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I have manual but unable to get answer of some Childish Question
like how to extract signal from GTAO
How to connect various component.
Interfacing of RTDS to Relay
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التكرار والتصحيح والاعادة هي الطريق الاسلم والافضل للتعلم
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- Breaker interlock scheme
- Under-frequency relay (81) scheme
- Programmable logic controller-based load shedding
- Fast intelligent load shedding (ILS)
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According to me, micro processor based load shedding control are more easy and reliable to use, could refer my papers.......
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The above model is useful in studying and testing the distance relay when a fault occurs at 75% of the length of the line because the line is divided into four equal parts.
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Dear Bashar
So I am, I agree with Pablo Gómez
Best regards
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Cooperative communication (CC) can be explored to counter eavesdropping. Relaying and jamming are the sub techniques of (CC). However, Jamming is used to counter the strong eavesdroppers. Is there any other technique except Jamming to counter strong eavesdroppers in the network?
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You can use cryptography with more than 512-bits keys, and special signals on a physical level, such as Nonorthogonal FDM (N-OFDM) with the coding of frequency positions:
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Our answer is a consistent YES. A qubit (or quantum bit) is today the quantum mechanical analogue of a classical bit. In classical computing the information is supposed to be encoded in bits, where each bit can have the value zero or one. In quantum computing the information is, then, also encoded in qubits.
This is inconsistent in (1), in a most basic point, because even classically, information is no longer understood to be encoded in bits. Years ago, this was true 50 years ago, but failed.
Today, one uses SystemVerilog with tri-state chips, as opposed to Shannon's theory with binary states, and two-state chips as relays.
Information is encoded in three logical states, in 0, 1,and Z, where Z is an open circuit standing for indeterminacy, with a coherent semantics for interconnects.
The qubit view is inconsistent in (2), another basic way, because one needs to move from the macroscopic, from a classical Boolean analogy of relays or switches, valid for the Law of the Excluded Middle (LEM). Then, in a formless and classical “fluid” model for particles, information was seen in the double-slit experiment as GF(2^m), and now must change to a more complex microscopic structure, with a quantum tri-state+, not qubit in two-state. The photon (e.g., a particle) is now modeled by an algebraic approach with ternary object symmetry, modeled by GF(3^n).
Comparatively, the current two-state quantum theory of qubits is linked, however, to the classical two-state “bit”, following Boolean or classical logic laws, such as the LEM, which carry only two possible values, “0” and “1”. This emulates the workings of a relay circuit, and uses the formless “fluid” analogy of classical information, that can only be blocked (relay open), routed or replicated (relay closed). However, information can also be encoded, in analogy to network encoding as announced in 2000, and not covered by Shannon's theory.
What is your qualified opinion?
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Max Planck solved the ultraviolet catastrophy by his study of black body radiation where he found the energy of oscillating system is quantized, not continuous as the classical physics thought before 1900.
So, radiation is made of quanta with energy depending on the frequency f i.e E = hf, where h is proportionality constant. Einstein, in 1917, proved it by reproducing the law of radiation found in 1900 by Max Planck. That required a coherent channel to exist, invalidating qubits before their concept started. It was a mistake by Shannon that led to bits and qubits.
The mistake was first that Information could be treated as a fluid, which can only be blocked or let pass, as a relay. That led Shannon to consider Boolean logic for Information, the second mistake. Which led to qubits, the third mistake in treating Information. One must use tri-state+ to represent Information, classically or quantically.
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In case, HRC fuse of motor protection in downstream takes more time to blow than the pick up time of Earth Fault relay, the incomer trips & interrupts whole plant auxiliry.
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IDMT selection time, should be higher than HRC fuses ….
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Normally, for a forward fault, phase difference between voltage and current of relay (theta) lies between -90 and +90; and for a reverse fault, theta is outside of this range. Some works, however, use negative components of voltage and current of relay to identify fault direction. I want to know that what is the criterion for a forward/reverse fault in this condition? In my simulation studies, phase difference between negative components of voltage and current lies between -90 and +90 for a reverse fault.
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The negative- and zero-sequence networks are passive, no "source" behind the relay. The fault (unbalance, in general) acts as a source that excites the V2 and I2 quantities at the relay location. So for a forward fault (the Thevenin source in front of the relay), V2 = -I2*Z2SYS_LOC, and for a reverse fault (the Thevenin source behind the relay) V2 = +I2*(Z2LINE+Z2SYS_REM). Similarly for the zero-sequence and incremental-quantity directional elements. More details in this primer (paper and presentation): Sequence Component Applications in Protective Relays - Advantages, Limitations, and Solutions
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We know that the eavesdroppers are malicious nodes and they are not supposed to cooperate with the users. If we exploit opportunistic relaying protocol for the destination, can we consider the same protocol for the eavesdropper? If so, then how the CSI of the eavesdropper can be estimated at the relay?
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I apologize for not knowing
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Let us consider that we want to use a relay with an energy harvesting scheme. It has only a single antenna. Can the relay receive both information and energy signals through that single antenna? Consider that the information and energy signals are transmitted at different time slots.
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I think you don't need different time slots. If you would apply frequency modulation, for example, you had both constant energy flow and uninterrupted information flow.
As an practical example, I remember the case of the owner of a garden near a broadcasting antenna in Berlin, about 60 years ago, who lightened his garden shed by some low voltage bulbs connected a piece of wire. Unfortunately, instead of honoring his ingenuity, the authorities stopped him. :-)
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Consider a dual-hop system where a single source tries to send any information to a group of multicast receivers in the presence of multiple eavesdroppers. Also, assume that there is no direct link between the source and the receivers. So, to transmit the data, the best relay selection scheme is utilized to choose among multiple relays.
In this case, is the perfect channel state information (CSI) of both receivers and eavesdroppers necessary for applying the best relay selection scheme?
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Dear @
Same for you!
I have a question that may help us to answer your question.
Why do you want to know the channel sate information for an eaves dropper?
