How to make a Softstarter and why it is sometimes mandatory to use!

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In this small project we will be having a closer look at appliances that require a softstarter in order to properly work with a limited output current system. The shown appliances in this project include an inverter, a boost converter, a power supply and a motor. We will find out why a big inrush current requires a softstarter and how we can build a simple circuit that can do this job. Let's get started!
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Music:
2011 Lookalike by Bartlebeats

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7 май 2024

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Комментарии : 1,1 тыс.

@monrax 4 года назад

GreatScott: How to make a softstarter Also GreatScott: That's a subject for another video

@rogercoulombe3613 4 года назад

Motor controllers are typically another beast entirely to the circuit shown in this video. It makes sense to separate them

@santi308 4 года назад

GreatScott: JLC Pcb... blah blah blah. Also GreatScott: *Do circuits with Perfboard*

@aged_mozzarella 4 года назад

How to control motors and softstarters for them. Pls

@jaycool5978 4 года назад

@@aged_mozzarella depends how you want to control them and the power required for them. Often 1 uses a motor driver. H bridge is a configuration of Mosfets. Another awesome motor driver is a Sabertooth 2. Look into them see if they're what your looking for. Often they can be controlled at logic level around 5 volts, and many configurations accepts PWM, which is very useful for varied RPM applications. Some can be controlled from a RC receiver.

@aged_mozzarella 4 года назад

@@jaycool5978 Thanks, but the thing I always struggle with is the controlling of the h bridge or other configurations. I am not very sure about the relation between frequency and duty cycle. I couldn't really find anything on the internet that'd explain this

@Metroid1890 4 года назад

Your content always saves me and my teammates right before working with some power electronics, you're a lifesaver

@greatscottlab 4 года назад

You're welcome :-)

@KerbalLauncher 4 года назад

Make sure you employ high side switching.

@Metroid1890 4 года назад

@@KerbalLauncher By High switching you mean actually connecting the mosfet before the relay?, also I wonder if this could work at 24V aswel, since the battery we are using has a reference there

@KerbalLauncher 4 года назад

@@Metroid1890 No, I mean don't even use a relay. See the datasheet for this part: www.analog.com/media/en/technical-documentation/data-sheets/LTC7004.pdf Page 12 details inrush current limiting methods.

@Metroid1890 3 года назад

@oH well,lord! even so it seems pretty unreliable, I like the way he explains it by applying raw theory in simple circuits

@ParenteGrande 4 года назад

During my education we were taught about this. We were taught it was called a Startup Power Spike and most electronics are designed/engineered to reduce this but normally they remove the circuits in production to cut costs. I haven't done any of this in over 20 years but I still have my textbooks and notes. I miss tinkering with circuits. Thanks for the memories and the great work.

@akshaykumargautam5289 4 года назад

"stay creative " is the best dialogue you say. Keep up the awesome work

@jakerezac9088 4 года назад

I love seeing these smaller but still very useful circuit projects. This is gonna be super helpful on my next project!

@erygion 4 года назад

I love the solar system stuff, when I have my own "Lab" I'm going to do my best to power it in this way. Great video!

@TheRealGlennCooper 4 года назад

I really love the way you deliver content. For someone coming at this with a reasonable technical background, you deliver very relevant information in a very easily understood way. If I could make one recommendation it would be this: Don't change a thing!

@gerardosandoval9163 4 года назад

Man you're amazing, I spend part of my breakfast watching your videos, I find it clear and easy to understand thanks from a mechatronics engineering student.

@travispulley8899 4 года назад

I enjoy these videos so much! Your presentation is consistently excellent and sufficiently detailed, and with very good production

@gladosai4354 4 года назад

Human, I understood everything you said. Because it is science!!!! You are my favorite youtuber human!!!

@hashvolting 4 года назад

Send wheatley to my home made ranch

@gladosai4354 4 года назад

@@hashvolting ok then... But when that idiot is on his way... He is gonna be like a meteor

@joopterwijn 4 года назад

Are there other kinds of RU-vidrs then “human”... 🤪🥴

@APerson-mv7td 4 года назад

where's the moron?

@hashvolting 4 года назад

@@joopterwijn did you read his name?

@lanreakerele4375 4 года назад

GreatScott is such a good teacher for learners to learn about something important

@ambaro0887 8 месяцев назад

I find these lessons very therapeutic and mind soothing..💆‍♂️

@aidanwansbrough7495 4 года назад

This was really interesting, love how clearly you explain things!

@rallokkcaz 4 года назад

Hey I noticed your videos have been absent from my feed for a very long time! Please keep making more content like this, it's super awesome as a hobby electronics nerd to see a master at work.

