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- เผยแพร่เมื่อ 2 มิ.ย. 2024
- DIY Soft Starter Circuits (Inrush Current Limiter) for AC and DC Loads
Inrush current/Switch-ON surge is the maximal instantaneous input current drawn by an electrical device when first turned on. Inrush current is much higher than the load’s steady-state current and that’s the source of many problems such as fuse blowing up, load failure, load’s lifetime reduction, sparks at the switch contacts … etc. In this design, I have introduced two inrush current limiter (soft starter) circuits for both AC and DC loads.
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Article: www.pcbway.com/blog/technolog...
Check other videos: bit.ly/2N9OlPa
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#soft_starter
#inrush_current_limiter
Inspired by:
GreatScott!
How to make a Softstarter and why it is sometimes mandatory to use!
URL: • How to make a Softstar...
Inspired by:
electronicsNmore
URL: • Simple/Effective Solut...
Inspired by:
Kasyan TV
This device will extend the life of your home appliances!
URL: • This device will exten... - วิทยาศาสตร์และเทคโนโลยี
Inrush Current Limiter (Soft Starter) for AC and DC Loads
This a complicated low tech resistive solution.
Use a cheape NTC resistor with no need for any PCB
or a smart starter with NO Resistor
@@glasser2819 PTC/NTC does not work like this. It reacts slowly and it does not recover fast, besides it only works with the currents that are "much" higher than steady state.
NTC under load can also reach high temperatures as high as 120deg C depending on the type.
Nice tutorial man 👌👌
Thank you 🙌
Brilliant Explanation Sir 🙏🙏
Thanks for liking it, your name "Shankar" reminded me of an Indian movie, named "Koyla"
After long time
I really like your job and the proper documentation!
Please allow a question for a dummy like me :)
Is this suitable for a Sunkko 737G battery spot welder, having 50-60A inrush current when turning on? It activates my mains circuit breaker (20A) frequently, hence I'm looking for a solution. During the welding I measured 15-20A inrush only, for a very short time, it never trips my breaker during welding, just when turned on.
Is there any modification recommended (more powerful relay, thicker wires?). Thanks for replying. 👍
No problem, You're welcome.
The inrush current should not be and it is not normal. it is like you start your car with pressing the gas pedal till the bottom. Therefore yes it can be fixed and this circuit can help you yes.
The relay on this PCB ranked for 10A, so you need to replace the relay with a more powerful one, but identical voltage. if your continuous current consumption is around 15A to 20A, then for example a 12V-30A relay is okay. the 3.3R-5W resistor is the default value. You can modify it if you like, however, I suggest to buy several resistors and check which suits you best. Also, change it to 10W. for example buy these: 2.2R-10W, 3.3R-10W, 5.6R-10W.
I assumed the load works with 12V and used a 12V relay. if your load voltage is different, you need to slightly change the circuit. as a result, for your case the PCB and schematic (if your load voltage is not 12V) should be modified, however the circuit base is identical.
I have created some uncovered areas on the current-carrying tracks on the PCB if the user decided to strengthen them by think copper wires or soldering.
I explained all details if you are gonna do it yourself, however, if you still had some problems, just contact me by Email to design another circuit for you as a project contract.
Hi, i'm new in electronic design and have a question. I want to build it for dc circuit 48-50v and 20A, and based on your video's it show for 12v. Any suggestions what i need to change for my application? Sorry for basic question. Thanks!
Yeah, I was be able to design it better with the separate 12V supply connector just for the board, however it is simple, you should be able to modify it and redesign it for your own purpose
This is a fantastic job and explanation, you made it cheap and easy way, thank you, I have mitre saw 1800w and use maximum 15A do I need to change the relay and resistor? What size resistor do I need please?
Thank you. Glad you liked it.
Yes, you must change the relay. higher than 10A is industrial, the circuit should be changed, however, concept is identical, but it is better to change the circuit. Power resistor should be more powerful, yes
@@MyVanitar thanks for your reply, what size power resistor ? Also can you add like for industrial relay please
I was looking for the same solution. I have a mitre saw and a table saw which both see an inrush current in excess of 30A for a fraction of a second before settling down to around 9A without the additional load from cutting wood.