Only in the case that you want to nullify its recieved signal or make it less than his receiver sensitivity, you have to know its channel sate information.
Then the problem will be similar to that of the space multiplexing MIMO.
What I mean it depends on how do you want to prevent the eaves
dropping.
Best wishes
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I have characteristic in another simulation but i need it in matlab to build my system to modify it easily
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You can see my papers there I done matlab coding for Graphs. I think you can find your answer.
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We have this controller in our 1200 C furnace :PEW-202/PEW-205:
We need a programmable controller and relay.
What would you suggest?
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Hope you are well!
In order to find an equivalent controller you need to list the specifications given in the manual of the temperature controller: PEW-202/PEW-205.
You need also to give the specifications of the relay as they are written on it.
or to give its type as you made by the controller.
Knowing the specifications one can easily find a suitable match to your instruments.
As a solution you can use a National DAQ card and laptop as a controller.
Best wishes
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Cooperative relays have been studied to enhance the physical layer security. Node selection and artificial noise generation are used to degrade the performance of eavesdroppers. Recently, intelligent reflective surface(IRS) has also been introduced to improve the PLS. Therefore, Which one is better?
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I don't think one can give a definitive answer to broad questions like this. You are mentioning two general ways of increasing PLS. The first one is to transmit the signal in a directive manner towards the receiver, in hope that the eavesdroppers will not achieve any directivity gain. An IRS can be used to achieve towards this end. The second one is to transmit artificial noise in other directions. I don't think that an IRS is useful for that.
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It is well known that fast fault clearance is of vital importance for the High Voltage Power Systems, but unfortunately in Distance Relay protection, the faults on the protected HVTL near the remote end substation postpone to the 2nd zone which includes time delayed.
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Because of the errors in impedance measurements, (CT and VT), because of errors in HV transmission lines parameters (R. L. G. C), so the 100% zone can cover busbars in second (end) substation and cause the distance protection to act and false switch of the line, (but the fault is at the busbar at the second substation!
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For example, let's assume a fault external to the microgrid in which the voltage and frequency levels are outside the ride through range. Which protection should act first: 27, 67 or 81? Could a directional overcurrent relay act faster than a frequency relay in these conditions?
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Dear Cleberton Reiz, in this case, why do you need to establish priorities for these protections functions? All of them will have the same effect, i.e. islanding the microgrid, right? As I see, if your microgrid is outside the fault ride through region for the required amount of time, it is entitled to go into island mode. It does not matter what protection function wins the race to trip the breaker first. Am I missing something?
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and also when a DLBCL patient should be tested for the ALK ? currently, i relay on the morphology, is that enough?
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Thank you,Dr Muhammad Ali
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Hello,
I'm working on a PFC Totem pole for an On Board Charger application.
I would like to know how to manage the soft start procedure to slowly charge the DC link capacitor and so limit the inrush current.
I know that a PTC (or NTC) thermistor can be used with a relay. I also read that the DC voltage reference (the ref of the outer voltage loop) can be slowly incremented (a ramp).
It's really confuse :
  • When should I open and then close the relay to short the thermistor (time? DC voltage reach a defined level? loop are in steady state? ...)
  • What about the DC voltage reference? When should I start to increment it? from 0 to 400V?
  • What about the state of MOSFETs during soft start procedure?
  • How to simulate in Simulink the system Thermistor+Relay
Thanks a lot for your precious answers !
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Dear Alexis,
The thermistor is a negative temperature coefficient semicondcutor resistor. It can be used to limit the current during the staring process as its value starts large and due to its selfheating it will be decreased and the current passing in in it increases. In this way the current rises slowly with time and the start will be soft.
So in order to charge the capacitor relatively slowly one has to connect a series resistance with it. Since one needs only that the resistance will be effective only during the charging phase then one uses thermistor.
So to switch it out after the current reached value one connect parallel to it a RELAY and control it with the current passing through the resistor. That is the control circuit of the relay is operated with a current comparing circuit.
Best wishes
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Suppose there is a mobile device at the edge of a cell of a 5G wireless network which has a weak channel with the base station. The edge user can utilize relay assisted D2D communications proposed for 5G. Assume the edge user broadcast a call and expect it to reach at least one neighboring relay. How can the reliability of the broadcast call reaching at least one neighboring relay be mathematically modeled for 5G by taking 3GPP standards into consideration?
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Could you check my papers, reply to your question Vishaka Basnayake
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I need help in understanding the mechanism to measure/estimate health of DC contactors and DC relays used in industrial grade power systems. What are the mechanisms and tools used for this purpose ?
Please share links for the material or the material itself.
Thanking in advance.
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Hello Ahmad Usman ,
Sorry, I forgot to mention some of the instrumentation you will need. For contact resistance measurements, you will need a milli-ohm meter with Kelvin leads (4-wire measurement with one pair for drive current and one pair for voltage sensing), and a small, portable microscope to visually check the contacts for pitting and material transfer. The resistance of the coils can probably be measured with a normal ohm meter. And the closing and opening times can be measured with an oscilloscope and some fixturing to provide test signals.
Regards,
Tom Cuff
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How can we mathematically model the reliability of a multicast or broadcast data reaching a neighboring relay?
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Hello Vishaka Basnayake , thanks. On researchgate we tend to click "recommend" on the answer of use, it helps people see what helps and what helps less.
Keep me posted on your investigation... You have an interesting question indeed
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I am simulating a Mechanical DC circuit breaker. I used a step to put on and off. I wanted to use a "compare to constant" block so that when the fault current goes over the threshold the ideal switch can trip. The step is connected to the ideal switch so I cannot connect a relay too. Any help will be much appreciated.
Thanks
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Simply include a SWITCH block from Commonly used blocks of Simulink and connect its output terminal to the gate(g) terminal of breaker. Compare the current threshold value and feed the logical output which decide the switching conditions to the control input of SWITCH(2nd terminal). Add a constant zero to 1st input of the SWITCH, which will refer as the switching off criteria during fault exceeding threshold, whereas the 3rd terminal will be fed with the earlier Step signal.