@dnyaneshvarsalve 3 года назад

I like the way everytime you write down and show us the practically calculated values of resistance, current and voltages

@shaileshkullal11 3 года назад

Why are u so gentle and genuine person? BDW i had this problem 4yrs back, while designing pwm controller for big dc motor drive. I've just use few passive components & added some start delay in microcontroller code, which was initiating pwms to drive H bridge.

@lokeyyyy 4 года назад

"I will see you next time" was bit energetic this time 😀

@SirDella 4 года назад

It sounded like someone was playing with the pitch knob xD

@_FRANK_LIN 4 года назад

But never seen

@wavegreen 4 года назад

autotune haha

@lokeyyyy 4 года назад

@@wavegreen hahaha

@Wurstbam92 4 года назад

Sounds like demolition Ranch 😂

@EngineerNick 4 года назад

I wouldn't have been able to design so many of my projects without this channel. Thanks for another great video :)

@stask85 3 года назад

Got exactly these problems currently. You explain the problem and solution VERY well. Thank you!

@pranavasthanaDelhi 3 года назад

I just completed this circuit and it works like a breeze. I was trying to run a dc motor using atx power supply boosted by a boost converter (12v to 24 v). Initially, due to inrush current, atx power supply was getting shut down but now it works well. Thanks Scott!

@AKSnowLeopard 4 года назад

Most people: This electrical device doesn't work, I'll toss it and get a new one. Electrical engineers: Hold my beer...I'll make it work.

@Minitoys59 4 года назад

because obviously we are always holding a beer ;)

@caffeinatedinsanity2324 4 года назад

Drunk science for the win!

@JerryLee.. 4 года назад

Boom!

@satibel 4 года назад

- "The plug started sparking so I threw it" - just change the plug and the cord, dammit.

@MoxxMix 4 года назад

How about not putting unnecessary comments.

@fifaham 4 года назад

You may use variable R2 and R3 to adjust the time delay for charging and discharging the delay circuit thus making it adapt to different circuits configurations. Good job.

@tucker934 3 года назад

Just built this for a WW2 dynamotor, and it works great, I was trying to find something to limit the current so that it’s not hard on a PSU if I ever get one for it, I will say your schematic is very well made!!! Thank you very much GreatScott!!!

@gavinpearcey 4 года назад

I enjoyed this small project, and learned something about soft starters and inrush current. Thanks for the great video!

@pau1976 3 года назад

You can also use a coil in series and a protection circuit to discharge it safely ( diode and small resistor ). It's quite an easy and simple solution. Besides, you can also add in parallel a capacitor to with a resistor move all the high frequencies back to the source. These are pretty simple strategies most power supplies use.

@nick86i Год назад

I think you need a pretty big coil made with very thick wire that can handle a few tens of amps required by such an inverter and maybe it's not suitable for an inverter

@zolatanaffa87 4 года назад

You say: "talking about electric engines.....but this will be subject for another video". Exactly what I wanted to ask you, perhaps using a circuit that excites the relay at the start, only for the time necessary, to avoid the continuous excitation of the coil, which could interrupt and generate malfunctions. thanks in advance for future projects and for sharing your knowledge

@alejandrodelabarra2838 3 года назад

Very tidy. I could never do your extremely tidy explanations. Congratulations!! Thanks for sharing your knowledge and experiences!!!

@jstagzsr 4 года назад

ive been on a kick lately of taking apart every piece of electronic equipment i have laying around my house not in use and mining it for all its little components. Watching your videos give me so many ideas for what to do now with this box of random parts.

@maciekgucma4756 4 года назад

Great ! Im waiting for motor soft starter description!

@Miata822 4 года назад

Good video on a common issue. I made a similar circuit several years ago for use on a 70A 24VDC set of motors I had to start with a 100A power supply. I really had to let the motors get well started before applying full power. I used a large high power 3ohm resistor and an electronic delay-on-make relay switching a larger relay made to withstand constant use at high current and temperature. It worked well. I've seen a guy build a similar device to start a helicopter jet engine. On mine, since this was used on a commercial project, I had to use modular components to allow for field service. I also included a one-shot temperature limit switch and yet another relay to ensure that if the time delay relay failed the big resistor couldn't overheat and cause a "thermal event" (what we called fires back in the day). I've also used NTC thermistors on things like 10-15A blowers that weren't a threat to the power supply but provided less of a challenge to my customers' often overtaxed circuit breakers. You want to choose thermistors carefully and use them fairly close to their rated power so that you get minimal voltage drop over them in steady state use. I look forward to your next soft start video.

