a mechanism or a system. This device gains energy for its working from air, electricity or liquid and then converts it into some kind of motion.
In engineering field actuators have many more applications in different sectors. In this field actuators are used as mechanisms to provide motion and are again used to stop the motion of that particular device. So it is clear that actuator just actuates the motion. May be start or stop, depends on the machine.
In electronics engineering, actuators are subdivisions of transducers. They are used to transform input signal into motion. Normally input signal would be electrical. E.g. electrical motors, pistons, relays, pneumatic actuators, piezo electric actuators etc. Actuators can be sometimes used as hardware components. Different types of actuators are available like plasma actuators, pneumatic actuators, electric actuators, linear actuators.
It’s a type of tool used to put something into automatic action. Actually actuators are used with number of sources. Depending on the type of actuator we are using, different tools will be assisting us to put the device to motion. Mostly they are used in office work area since most of them are used to move valve door in systems.
Sometimes they are used to maneuver certain mechanical devices on work. Depending on the shape and style actuators are divided into different classes. Linear actuators, valve actuators, hydraulic actuators are the best known and used among them. Each of them has assigned functions e.g. hydraulic actuators are used to allow more pressure, size and movement with the object.
All of these different types of actuators are best when knowing what type of motion control you need. They also provide speed, Belt drive, acceleration and accuracy with linear motion No matter what type of actuator is needed, there is a tool that makes it easier to maneuver a certain object or space in your work area.
In engineering field actuators have many more applications in different sectors. In this field actuators are used as mechanisms to provide motion and are again used to stop the motion of that particular device. So it is clear that actuator just actuates the motion. May be start or stop, depends on the machine.
In electronics engineering, actuators are subdivisions of transducers. They are used to transform input signal into motion. Normally input signal would be electrical. E.g. electrical motors, pistons, relays, pneumatic actuators, piezo electric actuators etc. Actuators can be sometimes used as hardware components. Different types of actuators are available like plasma actuators, pneumatic actuators, electric actuators, linear actuators.
It’s a type of tool used to put something into automatic action. Actually actuators are used with number of sources. Depending on the type of actuator we are using, different tools will be assisting us to put the device to motion. Mostly they are used in office work area since most of them are used to move valve door in systems.
Sometimes they are used to maneuver certain mechanical devices on work. Depending on the shape and style actuators are divided into different classes. Linear actuators, valve actuators, hydraulic actuators are the best known and used among them. Each of them has assigned functions e.g. hydraulic actuators are used to allow more pressure, size and movement with the object.
All of these different types of actuators are best when knowing what type of motion control you need. They also provide speed, Belt drive, acceleration and accuracy with linear motion No matter what type of actuator is needed, there is a tool that makes it easier to maneuver a certain object or space in your work area.
Wednesday, November 4, 2009
DIGITAL SIGNAL PROCESSING (DSP)
What is Digital Signal Processing?
It’s a major branch of science that deals with the representation of signals as symbols or sequences and after that these signals are getting processed. There are two subfields of processing available- Analog signal processing and Digital signal processing.
This digital signal processing also includes subfields like audio and speech processing, sonar and radar processing, sensor array processing, spectral estimation, statistical signal processing, digital image processing, signal processing for communication systems, biomedical signal processing, seismic signal processing etc. So from the above description it’s clear that DSP is a vast branch in engineering field that requires genuine attention and development.
Generally these processing measures the continuous analog signals and is then converted into digital form by means of an Analog to Digital converter (A-D converter). For certain, the required output would be in Analog form, so the signal is then converted to Analog using Digital to Analog converter (D-A converter). We know that this process is very complex when compared with analog processing and hence error detection and correction methods are used to clarify the process.
The main notable advantage of DSP is that it is less affected to noise and hence non vulnerable. DSP algorithms are carried out in special processors like Digital Signal Processors which is inbuilt in the systems. Since the process is very lengthy and time consuming, we usually undergo the process in this type of processors. DSP’s include microprocessors, digital signal controllers, field programmable gate arrays etc. DSP’s can be implemented using specialized microprocessors like DSP56000, TMS320 and the SHARC.
Usually the digital signals are denoted in time domain, frequency domain, spatial domain etc. With the available characteristics, it is decided that on which domain the signal can be denoted. Sampling is another important point to be specified. Sampling can be done in signal processing during two stages discretization and quantization. In the dicretization stage the space of signals are divided into equivalence classes and quantization is carried out by replacing the signals with representative signals.
DSP has applications in the fields of audio signal processing, audio compression and in the fields as mentioned earlier.
It’s a major branch of science that deals with the representation of signals as symbols or sequences and after that these signals are getting processed. There are two subfields of processing available- Analog signal processing and Digital signal processing.
This digital signal processing also includes subfields like audio and speech processing, sonar and radar processing, sensor array processing, spectral estimation, statistical signal processing, digital image processing, signal processing for communication systems, biomedical signal processing, seismic signal processing etc. So from the above description it’s clear that DSP is a vast branch in engineering field that requires genuine attention and development.
Generally these processing measures the continuous analog signals and is then converted into digital form by means of an Analog to Digital converter (A-D converter). For certain, the required output would be in Analog form, so the signal is then converted to Analog using Digital to Analog converter (D-A converter). We know that this process is very complex when compared with analog processing and hence error detection and correction methods are used to clarify the process.
The main notable advantage of DSP is that it is less affected to noise and hence non vulnerable. DSP algorithms are carried out in special processors like Digital Signal Processors which is inbuilt in the systems. Since the process is very lengthy and time consuming, we usually undergo the process in this type of processors. DSP’s include microprocessors, digital signal controllers, field programmable gate arrays etc. DSP’s can be implemented using specialized microprocessors like DSP56000, TMS320 and the SHARC.
Usually the digital signals are denoted in time domain, frequency domain, spatial domain etc. With the available characteristics, it is decided that on which domain the signal can be denoted. Sampling is another important point to be specified. Sampling can be done in signal processing during two stages discretization and quantization. In the dicretization stage the space of signals are divided into equivalence classes and quantization is carried out by replacing the signals with representative signals.
DSP has applications in the fields of audio signal processing, audio compression and in the fields as mentioned earlier.
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