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Several pieces of research model this self-interference (SI) using different random distributions like Rician, Nakagami-m, Rayleigh, etc. The cancellation techniques allow the SI suppression up to a certain level and only a very small amount of residual SI remains. According to my understanding, due to the presence of transmitting and receiving antennas at the same node the LOS component will dominate that can be canceled using cancellation techniques. But due to multipath effects, the residual SI component is very small.
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Nakagami-m is generalized, however, recently Rice university researchers proposed through experiments the Rice distribution.
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I have been utilizing relays to turn on and off a AC motor. However, I would like to control its speed. What sort of shield would I need to use?
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I want to switch the diesel generator from the relay output interfaced between PLC and diesel generator starter for automatic switching. How this can be achieved. Is there any circuit design. Is 8 leg relay of 30A is suitable for this? If your answer is yes. Kindly explain the circuit design and interfacing mechanism to switch the generator for its automatic action.
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kindly send me the Engine starting mechanism of the DG set. I will surely send the circuit for the same. Give me the specifications of DG set.
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I need analysis the ergodic achievable rate in paper " Exploiting Full-Duplex Two-Way Relay Cooperative Non-Orthogonal Multiple Access ". i'm using Matlab 2016a.
analytical base on (33) (34) (35) (36) in paper attach
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Perhaps this article is able to provide some insights about the exponential integral function:
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Distance relays respond to a ratio of voltage and current at the relay location, this ratio is in the form of impedance, as the impedance of a transmission line is proportional to its length. This concept is used for locating the location of the fault in a transmission line, via distance measurement.
Thus a relay capable of measuring the impedance of a transmission line up to a predetermined point is used, known as as the distance relay.
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Because that all the electrical lines including power transmission lines have distributed parameters - resistance, inductance, capacitance, conductivity and impedance. Just their wave impedance does not depend on length.
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During the test of the power swing function in distance relay (Micom p441) using the continuous shots from no tripping area to zone 3 in a specific length (1 second), when I use 20 shots the relay detects it as a fault, but when I use 25 shots the relay detects it as a power swing. Why this happens?
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How does the electrical industry detect faults (LG, LLG etc) in the transmission grid?
  1. Using voltage sag for fault detection & location?
  2. Using overcurrent magnitudes for fault detection & location?
  3. The analysis is performed using voltage/current AC waveforms or RMS (DC equivalent) waveforms?
  4. Which equipment/s are used do we employ relays for this? Is there a relay which detects voltage sags?
Will be highly obliged if someone can answer the above queries. Thank you
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Distance relay is used to detect the fault by line impedance.
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ff
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Dear Ahmet,
The outage probability Po is the summation of t he instants of time Sum dt at which the received signal will not sufficient to give correct received data because of deep fading divided by the total transmission time Tt.
So the Po= Sum dt/ Tt. This is valid for one hop or more than one hop.
In case of intermediate relays, it depends on the signal processing in the relay how far the relay will affect the Po.
- If the relay is regenerating the data, then one can consider that one has two independent hops. The successful transmission probability Ps= 1-Po can be calculated for each hop such that Pst= Ps1 Ps2= (1- Po1)(1-P 02)= approximately to 1- Po1-Po2 = 1-Sum Po
So , one needs to calculate the Sum of Po.
If the repeater is just an amplify and froward device then one has to consider the final received power at the destination after the two hops such that
Pr= G h1 h2 S1, which is the received power at the destination after the two hops with channel transfer coefficients h1 and h2.
The total noise at the receiver Nt= G h2 Nrepeater + Ndes,
where G gain of the repeater, Nrepeater, the repeater added noise power at the input of the repeater and Ndes is the destination added noise at the input of the destination,
So, finally the S/N = Pr/Nt, This ratio will vary with time randomly with time because of fading. The instants where S.N decreases less than certain critical value the data will be lost and outage occurs.
So Po= Sum dt/ Tt. With the help of the statistical channel models then one can calculate the outage probability.
Best wishes
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For research I'm doing, it is possible to convert a cellular relay base station's radiation power intensity to a transmitted power from this cellular station?
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You need a propagation model since the net itself is designed so that in most of the covered area, a user could be reached by more than a single tower.
Even assuming that there is only a tower and you are able to measure only the signal irradiated from that one, the irradiated power depends on the direction
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Please... add project member who relay want to join your project
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Dear Mohammed Kemal ... as you told " If that person interested " .. to know the person is interested or not... we must talk before adding anyone in a project
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Hi everybody, I want to make a rigid endoscope with Hopkins relay system but I have only a little information about Hopkins relay system and lens.
I want to get information about the lens material and design it.
Do you have any information that can help me or do you know the book, article or site that helps me?
Best regards
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Thank you for your help.
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What do you think about the interoperability of Low power wide area IoT devices belonging to different LPWAN technologies? As a subset of LPWAN IoT protocols operates in unlicensed sub-GHz band (like LoRa, Sigfox) while some other protocols operate on licensed spectrum (NB-IoT). How is it possible to make them integrate/compatible with each other? How about relaying both LoRa and NB-IoT through a single gateway?
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Thanks Bendaoud Fayssal for the comment. Undoubtedly, the differences are many, but we should still be able to find a suitable trade-off for the coexistence. Both 3GPP and proprietary protocols sometimes target the same set of use-cases with similar requirements. Cognitive Radios can also be a choice . What if they both follow IPv6 packet formats? Can the packets belonging to both of them be relayed by a common gateway to the network server?
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I think the latest developments in optimal relay coordination are adaptive settings of relays in the presence of Distributed generation. what is the area in which i should do research in pursuing PhD?
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Hi there, my research area is mainly on using probabilistic methods for power system stability. Perhaps, you can use similar concept in your field. Please see the following links which may be useful for you:
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In Underlay paradigm both PU and SU coexist while SU control its power to reduce interference to PU.