@Miata822 4 года назад

VIPIN LADWAL if you enjoy these videos and learn thing from them you could become a patron and not always be 5 days Late :)

@007hansen 4 года назад

@@LAZYLONER- and @Bill Kerr, this abo theme certainly is the next era of capitalism. Call me names but I prefer the single deposit.

@victornpb 4 года назад

One time I used a toaster in series as a current shunt to soft start a compressor

@Miata822 4 года назад

@@victornpb Ha! Perfect.

@victornpb 4 года назад

Not everyone has big power resistors at disposal, except they do, 900W toaster worked perfectly!

@justsean5160 4 года назад

Really cool :) This has been something I've been interested in for a long time, but haven't sat down to learn anything yet. Thanks for the video, it was great! I hope your comment about motor soft starters comes true.

@princebanini 4 года назад

awesome video. love how you explain all the parts and stages involved

@architt4331 4 года назад

I have absolutely no idea to what softstarter is, but I still watched your video as it is always very entertaining.

@CoffeeConsumer643 4 года назад

soft starter slowly increases the power input to the device that you connect it to its used with motors to control their start and make sure the machine wich has the motors doesnt malfunction one it is started up

@dartysengineering7275 4 года назад

Hi GreatScott, hope that you will very soon make a softstarter for ac motors because my lathe has a 10kW motor and trips the breaker every now and then and my dad doesn't really appreciate the flicker of the lights at the beginning. keep up these awesome videos!

@millomweb 4 года назад

Use a star-delta starter for the lathe.

@dartysengineering7275 4 года назад

@@millomweb point is it's a 230/400v 3 phase motor and it is already wired in star because every winding is only suited for 230v but if you have any solution i'll try

@millomweb 4 года назад

@@dartysengineering7275 I can't say you're making sense !!! 400(415)v 3ph motor and then say each winding only suited for 230v ? Do I detect you've connected a neutral wire to the windings ? If so, try putting a switch in the neutral - turn the neutral off for starting and on again once the motor's running with minimal load. I'll have to think about whether you're actually running the motor on full voltage as you have it like that !

@michelfeinstein 4 года назад

Years ago I wanted to make one like this, but with reverse-voltage protection as well and only solid state components, no mechanical relays, good job.

@patazertyui 4 года назад

The issue is clearly explained, thanks for this great vidéo!

@acmefixer1 3 года назад

There should be a 1N4004 diode across R1, with cathode band to +12V. This will immediately discharge C1 and 'reset' the circuit if the 12V drops to zero. Thanks for the great video. 👍

@cdrive5757 6 месяцев назад

Across R1???

@silverjohnson3163 4 года назад

Could you use an inductor to initially slow the inrush current and then when the magnetic field is setup allow all the current?

@silvestrenet 4 года назад

Thanks Scott! I'm going to implement this project circuit.

@anikidwolfy 4 года назад

greatscott, love your videos, half the time im lost with the jargon but always good to watch.

@ahmetzekiuslu3331 4 года назад

Nice video. Don't forget the A class amplifier. :)

@DIYBill 3 года назад

Audiophile grade

@DIYBill 3 года назад

@GreatScott!!

@Sousanators 4 года назад

Slight error with your RC time constant: The resistance seen by the capacitor is the thevenin equivalent, not the series charging resistor. Your time constant should be 0.5s, verified in simulation

@Nic7320 4 года назад

He overestimated it, but that's better than underestimating it. Still, 0.5s is still much longer than the RC delay needs to be, since the input transient he measured is only 15 ms and there's more delay starting up the power converter. But he also made another *simplifying* assumption, when he used the capacitor ESR to estimate the input transient. The MPPT output impedance, and the wiring resistance, and the capacitor's ESR all limit the current charging the input caps.

@keithatkins9394 Год назад

@@Nic7320 Smart Alec!

@Cinemaaereo 4 года назад

What an excellent explanation! Thanks, here from Brazil.

@Minimalist11Guy Год назад

Thank you so much for the well-presented RU-vid. I need to know a lot about soft starting as I am using four 3-kilowatt quartz infrared heaters, that can be switched with a remote controller, to one, two, or three kilowatts. I think that they all need a 16 Amp type C, circuit breaker. The standard circuit breaker trips immediately. On further research, I find that with a soft start, the extremely expensive heating tubes will last 30% longer. Now back to my experimenting!

@lolkusus 4 года назад

7:46 in this case time constant is actually C * (R2 parallel R3)

@AnotherBrokenToaster 4 года назад

This is great, I like your basics videos more than large projects. But you made a mistake with the time constant, the equivalent resistance would be 50k because of the other resistor going to ground, which would give you a time constant of 0.5s

@squareone2520 4 года назад

Isn't that accounted for since his time constant was in relation to an applied voltage of 6V?