Please would you make a video or a web page explaining what changes are needed to the circuit and it's components for a power tool soft starter.
Beautiful design. But even as an experienced amateur electronics engineer you usually have no possibility to produce PCB using Gerber files for PCB fabrications.
Is the board available for purchase somewhere? Elektor?
Thanks, Check the article. As I mentioned in the video, you can find more details about the design and also the place to order/download the Gerbers
thanks for the video. can I use your ac soft starter circuit for my refrigerator and washing mashine?
No, the compressor of the refrigerator needs a moderate rush current at the start point. by the way, even my own is a big two doors refrigerator and I have no problem. please check for malfunction or current leaking. that might be the reason.
Hey, nice work! I'm learning from your replies too. I'm wondering if it works for compressors that need extra force to start, for example a 12V refrigerator.
No, older compressors (piston based) need such an inrush to start. I suggest you use devices with "inverter compressors". they are powerful and way more efficient
I have introduced another soft starter circuit on the channel also.
Hi newbie to electronics so bare with me still learning....
Purchased the AC & DC pcbs from pcbway.
On the DC soft starter I don't seem to get any power from the negative output until I short it with the negative input to drive a 12v pc fan for example.
Also can't under stand the common ground on the PCB. I would of expected a negative rail for the common ground or some sort of link back to negative.
Thanks again for videos.
No problem Matt, everyone was a beginner one day. for the DC soft starter, it is just a simple delay circuit and a relay. Ground is shared between input and output (check the schematic). As you see, the SW should be connected to a switch, that activates the soft starter each time you decide to turn on your load.
@@MyVanitar many thanks for reply...understand the switch and the overall concept but when I put the tester on I don't get any connection with the negative output to Q1 ground for example, even the capacitor negative .... its like the pcb hasn't got a ground layer ? or am I still missing something in DC circuits. AC pcb works great. just wondered if you had your negative output connected to anything else in the video before gets to the motor etc...cut off at the bottom of the screen.
oh yes, now I got what you mean. Yes, it seems the ground path is missing. I really amaze why this thing happened because it is fine with my own PCB which is clear on the pictures and tests.
By the way you can fix it manually by soldering some wires between ground pins and tie them together (they are 5 Pins). AC soft starter is fine. I've not being noticed since most user build the AC one. I will update the Gerber soon.
ok great thanks again for reply and keep up the good work.
Can circuit like this be used in solar power wall to protect the BMS? 60v battery with charge/discharge at 20amps.
in general yes, the concept is the same, however, you should make some changes in the circuit
Gostei muito do circuito. Como modificar AC Soft Starter para tensão de 120V ?
you can use this one also: th-cam.com/video/_QyYtV-IEO8/w-d-xo.html
@tar Obrigado pela sua resposta rápida. Vou ter o link.
Tem um documento da Texas Instruments sobre uma fonte Hifi para amplificadores, e tem um Soft Starter na pagina 7.
Pesquise no google por: "AN-1849 An Audio Amplifier Power Supply Design (Rev. C)"
the core of the idea is similar, one high-power resistor for the startup and a Relay to short the resistor. in my second design (I gave you the link), you can adjust the delay
Sir, I am looking for a soft starter for a 19.5V dc motor. What components should I change on your pcb?
use a DC-to-DC converter to convert 19.5 to 12V for the supply of this circuit. that's it.
can we use NTC thermistor on AC loads to limit inrush current ?
it is one option, however it is slow to act and recover
Hi, I am dummy in electronics, but i appreciate your video. Can your designed Circuit for Ac current, be used for air conditioner(AC Current - Fixed speed Compressor air conditioner).
My ac is small , having 800Watts as power consumption, running at 3.5 amps, I want to operate it on solar, but the inrush surge is problem for inverter to handle, can you give your valued view for this.
Thanks 👍👍
No, an AC conditioner compressor needs an inrush current to start, otherwise it might be damaged. it the newer models, the compressor won't start until the electrical conditions are met. You can use weaker AC conditioner. Also, new conditioner models consume less energy and therefore they need lower start current request
@@MyVanitar Thanks for the reply.
Its new Ac, not old.