In Overlay model both PU and SU coexist while SU know the coding technique used by PU for two reasons, first to avoid PU interference and second to help PU in relaying his messages.
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Underlay and overlay is the coexistence of two signal sources together which are active in the same time ans at the same frequency but have different transmitting powers. In case of the underlay one is very weal and the other is very strong. So the weak will very slightly disturb the strong one. In case of overlay the the overlay is the stronger source and the other is the weaker source. In fact Overlay is the stronger and the underlay is the weaker. The stronger can detect his signal with acceptable bit error rate. The weaker in order to detect his signal he must detect the strong signal at first and then cancel it and detect his signal. It may be similar to NOMA nonorthogonal multiple accessing. Also one can make the underlay signal very wide band by spreading it on this wide band while strong signal is narrow band. In this way one can also detect the wideband signal in existence of the strong signal.
Best wishes
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Detecting if the Neutral Ground Resistor (NGR) is shorted is something that must be checked at the Ground Fault Protecting Relay. The typical way to do this is to inject a DC component and to measure the voltage drop in the NGR. If no voltage drop is seen, it is assumed that the NGR is shorted and the relay trips. I would like to have Wye-connected PTs, used to monitor the quality of line to ground voltage and NGR monitoring with NGR short circuit condition detection at the same time on a 4160 V transformer secondary.
Having Wye-connected PTs may confuse the ground fault detection relay as for the DC component the PTs provide a low impedance parallel path which can be confused with a shorted NGR and this must be avoided.
Is adding a Potential transformers Ground resistor (PTGR) the only way to achieve both things? Wouldn't this affect the reading of the system monitoring the quality of line to ground voltage?
Update: There are also PTs that are build with a capacitor voltage divisor on their primary but I haven't found any operating at 5 kV
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PT can be designed or built in two ways. Like classical two winding transformer (primary winding, which is high voltage side (10, 20, 35, 110 kV) and low voltage side (usually 100/V3, 100 V). Also standard PTs, have more secondary windings, for metering device, for RTUs, relay protection, etc. Second type pf PT is with capacitor divisor, or capacitor PT. On secondary side there is a winding with for creating a secondary voltage of 100/V3 or 100 V. Primary side of this winding is 10 or 15 kV for transmission types of PTs. Today PTs on secondary side gives you voltage for each phase. So it can be monitoring phase to ground voltage and can be used for relay protection and in connection with others phases you can have monitoring phase to phase voltage in relay device, and you can have open delta voltage to see what happened in isolated network.
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Can anyone share the research papers related to adaptive relaying scheme for the AC grid with VSC-HVDC connected offshore wind farms?
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Dear prof, Mohamed Azab
Thanks for your information.
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Sherpa is one of the systematic prediction methods for human error .
What do you think should be done to reduce the human error in testing relay protection?
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Each automatic procedure can significantly improve testing for relay protection system. Using in advanced prepare test procedure it will be reduced possible human errors. In next step, it can be combine the automatic checking of relay protection operation with application. With application, it can be checked operation and reaction of relay for disturbances in power system. Those two steps will for sure improve the operations for relay in power system.
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I'm trying to calculate the queuing time on the relay nodes so as to chose a routing path in a less avg. queue time. My I get any one who works around? I'm using a ns2. Any response is appreciated!
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Olawale E. Olasupo Thanks, I tried to refer the ns2 documentation but no explanation about this is there. Esp from where can I get arrival rate and service rate values if you have worked with them?
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That is suppose there are 2 nodes A and B in a given Network topology. Assuming that we assigned the queue length=50packets for each. Let a number of packets are sent to those two nodes. Here my question is how can I know the number of packets that are waiting in a queue in each nodes so that the next packet should have to be sent to a less queued node? Is there any mathematical formula to determine this if you knows??
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Dear Bekan Kitawm,
I do not know the details of her problem. But I think the Little's Formula for queue Type M / M / 1 can be used here.
See for example:
(See here page 8)
Best regards
Anatol Badach
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The data has been given. I have done the simulation in Simulink. Now i want to use relaying logic for the fault at any Load bus say bus 4. but i am unable to find the load current. Can anyone help me with the load flow analysis of system? No internal impedance of generator is given so i considered to have 0.15 pu of reactance.
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I think the load flow analysis doesn't provide current information. It's all about voltage, power angle (delta), active and reactive power.
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for single relay , theoretical BER is = 0.5*(1- (g/(1+g))^H/2).
g= SNR ( say same for each hop) . g= (mod(h))^2 *E/N ; H= no of hops
as per the published paper- ' End-to-End Average BER in Multihop Wireless Networks over Fading Channels ' in that paper, simulatin result is same (100% same result)as this mathematical expression.
but when I am trying to implementing it in MatLab , result is not nearly same.( difference in BER= 0.01 max) but not exactly same.. why?
can anyone send me Matlab Code for Decode and Forward simulation of cooperative scheme??
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Both the formulas are correct. Note that
  • received signal = transmitted signal * fading coefficient + noise
  • SNR = (transmitted signal power * channel gain)/noise power
So when you write
y = sqrt(P) * h * X + sqrt(N0/2).* (randn(1,1) + 1i * randn(1,1 )),
this means that
  • "sqrt(P)" is the energy of the transmitted signal, "h" is the channel coefficient, "X" is the transmitted symbol with "E(|X|^2) = 1", i.e., mean power of the transmitted symbol is unity.
  • randn(1,1) gives you a zero-mean Gaussian random variable with unit variance (power). Now for non-binary modulations, since your transmitted symbol may be a complex number, both your channel coefficient and noise should be samples from a complex process. Therefore "(randn(1,1) + 1i * randn(1,1 ))" returns a sample from complex white-Gaussian process. Note that the mean of each "randn(1,1)" is zero and the variance is 1. Therefore the overall variance of "(randn(1,1) + 1i * randn(1,1 ))" is 2 and in order to normalize it, we multiply this with "sqrt(1/2)". In this manner the power of "sqrt(1/2) * (randn(1,1) + 1i * randn(1,1 ))" becomes 1. Now in order to scale it properly according to the required SNR, you further multiply this with "sqrt(N0)".