@JotaFaD 4 года назад

@@squareone2520 The time constant does not depend of the input voltage.

@AnotherBrokenToaster 4 года назад

@@squareone2520 It's kind of a trade-off, the voltage becomes 1/2 but the resistance is 1/2 also so it charges twice as fast. You can see at 8:38 that discharging takes twice as long as charging(because discharging uses only the 100k resistor connected to ground) and you can also kind of measure from the horizontal divisions(1s at 8:38) that the time constant is 0.5s when charging and 1s when discharging.

@giggletub 4 года назад

Excellent and informative as usual. I'm looking forward to the motor soft start video.

@stupossibleify 3 года назад

So many concepts in a single video, thank you!

@rockyrivermushrooms529 4 года назад

I would like to see you make a VFD!

@vijayendirangiridharan6113 4 года назад

Greatscott : "don't hesitate to check JLC PCB....for their fast production capacity and delivery times!!!" ALSO GREATSCOTT : "MAKES HIS OWN CIRCUIT BOARD.".....TOTALLY SAVAGE🤯🤯🤔

@tunahankaratay1523 4 года назад

@@vojtadeges720 tru

@ZsomborZsombibi 4 года назад

PCB is useful *after* a dev board proves the circuit really works. If it does, I always order a PCB for a reliable, small, long-life, mountable item.

@tunahankaratay1523 4 года назад

@@ZsomborZsombibi 2expensive4me

@tunahankaratay1523 4 года назад

@Chris Russell Yeah true. The biggest problem is shipping for me. The shipping is $20+ and I usually need only 1 board. But I love SMD soldering too and I hope I can get a proper etching setup at home.

@artbyrobot1 4 года назад

@@tunahankaratay1523 all you need is a laser printer, an iron, some transfer paper, and some white vinegar, salt, and hydrogen peroxide and some copper clad. not hard bro

@gregoriglc Год назад

Really good study of the transient state in the inverter. Good design for the relay timer as well. 10/10!!

@ghulamnabisahito1588 3 года назад

Great work. You explain every part of the circuit with examples.Keep it up.

@BladeforgerKLX 4 года назад

I love it! If you can expand this to an A/C circuit, that would be great! When a refrigerator (for example) powered by an inverter hooked to backup -power-supply batteries causes the inverter to shut down, that's a real problem. Yes, a larger (and more expensive) inverter is one solution; however, some type of soft starter is a more elegant solution. THANKS!!!

@josephmagniez9580 4 года назад

Nice video, thanks:) It would be interesting comparing this solution with another that uses a MOSFET as the main switch to reduce even more the power consumption of the circuit. With a 12V DC link it shall not be a huge challenge for you ;)

@vaseemmehrancp9372 3 года назад

Unlike the other channels I am watching, I consider your videos like reference study materials 👍 Good works bro

@FirstLast-vr7es Год назад

Extremely useful! Thank you! I have been in need of a soft start circuit for tube amps. Lots of capacitance on the front end, and it can be a massive current surge at turn-on. I have a few 220uF 700V film caps, and they pull so much current on power-on that they have smoked some pretty beefy resistors that could easily have handled normal current draw. I can also use this for loudspeaker delay circuits. You explained it very well.

@Alex0474 4 года назад

When you’re trying to make an arc lighter using advice from a GreatScott video but get a notification about a new video so you just go watch that one instead...

@jorno1994 4 года назад

stick with the NTC but use it with the bypass relay. it's exactly what high end computer PSUs do nowadays to get over 90% efficiency ratings.

@devrim-oguz 4 года назад

It would still have the problem of remaining hot.

@1Hippo 4 года назад

@@devrim-oguz Should not be a problem, because the NTC already cools down when it is still running, but the bypass is engaged.

@Nathan0A 4 года назад

@@devrim-oguz depending on how fast the caps discharge, perhaps while the NTC is still hot, the caps are still charged and inrush is limited this way? It seems like the best way to do this would be to have a circuit that isolates the caps, soft charges them for a second, and then uses a multi throw relay to disconnect the soft start circuit from the caps, connecting caps to main circuit, and connecting power to main circuit at the same time

@soupflood 4 года назад

That would still be defeated when the appliance is connected and disconnected in a matter of seconds, leaving no time for the thermistor to cool down.

@aarriikknn33ll 4 года назад

Ali Devrim OGUZ yeah no shit, there will be some energy loss but it will get less hot.

@scottt5822 4 года назад

After watching your video's I feel like making something really cool... but then I come back to the reality that I only know how to change the batteries in a torch. I love watching your video's. They inspire me.

