Load cell is a sensor or a transducer that converts a load or force acting on it into an electronic signal.
This electronic signal can be a voltage change, current change or frequency change depending on the type of load cell and circuitry used.
Resistive load cells work on the principle of piezo-resistivity. This change in resistance leads to a change in output voltage when a input voltage is applied. Capacitive load cells work on the principle of change of capacitance which is the ability of a system to hold a certain amount of charge when a voltage is applied to it. For common parallel plate capacitors, the capacitance is directly proportional to the amount of overlap of the plates and the dielectric between the plates and inversely proportional to the gap between the plates.Nouveau gtx 1080 ti
A load cell is made by using an elastic member with very highly repeatable deflection pattern to which a number of strain gauges are attached. When the load is applied to the body of a resistive load cell as shown above, the elastic member, deflects as shown and creates a strain at those locations due to the stress applied.
As a result, two of the strain gauges are in compression, whereas the other two are in tension as shown in below animation.
This strain positive or negative is converted into an electrical signal by a strain gauge SG installed on the spring element. The simplest type of load cell is a bending beam with a strain gauge. Load Cell Working Animation. The four strain gauges are configured in a Wheatstone Bridge configuration with four separate resistors connected as shown in what is called a Wheatstone Bridge Network. An excitation voltage — usually 10V is applied to one set of corners and the voltage difference is measured between the other two corners.
At equilibrium with no applied load, the voltage output is zero or very close to zero when the four resistors are closely matched in value. That is why it is referred to as a balanced bridge circuit. When the metallic member to which the strain gauges are attached, is stressed by the application of a force, the resulting strain — leads to a change in resistance in one or more of the resistors. This change in resistance results in a change in output voltage.
This small change in output voltage usually about 20 mVolt of total change in response to full load can be measured and digitized after careful amplification of the small milli-volt level signals to a higher amplitude V or V signal. These load cells have been in use for many decades now, and can provide very accurate readings but require many tedious steps during the manufacturing process. There are various load cell designs in addition to bending beams.
This includes for example:. Dear sir i am very happy to see such a useful website and it is good tool for beginners. Hi Sir, Can u explain about the use of overall shield and individual sheild and where we have use IS and non IS cable sir. Save my name, email, and website in this browser for the next time I comment.
To summarize, we can say that if the angle between V1 and V2 is zero, the flow of active power becomes zero and the flow of reactive power depends on V1 — V2.
Thus for flow of reactive power there are two possibilities. The voltage-source converter is used to convert the DC input voltage to an AC output voltage.
Two of the common VSC types are as below. Transformer basically acts as a coupling medium.Up pcs mains physics paper
In addition, Tranformer neutralize harmonics contained in the square waves produced by VSC. Harmonic Filter attenuates the harmonics and other high frequency components due to the VSC. In case of reactive power demand increases in the power system, STATCOM increases its output voltage V1 while maintain the phase difference between V1 and V2 to zero it shall be noted here that there will always exists small phase angle between V1 and V2 to cater for the leakage impedance drop in the interconnecting Transformer.
Again, if the voltage of power system increase due to load throw off, STATCOM will reduce its output voltage V1 and therefore will absorb reactive power to stabilize the voltage to normal value. But as we know every equipment has got their own limitations, so STATCOM must also have some limitation of supplying or absorbing reactive power.Bluetooth beacon presence detection
Yes, there exists a limitation and this limitation is imposed by the current carrying capacity of force commutated devices like IGBT, GTO etc. Therefore, if the operation of STATCOM reaches their limitation, it does not further increases or decreases its output voltage V1 rather it supplies or absorbs fixed reactive power equal to its limiting value at a fixed voltage and current and acts like constant current source.
Voltage stability is one of the biggest problems in power systems. Engineers and researchers are trying to consolidate a definition regarding to voltage stability, besides proposing techniques and methodologies for their analysis. Concerning to voltage stability, such compensation has the purpose of injecting reactive power to maintain the voltage magnitude in the nodes close to the nominal values, besides, to reduce line currents and therefore the total system losses.