Hence if you calculate the SNR for
y = sqrt(P) * h * X + sqrt(N0/2).* (randn(1,1) + 1i * randn(1,1 ))
you have
SNR = signal power / noise power
= power of (sqrt(P) * h * X) / power of (sqrt(N0/2).* (randn(1,1) + 1i * randn(1,1 )))
= P / N0,
because "h" is simulated in such a manner that E(|h|^2) = 1, and E(|X|^2) = 1. Note that this is the average SNR (the instantaneous SNR will be different because |h|^2 is not equal to 1).
Now in your equation
y1=sqrt(p1).*h_sr.*s1+sqrt(noise_p1).*n_sr,
I presume that "n_sr" is a zero-mean, unit-variance complex Gaussian process. So
noise_p1=p./SNR_lin = p./(p./N0) = N0
is the same as the other equation.
Hope this answers your query.
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In a system, one source (S), one relay(R) and multiple users are connected with a relay, S and R have multiple same number of antennas, however all other users have same number of antennas. One can calculate the SINR for single receiving antenna by users, but how about multi stream transmit antennas from R to users, precoding matrix is considered?
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That's why my consideration is to maximize the rate of one user.
By considering precoding matrix at the user can solve the problem of multiple data stream interference for different antennas ?
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In wireless communication systems relays will improve the performance, capacity and energy consumption of the system, lets say I want to employ multiple relays between the source and destination node, some coding methods i need to employ so that signals will be transfered coherently. My question is that which technique is more suitable to apply, either Precoding or STBC?
Your comments will be highly appreciated.
Thanks
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Dear Saleem,
Some authors use the word 'pre-coder' solely in the context of 'spatial multiplexing', i.e. to maximize rate, while others stretch its use to mean beamforming, i.e. to maximize SNR, as well. I somehow believe you are referring to the latter case and concerned about which method you should apply in order to increase the reliability of your wireless relay system. If by "performing better" you mean the method which yields higher SNR and therefore smaller BER, then the selection between beamforming or STBC depends on the availability of CSI (or lack of such) in your system. If CSI is available at the transmitters, then beamforming is better. Otherwise, O-STBC (or its variations mentioned below) is a better choice. Note that if there is mobility within your system and, as a result, the time selectivity of your channels cannot be disregarded, then, Modified STBC (MO-STBC) is more suitable than O-STBC due to the robustness of the former to time-selective fading. Also, keep in mind that due to the rate-loss inherent to O-STBC with more than two transmit antennas in the case complex constellation is utilized, Quasi-Orthogonal STBC (QO-STBC) might be preferable depending on the SNR range that the system is operating and the modulation order utilized. Best regards,
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I am working on NOMA in cooperative relay networks, i am trying to replicate the results of jouranl paper, where noise power of AWGN is set as -114dbm (3.9e-15 in decimal), as it is very small value, which makes transmit SNR very high and in turns outage probability is always zero. I want to inquire that whether "noise power" is same as "noise variance"?
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Dear M.
welcome,
The standard deviation is sigma and the variance is sigma^2 which is equal to noise power, so N= the variance,
Coming to the value which you gave for the N= 10^-11.4 mw. So the value which you estimated is right.
One important note which you must pay attention for: The transmit power Pt is normally much higher than this value but this power impart large attenuation from the transmitter to the receiver. As an example assume a transmitter radiating 10 mw at 10 meters AS the distance increases the power density will be reduced by distance squared. So, attenuation as high as 90 dBs due transmission loss can occur and the signal level will be as low as -80 dBm at the receiver which is only higher with 34 dB relative to noise. This level may be required at the receiver to achieve the required bit error rate.
I am little bit worry about your sentence: as it is very small value, which makes transmit SNR very high and in turns outage probability is always one
It is known that as the S/N ratio increases the outage probability decreases as the bit error rate decreases!!
Best wishes
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Can distance relay be used for busbar faults?
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Yes. We have adopted a relevant solution for bus protection in distribution systems as part of:
An issue that requires special attention regards the significant voltage drop during close-in faults (as bus faults), preventing the distance relay from determining fault direction. However, this is addressed through cross-polarization (i.e. the use of healthy-phases voltage) and/or voltage memory (i.e. the use of the pre-fault memorized voltage during close-in three-phase faults), commonly adopted in commercial distance relays.
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I want to control the heating element so as to maintain the temperature of the steel plate at 150. I am considering two options. 1. Using a PID temperature controller connected to the heating element and a power supply. 2. Using a relay and a DAQ card with the input of the relay connected to power supply and the DAQ card while the output connected to the heating element. which thermocouple is best for temperature measurement of the steel plate. Anybody with any useful advice
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How accurately do you want to maintain 150C? Steel isn't a brilliant conductor of heat so losses to the surroundings could easily result in temperature differences of one or two degrees across the plate.How thick is it?
If you want really accurate temperature control say to millidegrees, you may have to immerse the plate in vigorously stirred oil and apply the heat input to the oil and not the plate; and at this point the whole experiment starts to get messy (and dangerous). But best wishes with your work!
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I am looking for the design of quadrilateral characteristic-based distance relay.
whether the relay setting for phase and ground distance relay is same or different?
Suggest your idea or some reference materials.
Thank you.
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When you dealing with setting of distance protection you should be aware for setting of phase to phase and phase to ground faults and events. Modern numerical distance relay gives nice opportunities to have wide range for setting. Different setting for phase to phase fault and phase to ground fault must have different ratio R/X for those two types faults. Manuals for distance protection, SEL, General Electric, Siemens, ABB and others you can find on official web.
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How to calculate thermal/heat loss of a control relay?
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A relay has a primary and a secondary which one do you want to analyse ?
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I want to switch to autotuning of the PID values rather than doing manual autotuning. I want to know all the possible resources for that. Please advise.