I just looking to run it on solar for daytime. Can you advise on it, Thank you very much for your effort. 👍
@@harpreet928 I understand your idea. This summer is so hot, many countries fell in problem, as well as the electricity providers. You said your AC is 800W, this is just its normal operation consumption which is not low. it needs more than this to start the compressor at the cranking. use thick copper wires for connections. Your AC is powerful. As I said there are many on the market. smaller ones (less powerful compressor, the compressor size is the same size of the normal refrigerator). Your inverter also is not a 100% conversion device. it has some loss naturally. its output should be pure sinewave.
Hi sir, Anything need to change if i use it for 110v?
not the circuit, but probably the value of 2-3 components
@@MyVanitar thanks for reply, I will try myself.
Hi. Limiting inrush current is just for protect device isnt it? It still pulls high current but protects device. I have no deep knowledge. Is there any chance to limit current from power outlet on start? I have a 1200w single output power supply for my lipo charger. Everytime i plug it, home's circuit breaker operated just for one time. After I open the circuit, everthing is great. It never failed while working. I think charging capacitors in power supply pulls too much current at start. I dont know. A friend told me turning on circuit breaker for one time isnt big deal but i am looking for solution. Could you help or advice?
Yes, charging capacitors eats too much current in the beginning, however, once they got charged, then you are fine for some time till they get discharged again. inrush current is not okay, it impose stress on the load and fuse. sometimes inrush current on one load, will damage other loads also, because it is like sudden decrease and increase in the mains voltage (in case of using an AC load). You can build the soft starter and see. that's cheap. In the future, I'll publish another version of the AC soft starter as well. This one can deliver up to 10A, it means 2000W maximum.
@@MyVanitar thank you for ur time. What do you think about that? Looks really simple electronics-diy.com/soft-start-for-power-supply.php
@@marcoscimbom Concept is the same, but your mentioned design is bigger. you will have some difficulties to build it because it offers no Gerber files for PCB fabrications and some component footprints are old fashioned. I think it belongs to an old publication of the Elektor magazine .Try a tested design like mine :-). if your continuous current draw is less than 2000W, just go for it. I'll publish another 6000W later on.
@@MyVanitar thank you so much. I have just saw your article. Looks really clear for beginner like me. But just asking for clarification, p1 is 220v n and l input, load is gonna be connected to supply l and n. Supply's and ur circuit's gnds are gonna be connected cord's ground right? Is supply's output voltage important? Its 1200w 220v 48v output. Sorry for stupid questions, i have never did on anything with ac. Looks dangerous to me 😬
@@marcoscimbom I partially understood. your question. there is no ground in the AC load. That ground is for the circuit, if that was what you meant. I have provided two designs, one for AC loads and another one for DC loads. in The AC soft starter, there is one input for the Mains, one for the Switch and another one for the load connection. As I understood correctly, your device works with 220V and sucks too much current in the beginning. So just use the AC soft starter and embed it inside your device. if this is your first time with AC, be careful!
what would need to change on the DC version to go from 12v to 48v (30A max load)
it's not possible with this design and PCB, if you want I can design it for you with an agreement
@@MyVanitar Sounds interesting, what kind of agreement?
Do you want something for free? it's not possible. send me an email to calculate the cost of your project
@@MyVanitar sorry, already found an off the shelf solution.
I wish you the best
An easier solution for limiting DC inrush current is using an NTC thermistor, it's widely used in industrial designs.
Some even use a resistor and bypass it with a relay after a certain time.
Nice demonstration, you didn't explain how the circuit works though...
NTC thermistor can not take fast inrush currents. That's why there are some expensive soft starters on the market. Also, NTC is slow and can not act properly when there is a Switch. It means when the load Switches frequently. About the circuit, as I mentioned in the video, I have provided more details in the video description.
What’s the point if you’re not going to discuss the schematics. That was the only reason I clicked on the video.
The point is that you are too hurry and just skip the content and expect to learn everything, especially in technical science. if you were watching this completely, I had mentioned where you can find it :-( it is just in front of you
@@MyVanitar Yeah I know... I did watch it. I was hoping you would go over the schematic in the video so I wouldn't have to go read about it on your website.
@@vusiliyK That's right, I always do this to prevent long videos. Video and article compliment each other.