Today due the development in the power electronics devices, the voltage magnitude in some node of the system can be adjusted through sophisticated and versatile devices named FACTS.Fujiwara in fukuoka: im not going to end up a one-hit wonder
However, its active power capability can be increased if a suitable energy storage device is connected across the DC capacitor. Thank you so much for providing such a information which is very helpfuland easy way to understand. Your email address will not be published. Notify me when new comments are added. This site uses Akismet to reduce spam. Learn how your comment data is processed. Subscribe to our mailing list and get interesting stuff and updates to your email inbox.
The transformer consists of two separate windings placed over the laminated silicon steel core. The winding to which AC supply is connected is called primary winding and to which load is connected is called secondary winding as shown in the figure below.
It works on the alternating current only because an alternating flux is required for mutual induction between the two windings. Physically, there is no electrical connection between the two windings, but they are magnetically connected. Therefore, the electrical power is transferred from the primary circuit to the secondary circuit through mutual inductance.
Similarly induced emf in the secondary winding is proportional to the number of turns on the secondary side.
How Ethernet Works
As discussed above, the transformer works on AC supply, and it cannot work not DC supply. If the rated DC voltage is applied across the primary winding, a constant magnitude flux will set up in the core of the transformer and hence there will not be any self-induced emf generation, as for the linkage of flux with the secondary winding there must be an alternating flux required and not a constant flux.
The resistance of the primary winding is very low, and the primary current is high. So this current is much higher than the rated full load primary winding current. Hence, as a result, the amount of heat produced will be greater and therefore, eddy current loss I 2 R loss will be more. Because of this, the insulations of the primary windings will get burnt, and the transformer will get damaged.
It is defined as the ratio of primary to secondary turns. The transformation ratio is defined as the ratio of the secondary voltage to the primary voltage. It is denoted by K. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Circuit Globe All about Electrical and Electronics. Electronic Instrumentation. Very helpful… But need to short and to the point of the topic.TCP/IP and Subnet Masking
Wouldnt be anywhere in life without this article. Leave a Reply Cancel reply Your email address will not be published.The Optical Time Domain Reflectometer OTDR is an essential tool used to test the integrity of fiber optic cables, which can be applied to evaluate the length of fiber cables, measure transmission and connection attenuation and to detect the fault location of fiber links as well.
Based on these functions, it is commonly employed to fiber optical cable maintenance and construction. Moreover, OTDRs are most effective when testing long cables or cable plants with splices by illustrating where the cables are terminated and confirming the quality of the fibers, connections and splices.
Comparing with those sources and power meters which measure the loss of the fiber optic cable plant directly, the OTDR works indirectly. By duplicating the transmitter and receiver of the fiber optic transmission link, the source and meter make the measurement correlate well with actual system loss. However, the OTDR uses a unique optical phenomena "backscattered light" to make measurements along with reflected light from connectors or cleaved fiber ends, thus to measure loss indirectly.
During the process of OTDR testing, the instrument injects a higher power laser or fiber optic light source pulse into a fiber from one end of the fiber cable, with the OTDR port to receive the returning information. As the optical pulse is transmitted through the fiber, part of the scattered reflection will return to the OTDR.
Only useful information returned could be measured by the OTDR detector which acts as the time or curve segments of fibers at different positions. By recording the time for signals from transmission to returning and the speed of transmission in fibers, the distance thus can be calculated. The following picture shows exactly how an OTDR works for fiber optic testing.
Rayleigh scattering refers to the irregular scattering generated as optical signals transmitting in the fiber. This is because both transmission signal and backscatter loss are attenuated. Rayleigh scattering power is related to the wavelength of transmitted signal: the shorter the wavelength, the stronger the power, which means the backscatter lose generated by the trajectory of nm signal will be higher than that of nm signals.
In the higher wavelength region more than nmthe Rayleigh scattering will continue to decrease, and another phenomenon called infrared attenuation or absorption will appear to increase thus to cause an increase of the overall attenuation values.