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Here's a good page on automatic tuning of PID controllers, with references to recent research at the bottom:
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We have a 220/33 kV Substation and 100 MVA transformer, YNyn1, primary of which is 400/1 CT with RET-615 relay and secondary of transformer is 2000/1 with REF-630 relay. For an outgoing feeder earth fault, both the outgoing feeder and transformer secondary are tripping simultaneously on master trip 86A and 86B.
IDMT stages are properly co-ordinated and
The high set earth fault setting for outgoing feeder is 216 A @ 0.2 sec
The high set earth fault setting for transformer secondary is 1600 A @ 0.4 sec
Still the transformer secondary is tripping for outgoing feeder fault. We even checked the phase currents obtained during the earth fault and overcurrent relay pick up settings, but even they are clearly co-ordinated with 0.2 time margin.
What could be the probable cause of such tripping?
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Did you collect all disturbance recording and event list from all feeders and transformer? Those graphical representations of this particular event will give you clear insight view what really happened. Several fact can cause this sequence what you ask. Transformer protection operated because probably exist current flow. Did you check operations of outgoing circuit breaker feeder? Did feeder breaker interrupt faulted current?
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can we consider the ETAP results for relay coordination is real time simulation results.
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I also think like mr. Patel thtt the answer is yes. TCC curves and time domain simulation of faults and relays tripping can be considered as real if the model is accurate. But still there may tricks, related the saturation of CT, errors in CT, VT and relays settings and delays.
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this is regarding relay coordination and ground fault condition.
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Many demerits are there....like switching losses, harmonics generation, need of external triggering...you may refer following paper for further reference.
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I am a bit confused with pesticide half life. As far as I know, it is used for environmental purposes.however, if a pesticide is systematic then the biological process would deal with it during the waiting period but if a pesticide is by conract, dose it have the same waiting period or do we relay on the washing step to remove the residues fron the surface of fruits and vegetables.
If we relay on the weather conditions to degrade pesticides from the surface, do they have then similar time as Half-Life.
Do low, moderate and high half-lives presist in the environment somehow related to the safety of plants in fields, produced for humman consumption or as animal feeds.
Best regards
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It is more to do with persistence of pesticides residues in soil or related environment where they are intended to be used...
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In the attached circuit diagram Relay 1 is always energized. Relay 2 will be energize only if somebody presses either of the switches but with relay chattering relay 2 got energized without pressing the push buttons and started the pump.
question is how relay 2 got energized as there is no path for the current flow other than switches.
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I assume that the push-buttons are rated for the voltage applied or higher. Otherwise arcing is possible and therefore causing a partial path to the relay and causing the chattering.
Also, without the complete diagram, it is difficult to tell for sure so this is entirely a SWAG. Could there be a source of CEMF causing the coil to be partially energized and causing the chattering?
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If we have two-nodes and one relay, where two-nodes can communicate with each other using the help of Decode-and-Forward relay node. How to implement it in two-phase transmission instead of three-phase??
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There are two methods. One is using two-way relay. In the first phase, Source and destination transmit to the relay. In the second phase, relay transmits in the either direction after decode and re-encoding.
Decoding and re-encoding is generally not considered as a phase
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Suppose I have a millimeter wave relay system with one BS, one relay and one UE. During beam training, assuming exhaustive search technique, can the relay simultaneously receive pilots from BS and transmit pilots to the UE for the purpose of beamtraining. The Relay can be considered to be operating in half duplex mode, for example, it listens to the pilots from BS in a band and transmits the pilots to the UE in a different band simultaneously.
If that is the case, is it correct to consider that the beamtraining or the cell search latency for the entire BS-Relay-UE link is maximum of time taken between of BS-Relay link and Relay-UE link?
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Since the relay works in out-band half-duplex mode, it is possible for pilot training for two hops simultaneously.
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Plants communicate each other in a chemical way rather than electronically. Can we use it for human communication purpose? For instance, a transmitter sending message to a plant then this plant relays message chemically to other plant, the chemical message is then converted by a receiver. Any existing research?
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Thank you for your respons. The finding is still immature, references are searchable online in form of documentaries. The bold question is "any existing research?". I think the priority question is still "Is it possible?". Of course in human world, electronic communication is the champion. But other forms have their own benefits.
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i am working on indoor relay in lte-a but i am missing codes to show the improvement of multi-hop relay for indoor compared to single hop.
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You can quickly simulate this using NetSim (http://www.tetcos.com) and figure out the results. It has support for LTE / LTE - Adv
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We have different schemes for the compensation of fault resistance because it affects performance of conventional ground and phase distance relays.
But which are the cases in which the high resistance faults occur? And how many percentages of these faults occur as compared to dead short circuit faults (means the faults with negligible fault resistance or fault impedance)?
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Thera are several cases for high resistance faults in transmission network. High resistance faults always happened only for phase to ground. In my professional praxis I do not have made any analyses for high resistance fault between phases (phase to phase). We can have broken conductor, which fall on tree, and those cases are usually high resistance fault. In addition, you can have faults that some tree fall on lines. It is the same case. We can have faults on specific ground and when the resistance of transmission lines grounding is are not so good. Those cases can be very dry soil; it can be gravel or pebble (small stones) in ground. Also when you have lines across the area where are the ground from only from rock. You can have high resistance faults when some tracks or another special vehicle “touch” the line phase wire. Those cases can be very dangerous for people inside the truck and this fault are also very challenge for line protection. In most cases those faults can be effectively remove only with directional earth faults current protection or with line differential protection and distance protection are not so efficient. In general, those kind of faults are very rear. In my opinion, only few percentages but you must remove them effectively in very short period of time.
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  • Is there one regulator device that can supply at least 1.2 Amps @ 5 VDC from a 9.8 - 14.8 VDC battery and also draw below 150uA in quiescent mode? I am currently using two regulators for this requirement. I must completely cut power to the high current regulator to achieve a 150uA sleep current as the quiescent current of any 1.2 Amp device I have seen is well above 150uA.