@shouldbewillbe2813 3 года назад

Such a miniscule thing, but so important like matter of life and death of electronic devices and components !!!!! Thank you so much for the insight Scott !!!!!

@ancapftw9113 4 года назад

Usually, your charger and inverter are both connected across the battery bank. You can also add a supercap to deal with fast, high amp loads like motor startup. Usually this would be how you deal with high amp draw. Not sure why it isn't working in your system. Is your inverter tied directly into your inverter without batteries?

@Nic7320 4 года назад

Victron MPPT controllers has over current protection on their DC output that doesn't like high initial surge currents. That particular 75V/15A solar controller only provides 15 Amps output anyways, not nearly enough for that 600 watt inverter at full load, which will draw about 60 Amps. So let's assume he using it as an example of a high input capacitance load for illustration purposes. I'm in a similar situation; I really like the diagnostic histogram panel the Victron MPPT controller provides on the bluetooth interface, so I put some of my low current items on the Solar DC output. But, like you point out, my 1200 watt Victron inverter has to go directly to the battery.

@Videohead-eq5cy 4 года назад

I was not paying attention till I heard "my final solution"

@anotheruser9876 4 года назад

And some say Germans don't have a sense of humour.

@gunnaralv 4 года назад

Dark...

@JavaMac08 4 года назад

Came here to see if anyone else noticed 🤣

@frankescu 4 года назад

And for my final solution... came looking for this

@artbyrobot1 4 года назад

he wasn't talking about jews when he said final solution

@jackraves7363 Год назад

🙏 i did enjoy the solution to the current switching problems, I also liked your over-all explanation 👍

@BirdyBenJedi 4 года назад

Great Idea, I use this kind of automated system already since about 20 years for powering on transformers (fuse switched off sometimes) and yes, for PC's also. They have with their switching power supply also a lot of capacitance within their infeed circuit. Sometimes there are quite big sparks at the switch or even at the plug itself. One day in very past I even lighted up a fire in the socket while plugging in such a PC - cable. The socked was dirty, may have had also some invisible oil inside. The spark caused by that capacitance at the plug had been enough to light that oily dirty thing within the socket up and a great flame came out of the socket against me. That experiences caused me to solve that kind of risk.

@vega1287 4 года назад

"the post apocalyptic inventor" did so ething similar but he used a 555 timer , but hus cirquit was also made for mains voltage

@vega1287 3 года назад

@Michael Francis ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-_pEmpvcNmXg.html here you go you fond thr schematic at 2:12

@eritronc 4 года назад

I think is better to use an p-channel mosfet, is more power saving...

@davidjrb 4 года назад

This is one of your best videos to date. Thank you so much for sharing

@greatscottlab 4 года назад

Thanks for the feedback :-)

@speedsterh 4 года назад

I agree. Very well explained, and solves a problem that is often seen

@alansmith2203 3 года назад

would love to have your skill set. Fascinating and detailed. Good job, sir.

@guerrillaradio9953 4 года назад

Would a large capacitor/inductor pair, with the inductor in series on the supply side of the capacitor, solve the problem almost as well? I'm not criticizing, I'm trying to learn. Thanks!

@artbyrobot1 4 года назад

was thinking the same thing but don't think the capacitor is needed as that is already in the inverter. Just a inductor in series would be needed I think?

@Nic7320 4 года назад

@@artbyrobot1 -- Sure, in theory it can work, but do some math and you'll find the inductor would be very large and very heavy. And then you'll have another problem unloading the inductive current fly back when you turn the MPPT DC off, and if you don't add a big diode to catch it you'll destroy other parts.

@cxmmax4265 4 года назад

softstarter can be find in high end inverter, but it's cool anyway to see how to fix that

@hydro_johnny 4 года назад

@Rocky Robinson Because a capacitor this size probably costs more than this simple contraption and the inrush of that capacitor would be gigantic if ever discharged

@cxmmax4265 4 года назад

@Rocky Robinson it should work but you need an capacitor wich has no polarity, so if you attach a bigger load it wont work anymore, cause those capacxitor have a small capacity

@AmplifierWorld 4 года назад

It was fantastic journey of 10 minute 31 second with you. keep it up and regards from India

@herrrrr1 4 года назад

Finally a new video, couldn't wait anymore!

@prashikkhare14 4 года назад

You have completed 1.1 m subscriber still not uploaded the drone video

@greatscottlab 4 года назад

Maybe next year, or the year after that. Not sure.