Therefore, nm wavelength has the lowest attenuation, which testifies why it is a long distance communication wavelength. Similarly, OTDR of nm wavelength also has low attenuation, therefore it can be used for long distance testing as well. Fresnel reflection falls into the category of discrete reflection that is caused by the individual point of the whole fibers. These points are the result of changes in reverse coefficient elements such as glass and air gap. At these points, a strong backscatter light will be reflected back.
Therefore, OTDR uses the information of Fresnel reflection to locate the connection point, fiber optic terminal and breakpoints. Then, let's take a look at an important OTDR specification which originated from Fresnel reflections, known as "dead zones". Basically, there are two types of dead zones: event and attenuation. Both of them are expressed in distance that vary in accordance with the power of those reflections.
A dead zone refers to the length of time during which the detector is temporary blinded by a high amount of reflected light, until it recovers and can read light again. As the OTDR is working, time is converted into distance, therefore, more reflections lead to more time for the detector to recover, thus resulting a longer dead zone.Mobiscribe cover
Dead zone limits the operation of OTDR to a large extent, making it unable to locate and resolve faults. The following picture shows the dead zone of the OTDR. The dead zone seems like a problem when using OTDR for testing, however, adapting visual fault locator VFL can serve as an effective solution for solving this issue. It works as a complement to the OTDR in cable troubleshooting since it successfully covers the range where OTDRs fail to monitor because of the dead zone.
The visual fault locator is designed with a visible laser and universal adapter like FC, SC and ST etc, which contributes to locate faults on the fiber link easily.
For instance, to locating the breakpoint, bending or cracking of the fiber optic cables and locate the fault of ODTR dead zone as well. The higher power of a visual fault locator can find breaks in fibers or high losses around connectors in simplex cables.
If the light escapes at one break, it will be visible through the jacket of the fiber.Ethernet is a local area technology, with networks traditionally operating within a single building, connecting devices in close proximity. At most, Ethernet devices could have only a few hundred meters of cable between them, making it impractical to connect geographically dispersed locations. Modern advancements have increased these distances considerably, allowing Ethernet networks to span tens of kilometers.
In networking, the term protocol refers to a set of rules that govern communications. Protocols are to computers what language is to humans. Since this article is in English, to understand it you must be able to read English.
Ethernet Cables and How They Work
Similarly, for two devices on a network to successfully communicate, they must both understand the same protocols. What are the three types of VPN? What do you need to build a private WiFi network? What is a network server? Prev NEXT. Ethernet Basics. Protocols In networking, the term protocol refers to a set of rules that govern communications. Related What are the three types of VPN?Computer Networking : Principles, Protocols and Practice aka CNP3 is an ongoing effort to develop an open-source networking textbook that could be used for an in-depth undergraduate or graduate networking courses.
The first edition of the textbook used the top-down approach initially proposed by Jim Kurose and Keith Ross for their Computer Networks textbook published by Addison Wesley. CNP3 is distributed under a creative commons license. The second edition takes a different approach. The new features of the second edition are :.Symbol carriage return barcode
Numerous exercises are also provided as well as interactive quizzes that enable the students to verify their understanding of the different chapters and lab experiments with netkit and other software tools. The detailed bibliography encourages students to deepen their knowledge of the different topics by reading the hyperlinked references.
The book contains the following chapters :. The book can also be downloaded in pdf and epub format suitable for a tablet reader or ipad. It is also available on iTunes. A online bibliography that contains the bibtex references of the citations from the book is being developed on mendeley at.
The bibliography is being e expanded through the CNP3 blog that presents recent articles and documents that could be of interest to students who have studied networking by using the textbook. A set of slides with animations has been developed for CNP3. The slides were designed by using Apple's Keynote version The slides have been exported in powerpoint and pdf formats for non-Keynote users.
Two discussion groups have been created for students having questions about the content of the textbook. Like any open-source project, the future of Computer Networking Principles, Protocols and Practice will depend on its contributors. You can contribute to the project by :.