  • The high current regulator is powered on for one minute and off for 9 minutes.
  • LM2936 is used for the low quiescent current. 7805 type is used for the high current regulator. The high current regulator is powered on and off by a PVG612 optical relay as this device has very little off state leakage. This designe is from 17 years ago. Surely now there is a single device that can do all this without creating so much heat.
  • This regulator system is used to power a microcontroller that charges batteries and controls the telemetry devices for my agricultural research project published here. Thank you in advance.
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There are quite a lot available from Linear Tech, this page allows you to select by parameters, I've included shutdown current and set a max of 1uA:
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I am considering putting a ground relaying scheme for a generator. Does the specification of the transformer play a role in the generator neutral current?
Any suggestion or reference is highly appreciated.
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Generator neutral current would not be affected for the balanced loading of load, the transformer. In unbalanced condition(phase, amplitude or impedance of load) depending on rating of load(transformer) the return current(neutral current) needed to flow, or would be, depending on rating of transformer(specifications)....
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I am working on a Power system transmission lines protection, i need a distance relay design for analysis...
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Qasim,
there is a much appropriated book for you. The author is famous Siemens engineer Gerhard Zigler he write a book “Numerical Distance Protection: Principles and Applications”. In book, you can fine nice description of distance protection functions. Therefore, with these formulas you will be easily implemented and designed your line distance protection in model. After you can attached this model on each lines in IEEE 9 bus system.
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I have a DC-DC converter (input rating 9-36V/5.9A and output 12V/3.4A). I am supplying power to this DC-DC converter using a power supply rated (12V/10A).
This power supplied by this DC-DC converter (12V) is then relayed on three 24AWG conductors (max current capacity of 577mA).
What should be the rating of the fuse which I should be placing at the input of the DC-DC convertor?
Help or suggestions would be greatly appreciated.
Cheers,
Shri.
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Dear researcher
the amount of fuse value completely is in relationship with your load. For example if your load value is small (high current will be on that), so because of high value of current on load this strongly effect on input current. For example for a conventional boost converter(Iin=Io/(1-d)). It means for duty cycle=0.5 for 1A for load current you will have 2A as input current. So you should consider the maximum value of load current and calculate your input current accordingly and then put a fuse with a bit haigher that your input current.
Sincerely
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In the conventional start/stop relay circuit, an additional ("holding") contact is connected in parallel to the start push button.
But what do we do when there is no such an additional contact? Or if there is no contact at all (for example, instead of a relay there is a solenoid)? Can we still make a "relay latch" with simple means?
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yes quite simply using a push-to-hold button (or a spst switch). Pardon my joke but I could not contain the joy ..
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I hope to make a compact electric circuit to control my module.
Because module size is very small (diamter=11 mm, length=30 mm), I can't use general timer relay.
My module operates as follows.
Signal input (Switch on) > first part actuating(latching part is melt) > time delay (for example 5 sec) > second part actuating(latching part is melt)
I can use just one signal, not two, so I try to actuate second part by delaying turn on timing. In case of the macro size system, it is very easy condition but size limitation interrupts me. As I guess, some IC chip or timer(ex. NE555) should be utilized like this case. Or is there any micron timer relay?
I will make a custumized PCB after fixing electric circuit.
Best regards
Dongkyu Lee
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Hi Dongkyu Lee,
Have a look at the data sheet for the MIC1555 This can be used to give a delay similar to the 555 timer but are much smaller and need fewer components. You could cascade 2 of these together to give you the timing you need. For the power switching, again for compactness i would recommend using an N-channel Mosfet. They can handle very high currents (but DC voltages only). If you are interested in doing more of this kind of electronics I would highly recommend looking at the atmel 8-bit micro-controllers, used for example in the popular arduino boards. Having an "on board computer program" for switching and controlling pins, gives almost limitless flexibility, and the AVR studio system is really first class!
For PCB manufacture I would recommend PCBway.com, they are so cheap that its not even worth prototyping, particularly for such small components! (and recommend using solder paste for surface mounted parts!)
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In order to ensure the best QoS in cooperative systems, which relaying protocol should be preferred : Regenerative type (Decode-and-Forward : DF) or Non-Regenerative type (Amplify-and-Forward : AF)? Kindly provide some reference(s), if available. TIA.
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DF is preferred over AF to ensure best QoS in cooperative system. Also, DF gives a better BER performance as compared to AF. On the other hand AF relaying technique is much simpler and better in terms of less complexity as compared to DF.
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logic for implementation of rocof relay using digsilent .So that our protection scheme for 3MW embaded generation work effectively
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Dear Sadiq
In DiGSILENT you have numerical rely ABB REF 542 or you can download the library from www.digsilent.de if you are licenced user.
In that relay ABB REF 542 you have ROCOF function df/dt> in 5 steps. See the attachment.
Srete
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In Pakistan currently we are facing black outs in many areas due to false tripping of relays caused by flash overs due to severe foggy weather in the areas. Your kind suggestions are most welcome.
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If the fog is affecting the relays, then they should be put into a sealed dry container or room.
If the fog is affecting the 500 V overhead lines, then you have a bigger problem easily solved by using underground cables rather than overhead lines. But that would be very expensive.
Another possible solution would be to have a greater distance between the individual overhead lines so that the arcing is less likely to happen.
I think that here in the UK, we automatically reconnect after a line drops out for the first time. You need to have timer to prevent a second re-connection in the case of a genuine shorting.
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I dont have question i only say thanks a lot Dear Prof Dr. ( Emil Roduner).
