Relay - Science topic

How can I control the centrifugal speed of 4, 6 or 8 bogie wheels on a locomotive? There will be an encoder on each wheel so the circumferencial speed is known. This changes when a curve is approached in the railway line. In the picture above, the large wheels represent the railway line. One bogie wheel can be adjusted in and out to represent a change in circumference of the wheel. The object is to prevent slip and slide of the bogie wheels.

Simulating a distance relay using MATLAB Simulink involves creating a model of a power system, implementing distance relay logic, and testing its performance under fault scenarios. Here's a summarized step-by-step guide:

Ensure familiarity with power systems, protection schemes, and Simulink for successful distance relay simulation.

see this

https://www.mathworks.com/matlabcentral/answers/697450-build-a-relay-on-code

STOP !!!!

100 A is a high current, you cannot cut it so easy. Every time you cut the current , a self-inducted voltage (depending on the inductivity of the circuit), will appear (which can destroy a lot of electronic parts), if not properly clamped.

This approach ( to control the load by ON/OFF of the power supply with the help of the relay) is not the ideal choice.

On the other hand NI DAQ means : National Instruments Data Acquisition

This is an electronic module designed to measure and store digitally a signal (voltage signal) NOT to control some other module.

To correctly design the circuit , one has to know exactly the specification of the system.

التكرار والتصحيح والاعادة هي الطريق الاسلم والافضل للتعلم

According to me, micro processor based load shedding control are more easy and reliable to use, could refer my papers.......

Dear Bashar

So I am, I agree with Pablo Gómez

Best regards

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:

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.

IDMT selection time, should be higher than HRC fuses ….

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

I apologize for not knowing

Hi Milton Kumar Kundu ,

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. :-)

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

You can see my papers there I done matlab coding for Graphs. I think you can find your answer.

Dear Mikhail Pylnev ,

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.

My email is aaazekry@hotmail.com

Best wishes

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.

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!

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?

Thank you,Dr Muhammad Ali

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

Could you check my papers, reply to your question Vishaka Basnayake

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

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

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.

Nakagami-m is generalized, however, recently Rice university researchers proposed through experiments the Rice distribution.

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.

Hi Nguyễn Xuân Diệu ,

Perhaps this article is able to provide some insights about the exponential integral function:

https://www.mathworks.com/help/symbolic/ei.html

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.

Maybe this paper can help you

Distance relay is used to detect the fault by line impedance.

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

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

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

Dear Mr. Magdy Eisa Saafan

Thank you for your help.

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?

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:

https://ieeexplore.ieee.org/abstract/document/8036264

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

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.

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.

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?

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

I think the load flow analysis doesn't provide current information. It's all about voltage, power angle (delta), active and reactive power.

Hi Aneek Ghosh ,

Both the formulas are correct. Note that

So when you write

y = sqrt(P) * h * X + sqrt(N0/2).* (randn(1,1) + 1i * randn(1,1 )),

this means that

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.

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

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.

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!

A relay has a primary and a secondary which one do you want to analyse ?

Here's a good page on automatic tuning of PID controllers, with references to recent research at the bottom:

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?

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.

Many demerits are there....like switching losses, harmonics generation, need of external triggering...you may refer following paper for further reference.

https://www.ijert.org/download/9343/review-on-fault-current-limiters

It is more to do with persistence of pesticides residues in soil or related environment where they are intended to be used...

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?

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

Since the relay works in out-band half-duplex mode, it is possible for pilot training for two hops simultaneously.

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.

You can quickly simulate this using NetSim (http://www.tetcos.com) and figure out the results. It has support for LTE / LTE - Adv

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.

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:

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)....

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.

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

yes quite simply using a push-to-hold button (or a spst switch). Pardon my joke but I could not contain the joy ..

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!)

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.

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

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.

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,

SCADA (Supervisory Control and Data Acquisition) System . 

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.

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.

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).

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)

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.

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