@SuperSilver301 4 года назад

The quadcopter one

@Cinemaaereo 4 года назад

@@greatscottlab Maybe at the Linux's year. Right? :)

@KangJangkrik 4 года назад

@@greatscottlab Seems like u need a drink for a while

@anycatdessai 4 года назад

Don't ask him about the drone project. He doesn't like to be hurried. Let it complete fully.

@yangyan6645 4 года назад

Will an inductor in serial also solve the problem? An inductor will reduce the current surge.

@teardowndan5364 4 года назад

The problem with limiting inrush current using inductors at low frequencies (DC in this case) is that inductor values tend to be insane. Typical inductors in everyday electronics range from 100nH to 100mH but here, we'd most likely be talking 100+ henries. Also, you'd then have to deal with safely discharging all the energy now stored in the series inrush-limiting inductor when you turn off or disconnect the load, otherwise something will get destroyed by the collapsing magnetic field dumping its energy into whatever weak spots it finds.

@yangyan6645 4 года назад

@@teardowndan5364 Thank you, your explanation is very clear!

@TheRealKuif 4 года назад

@@teardowndan5364 Wait, why would we need 100+ henries exactly? A few mH would be more than enough to limit the spike somewhat. A (physically) big inductor with a low resistance would be just fine. Simply connect it in series right at the output of the DC source and stick a diode from the negative to the positive terminals to deal with the collapsing field.

@teardowndan5364 4 года назад

@@TheRealKuif Right, I must have inverted something. Tens of mH at a handful of amps is still going to be a chunky core if you want to avoid saturation and a chunky winding.

@glasser2819 4 года назад

I guess what we are dealing with here is the inrush surge current to charge the inverter capacitors, right... was thinking about zero-crossing soft-starter but this is a DC circuit, right? then use a simple car light bulb in serie with the load: will glow until current gets null ie. caps charged! Use a 3 way an "ABC Switch" to switch input between bulb then direct. 👍

@steroido9268 4 года назад

Hi Scott Great Video. You could also use a low side Mosfet to limit the inrush current. The VESC anti spark switch is doing that in a good way. So no mechanical components are required.

@MohitSharma-eu9kl 4 года назад

As always your videos really helps me ... I wanted to thank for making that wireless walkie talkie video , though your audio quality was not good .By your mistake i understood my mistake i have been doing for last 5 months in one of my commercial project.. Thanks alot scott ... Stay creative ..

@abigailgold9349 4 года назад

Pls share your update@ Mohit Sharma. Thanks aLearner Ultralead

@nicolasg3305 4 года назад

can't u put a capacitor before the inverter switch to charge the internal capacitor off the inverter just enough to prevent huge currents spikes ?

@awesomefacepalm 4 года назад

Well the current surge was caused by caps so my unqualified guess is no. It would only add another source for big current surges

@alexoja2918 4 года назад

The capacitor would then act as a problem itself. It would have to be substantially large.

@MusicBent 4 года назад

Another theoretical solution would be a series (aka shunt) inductor before the inverter. However this has two problems. 1)The inducter would create an LC circuit which may cause instability, especially with any active or switching circuits (like an inverted), and 2) many circuits would require massive inductors in proportion to the capacetence and in-rush current.

@MusicBent 4 года назад

Another way to think about it: Capacitors resist sudden changes in voltage (by creating large current draws) Inductors resist sudden changes in current (by creating large voltages).

@Cheese_1337 4 года назад

Usually inverter is connected straight to the battery.

@beedslolkuntus2070 4 года назад

Even I was thinking that!

@Nic7320 4 года назад

Agreed, but Victron smart MPPT controllers have a nice histogram feature going back 30 days that makes their switched DC output very useful diagnosing problems. My DC powered 'fridge was shutting off and I didn't know it until I discovered it on the history page.. I wish all their products, including their inverters, had this.

@beedslolkuntus2070 4 года назад

Nic Oooh

@millomweb 3 года назад

@@Nic7320 So what was the cause ? Not powered direct from battery ? ;)

@Nic7320 3 года назад

@@millomweb I'm running two refrigerators and the rest of my RV off of a 24 volt Tesla battery module. The cause of the shutdown was actually the fridge; it thinks it's supposed to shut off if the input voltage drops below 21.5 volts, which is designed for a 24V lead acid battery, but not the proper voltage cut-off for my Tesla LiIon battery. The Tesla 6S LiIon module voltage range is 25 volts down to 20 volts. I had assumed that since the fridge could run on either 24 volts or 12 volts, anything between them was okay. But it turns out the fridge has two shutdown voltages for either 12V or 24V operation. My solution was to put in a 24 to 13.5 volt DC-to-DC converter so the fridge always stays in the 12V operating mode, even if the Tesla battery goes down below 21.5 volts. Then below 20 volts, the MPPT controller is set to shut down the DC output to protect the Tesla battery. Maybe that's a long answer to your question. I do run my inverters directly from the battery, but smaller DC loads, like the fridge, I like to run off the MPPT controllers so I can see the histogram.