Relay I understand (why nanomaterials are different) thanks a lot for your paper thanks for you
I think this is more important to understand the nano size
DOI: 10.1039/b502142c
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HI there,
The main reasons why nanomaterials show properties so different from those of the bulk are: Surface effects: atoms at surfaces have fewer neighbours than atoms in the bulk. Because of this lower coordination and unsatisfied bonds, surface atoms are less stabilised than bulk atoms. For nanomaterials, not only their chemical composition, but also their morphological properties and surface properties determine their characteristics. These properties do not only differ in comparison to the corresponding bulk material but also between different nanoforms of the same substance. To more information see following link: https://chemistry.stackexchange.com/questions/61377/why-do-nanoparticles-have-a-different-color-than-their-macro-counterparts
Regards,
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I am interested to know the latest trends adopted for distribution system protection. I would be very thankful to you for answering the following questions;
1) What are the modern trends used in various power distribution networks for protection?
2) How is protection coordination maintained in modern distribution systems in the presence of distributed generators?
3) Are the settings of relays kept fixed or changed as per prevailing power system conditions?
4) Does adaptive protection exist in the modern distribution systems?
Thank you so much for your contribution to this thread.
With best regards,
M. N. Alam
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SCADA (Supervisory Control and Data Acquisition) System . 
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I'm working on mitigating frequency shift wireless communication links suffer from in case of the two communicating parties are moving relatively to each other (Doppler effect).
In some cases frequency shifts happen very rapidly, so I need to know what are the practical limits of an oscillator following these changes if they are already determined.
e.g. is it possible to program a VCO to shift its frequency one step up/down every 4 microseconds? or will the VCO, or oscillator, fail to respond in such short period?
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Yes, one reference clock period is 2 us. If the loop gain is properly set, the dampening may be critical and the overshoot-undershoot minimized. So of course this leads to another part of the question, after frequency clock occurs, phase synchronization time or phase stability must be added. Ideal, it is zero. Hence, how much time and to what degree of phase error will you accept?
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I am confused about the value of power supply of the ICs uln2003 and uln2004 which drive some relays. I have seen different opinions in the internet or the datasheet of the ICs. Moreover the maximum input for the uln2003 is 3V and for the uln2004 is 8V? Can someone help me?
Thanks a lot in advance!
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Hello Valentina,
both the ULN2003 and the ULN2004 can switch a maximum voltage of 50 V, and a current of 500 mA. However, you have to be careful not to exceed the maximum junction temperature of 150° C. With a thermal resistance between junction and ambient of 70°/W (for the through-hole package), and, for example, an ambient temperature of 30° C, the sum of the power dissipated in all drivers of one device is limited to less than about 1.7 W. Due to the relatively high saturation voltage, this can limit the output current to less than 200 mA if the application can cause all seven drivers to stay in the ON state for unlimited time.
If this is a problem in your application, better use drivers with MOSFET outputs providing low resistance (< 50 mOhm) in the ON state, or discrete MOSFETs which can be driven by the outputs of the dsPIC directly. However, if switching inductive loads (like relay coils) with discrete MOSFETs, you have to provide free-wheeling diodes, too.
The main difference between the ULN2003 and the ULN2004 is the value of the resistor between input and base of the darlington transistor. The ULN2003 (with 2.7 kOhm) is intended to be driven by logic devices powered by 5 V or even 3.3 V, i. e. TTL logic and TTL compatible CMOS logic, while the ULN2004 (with 10.5 kOhm) is intended to be driven by CMOS logic like the 4000 family with voltages up to 15 V. The limiting quantity for the inputs of both devices is the maximum input current of 25 mA; this current will never be exceeded with any output voltage of arbitrary logic families.
Instead of issues with maximum values, the point here is that the time it takes to switch a transistor off is much longer if the transistor was heavily saturated before, i. e. if it gets much more input current than necessary for the actual output current. So, if you would drive a ULN2003 with 15 V input voltage it would switch off slowly, and if you would drive a ULN2004 with 3 V input voltage you could switch only small output currents, in the order of a few 10 mA.
I hope this helps.
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Hello everyone,
I have chosen a relay which has max switching voltage 440V rms(datasheet value). However, the particular relay must  withstands 500 V rms minimum. Is this going to cause a problem to my circuit?
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I agree with Dr Zekry. The risk you run into, by using a relay specified for lower voltage, will be arcing. It may shorten the life of the contact points, or even arc internally before reaching the points. The internal arcing risk is probably negligible in your case. The difference between specified voltage and operating voltage is not extreme. Still, best to always operate inside specified values! Voltage and current ratings both matter, for relays.
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i have done phasor estimation of voltage and current quantities.
i have attached the code for quadrilateral.
and i don't know how to give trip signal, like what should be coding?
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As you mentioned you have done phasor estimation of voltage and current. I hope next step should be of finding impedance measured by relay by using phase and ground distance elements. If the measured impedance (R and X cordinates on impedance plane) lies inside your quadrilateral zone, then develop a logic that it should generate 1 or 0 as output (as per required to open breaker).
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What are the advantages of half cycle fourier transform over full cycle specifically for distance relaying scheme.
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There are also some statistical advantages of using half cycle dft. Indeed, it can be shown that the half cycle dft corresponds to the maximum likelihood estimator of the phasor. Statistically, it is known that the maximum likelihood estimator is asymptotically optimal (no biais + variance=Cramer Rao lower bound)
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*Current system I am using:  3i 4 laser, CSU-X1 system with an Evolve 512 camera running of off a Zeiss Cell Observer.
Interested in if anyone is using a relay lens to fill the chip with the new large format sCMOS cameras.
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Hi Magdy
The older CSU-X1 optic vignettes produces an image that will not fill the Flash 4.0 Chip and you will also see field effects on the edges where you don't have the same illumination.  If you put optics in front of the camera you could magnify the image to fill the chip on the Flash 4.0 camera... losing resolution but reducing field effects. 
In any case, what I have learned from Vendors is that you are better off just autocropping the image in software so you maintain resolution but don't have to save the unused "black" space in each image and also crop out field effects.
G.
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The existing system already use df/dt relay but the system still collapse.  
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Well, given it's a matter of money, not of time: building the measurement equipment on your own might be worth some bachelor's/master's theses. Maybe you'll find 'sponsors' regarding the potential improvent in power supply quality...
Wish you success