The source code of the entire code is managed by subversion. You can follow the update of the book on its dedicated facebook page. This work is licensed under a Creative Commons Attribution 3. Request new password. The new features of the second edition are : The second edition of the ebook is now divided in two main parts The first part of the ebook uses a bottom-up approach and focuses on the principles of the computer networks without entering into protocol and practical details.
It can be used as the first part of an undergraduate network course or as an introduction to computer networks for students who do not need to understand all the protocol details. This first part explains concepts such as the basic principles of the physical layerthe go-back-n and selective repeat mechanisms in the datalink layer, the key principles of the control and the data planes of the network layerthe principles of the transport layer and how resources are shared in a network The second part describes the operation of real protocols that use the principles explained in the first part.
Given that most IPv4 addressed have been allocated, more and more networks are moving to IPv6 and this ebook makes no exception. From a pedagogical viewpoint, the principles behind IPv6 and IPv4 are very similar and the ebook has chosen to only explain IPv6. Experience with the students shows that they easily understand the difference with IPv4. In the network layerboth the data and the control planes are described. Finally, in the datalink layerthe focus has been placed on Ethernet and WiFi Numerous exercises are also provided as well as interactive quizzes that enable the students to verify their understanding of the different chapters and lab experiments with netkit and other software tools.
The Application layer chapter explains the application layer and describes the operation of the Domain Name System, Internet email and the worldwide web The Transport layer chapter provides first a detailed explanation of the mechanisms that are used to provide a reliable transport service above an unreliable network service.
The Network layer chapter describes first the principles of the network layer, including link state routing and distance vector routing. Then, Ethernet and WiFi are explained in more details. A detailed Bibliography with links to relevant networking books, papers and RFCs. Slides A set of slides with animations has been developed for CNP3.
Introduction : Keynotepdfpowerpointslideshare Application layer : Keynotepdfpowerpointslideshare Transport layer : Keynotepdfpowerpointslideshare Network layer : Keynotepdfpowerpointslideshare Datalink layer and Local Area Networks : Keynotepdfpowerpointslideshare Discussion groups Two discussion groups have been created for students having questions about the content of the textbook.
How to contribute?On this radio-based network, several principles later used in the Ethernet were tested. One of the main ones involves sharing of a single medium by several stations using a time multiplex with random timing.
Whenever a station needed to send a packet, it would transmit it and wait for acknowledgement. If the packet was not acknowledged within a specified time perhaps due to a collision -- several stations trying to transmit at the same timeit was re-transmitted after a random delay.
Another main principle of Ethernet, carrier sensing, originated here. Before a station can transmit, it has to monitor the medium for a given period, and only begin transmission if no one else transmits. These beginnings gave Ethernet its relative reliability based on several robust properties. First, synchronization is transmitted at the beginning of each frame.
Ethernet utilizes a shared medium and serial communication. Communication occurs in frames. Each frame starts with a 6-byte destination address, followed by a 6-byte source address, actual data, and ends with a 4-byte CRC.
A synchronization sequence is transmitted before each frame; it consists of 31 pairs of '0' and '1' bits followed by two '1' bits that indicate the beginning of a frame.
These 64 bits are used for synchronization and automatic adjustment of receiver gains. Ethernet adapters insert them automatically when transmitting and strip them when receiving. Note: A receiver does not have to receive all 64 bits every time. Some of them may be lost if the transmitter does not turn on fast enough or if the receiver gain is not initialized properly.
Second, each data bit is transmitted together with a synchronization bit. This is implied by modulation -- Ethernet uses so-called Manchester II. This modulation scheme splits each bit interval into halves. The inverse of the data bit is transmitted in the first half, and its direct value in the second half.
It is possible to say that each bit coming to the transmitter is replaced by two bits, each occupies half of the original time slot. For example, the above synchronization sequence should look like this:. Clock signal on the first line synchronizes is input into the transmitter only.
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