@anthonyvolkman2338 4 года назад

I use contactors for my "relay" due to my circuiys drawing hundreds of amps. I do like how yours is designed (almost identical to my design). Jeep up the good work Scott!

@CottonTailJoe Год назад

Your videos are very inspiring thank you.

@aswinvr1912 4 года назад

Hi GreatScott... Is it possible to remove the relay and use only the mosfet.

@alexoja2918 4 года назад

Yes, however all the current would then go through the mosfet and stress it, requiring power components and producing heat. The problem this presents is a greater one than the required relay current.

@victornpb 4 года назад

Yes

@GoodElectronics 4 года назад

It's possible, but in mosfets there is a voltage drop.

@jaa185 4 года назад

yes of course, but you need to drive mosfet tightly,say by opamp..

@psialt9720 4 года назад

Yes, but mosfet has voltage drop, and it will heat up

@johannes5219 4 года назад

Could you also put an inductor in series? Would be more inefficient I think.. :/

@caffeinatedinsanity2324 4 года назад

If you don't forget to put a freewheeling diode, maybe. But don't forget you want as little power losses as possible, and coils... Well... Have a good amount of ESR. Not to mention coils can be expensive sometimes.

@hadrast 4 года назад

What about an inductor with an appropriately sized resistor (say 2Ω) in parallel though? The inductor could be a lot smaller (as in less inductive), since the resistor would bypass it and start charging the capacitor immediately, and the inductor windings could therefore be thicker to improve efficiency. Once the inductor starts passing current, the resistor would naturally drop out of the equation. Even better, the resistor would always be there to act as a drain for the inductor and tamp out potential oscillations.

@johannes5219 4 года назад

Ah okay, I see.. tanks for your answers :-)

@innovation4u336 4 года назад

You are best teacher in the world. I always wait for your next video. Thanks man.

@greatscottlab 4 года назад

You're welcome :-)

@kirkdecker6228 4 года назад

Great video! Thanks for sharing your knowledge.

@NIKFLICK707 4 года назад

Can't we use inductor in series with appreciate value so that it will limit the inrush current and as soon as the voltage gets stable we will have no inductive reactance and hence no resistance/powerloss (except for resistance of that wire)???🤔🤔

@greatscottlab 4 года назад

That is why the inverter came with an inductor on the input. But the value would need to be very high to get decent results. That would be too expensive since the inductor needs to be able to handle a lot of current.

@NIKFLICK707 4 года назад

@@greatscottlab oooh thanks for replying 😍 😍

@tunahankaratay1523 4 года назад

@@greatscottlab Have you made calculations about coil properties? Since the pulse period is long, you could use an iron core of a ballast of a fluorescent lamp(15ms would equal to around 150 hertz in ac).

@rrp49 4 года назад

Thats why always the inverter go direct to battery and no to the charge controller xD

@artbyrobot1 4 года назад

solar systems don't need batteries as you use grid power when sun isn't out and use solar when sun is out and feed back to the grid during the sun being out which turns your meter backwards and rewinds it for a total net use of zero. Batteries then are a waste of money for home solar - unless if you don't have grid access...

@rrp49 4 года назад

@@artbyrobot1 i'm offgrid in the other case why you need inverter ? In the on grid micro inviertes just need and go direct to ac

@rrp49 4 года назад

artbyrobot but in a blackout u don't get any energy without batteries

@millomweb 3 года назад

Glad I'm not the only one to spot the deliberate mistake - LOL. It the 'load' that should go to the battery - then everything's covered.

@noweare1 3 года назад

You would still have a problem any time the inverter turned on.

@Alacritous 4 года назад

Terrific video. I learned a lot. Your videos are always informational with minimum verbosity.

@martink9785 4 года назад

We used to use 3 phase soft-starts on 130kw bore pumps. 2 pumps made one water screen. We had to turn each pump on separately so we didn't overload the supply. It was interesting to see the first kick then ramp up. The soft starts made great sounds as they worked until the bypass kicked in 🙂

@timweilacher6457 4 года назад

And next time a AC soft start pls😛

@glasser2819 4 года назад

you can just buy full featured soft-starters from Schneider with a bullet proof "alternistor" (dedicated triac) for the price of parts alone... 😊

@nemoskull2262 3 года назад

@@glasser2819 link?

@timweilacher6457 3 года назад

@@glasser2819 Diy or buy? Would be fun to know how these things work.

@id15807936 4 года назад

Wouldn't it be better to just use a MOSFET to bypass the resistor instead of using a relay ?

@cattflap1447 4 года назад

+1 I thought that too, is there a reason why you can't do that ?

@1Hippo 4 года назад

Yeah thought the same, maybe because the resistance of a closed relay is lower than a FET, which has still a low RDSon? But with his low current (

@marksawyer6242 4 года назад

You could implement something simple with a P-Channel MOSFET but the Rds ON is relatively high, probably similar to a relay, or maybe worse than a relay. If you want minimum losses, you would need an N-Channel MOSFET, but that increases the complexity because you need a Gate drive voltage which exceeds your Source voltage by around 10 or 12 volts typically. That would require a charge pump circuit to generate the required drive voltage. That's a lot of extra components. As with everything in electronics, it's always a trade off between cost, efficiency, reliability, space, development time. Did I forget anything?

@id15807936 4 года назад

@@marksawyer6242 How is it even a problem to get 12v to drive a mosfet if there is a 12v source in this circuit? and yeah i meant N-channel mosfet being connected between the load and the minus of power source

@marksawyer6242 4 года назад

@@id15807936 You could theoretically do as you say and implement the inrush current limiting circuitry on the negative line to make it easier to drive the N-Channel MOSFET. However, i would never recommend it. Messing with your return path is generally bad practice. Consider what happens to the system when the inrush current goes through your resistor (before the MOSFET has switched on) the return line of your entire system will be at an elevated voltage, due to the potential created across the resistor when the inrush current goes through it. Then your MOSFET would switch on, and suddenly the entire system jumps back down. That may be ok if you are operating your system in isolation. But consider the effect that could have if you have multiple electronic systems connected together, and one of them shifts its return potential level relative to the other systems. If your computer PSU did that every time you switched your computer on it could easily cause damage to the peripherals that were plugged into it, due to potential differences creating ground loops.

@Zebra_Paw 2 года назад

I needed this for my new gaming audio setup, not because of the inrush but because it makes a huge noise in the speaker.

@jayjames5839 4 года назад

As usual a great presentation & explanation 👍

@tunnelsnake627 4 года назад

6:30 great Scott has Germanys final solution.

@speedsterh 4 года назад

Give the germans a break ! It must be tiresome for people like Scott to be constantly reminded of WWII

@mannyquinn9031 4 года назад

Won't an inductor work as well as a resistor on the input to reduce inrush current ? ...nice video m8 keep it up

@hummer515 4 года назад

I don't think so because the inductance of an inductor must be established first. So the inductor would only have a small resistance in the beginning and would not cut off the high currents.

@mannyquinn9031 4 года назад

Corn the inductance are used to reduce the inrush current since the rise / fall time is very low ..it should have a voltage drop across ...correct me if I'm wrong :)

@MrCh0o 4 года назад

Maybe it's to prevent oscillations caused by both capacitor and inductor? That would be my guess After some further reading, nope, seems like this is indeed the way to go :')

@frodev728 4 года назад

Wow I’m so happy to see this video! I have the 100|20 MPPT from victron and have the same issue when plugging in my 12v compressor fridge and 12v macbook charger...

@SGRAHMD 4 года назад

awesome video thanks for showing the experience dude!

@elninorosario 4 года назад

Can we just switch on that switch based on the voltage of the capacitor? .. (using a comparator maybe) .. and avoiding the delay circuit entirely!

@tunahankaratay1523 4 года назад

Surely, but it is a bit less convinient imo.

@elninorosario 4 года назад

@@tunahankaratay1523 or maybe just a constant current source using a mosfet?

@tunahankaratay1523 4 года назад

@@elninorosario Aww, that one would probably be problematic. It works like a very high frequency oscillator so it is not pure dc. You would need to smooth the current with an inductor but then you could also directly use an inductor. The inductor size will decrase with the circuit of course but it would still be very bulky and expensive. Relay circuits are even more efficient with big loads and it is super cheap and simple too.

@tunahankaratay1523 4 года назад

I think I need to clarify a bit more. The constant current circuit is a comparator with variable voltage input on one side and a current sensing resistor connected on the other input. The resistor connects to ground and the load. Since the mosfet gate has a capacitance in the picofarad range, the circuit acts like an RC oscillator. This oscillation is a square wave with changing duty cycle and frequency. It works at the end but the voltage isn't perfect dc. And the mosfet would waste more power than 0.5w(0.05 ohm*10 amp=5w, crazy)(the relay res is as negligible as the wire res).