Just purchased a soft starter for a 3kW toroid transformer, doesn't work.

[George5]

Hi!
This is my very 1st posting on this forum.

Just recently purchased a home made soft starter for my 3kW toroid transformer over the internet and it doesn't work.

What seems to be the problem is that the triac never kicks in to take over the conducting of current from the power resistors.
As the seconds or minutes pass by the resistors get warmer and warmer while the triac stays on room temp.
The household appliance (food processor) that's connected to the toroid won't even move if it's loaded with veggies, it does spin if I leave it empty but I can sense that there is no real power behind it.

Btw.,  my toroid is a 3kW one not because I have a near 3kW powerful appliance to work with but because when I needed a 2kW transformer, I couldn't found any, so I purchased this one. But the max. load that I put on the toroid 5-10 seconds AFTER I turned the toroid on is not bigger than 1800 Watt one.

I needed a soft starter solely just to start the toroid because 1 out of 5 times it triggered the circuit breaker of our apartment.

(I'm using the toroid to get 120V for several of our household appliances that I brought home with me when I moved back to Hungary from the US.)

But going back to the subject of the soft starter, the guy, who sold me the unit over the net isn't too friendly, and not willing to go through some troubleshooting with me .

Today I posted a similar message on a similar forum in Hungary and I got several answers but I'm not sure if I got the right answer from there since nobody seemed to be strong on triac based soft starters (no relay).

I was told that the soft starter that I posted pictures of on that forum shouldn't even work, it's a bad design. (while the guy who made it  and sold it to me told me that he is an electronic engineer, that I have no way of verifying. )

Someone on that forum created a circuit diagram based on the pictures of the PCB and the empty PCB drawing that I did in Paintshop Pro and then suggested 3 mods that would make that circuit work.

So, I thought I'd post the circuit diagram and the suggested mods here and ask for your opinion: whether this soft starter as it was designed shouldn't work indeed and the mods would make it work indeed?

The URL link to the pictures: https://tinyurl.com/o659qs7

Now, normally it is not my habit of posting question about someone else's opinion on a different forum, I decided to that in this case because I'm in a situation where couple of forum members stated that the circuit that I just bought from an electronic engineer shouldn't even work and at this stage I'm still not convinced that I was dealing with a crook.

George

 

[radardoug]

Theres a much better and simpler method. Get a 500 watt lamp and a 240 volt ac relay. Wire the lamp in series between the mains and the load. Put the coil of the relay across the load. Put the open contacts of the relay across the lamp.
When the mains is turned on  the lamp will limit inrush to the toroid. As the voltage builds up the relay will operate, shorting out the lamp. By the way, this would indicate that your 3 kW toroid is of poor quality. You should be able to connect it to the mains with no problem. Then plug in your 115v loads.

 

[JohnRoberts]

I am reluctant to encourage inexperienced posters to experiment with mains voltage circuits.

The "does not work" schematic, looks like it would always be on, suggesting maybe a bad solder connection or bad part.

Again be very careful working with hazardous voltages.

JR

 

[shabtek]

It is normal to trip breaker a few times before it "holds" with big toroid (at least that is case with equitech).
I'd replace breaker if it is old and leave it on.

 

[moamps]

The second schematic doesn't work either.
The simplest solution (if you don't really need automatic switching)  is using two power switches; the first connects the transformer via power resistors to the mains, the second switch is used for shorting power resistors.

 

[PRR]

I do not like either schematic.

The lamp-relay scheme is tricky; and having been bit by relay tricks before, I reserve opinion.

The 2-switch scheme is funky and awkward but the theory is clear.

The PEAK power in the resistor may be quite large, thousands of Watts. Although the surge should be short, this suggests a 200 Watt rating on the resistor or the quick intense heat will break it apart.

Have you contacted the blender factory? This is the type of appliance which *may* have two coils which can be wired parallel 120 or series 240V. (However if it is a universal (AC/DC) motor it has so many coils that only an expert could reconfigure it without much risk of blow-up.)

 

[George5]

Thank you guys for taking your time for replying my question, let me answer them in order.

Radardoug:
Although you didn't  give me feedback on the circuit in question, basically I like your idea because continuous light would indicate it right away that something is wrong with the relay circuit.

Let me share a feature related to this idea which isn't the product of my brain but someone else's on the net: Using two bulbs instead of one (for e.g. 2 x 250 W bulbs) would load each bulb with only half of the voltage it was designed to run on and that would extend the life of the bulbs to eternity. He actually suggested two 25W halogen bulbs but it could have been for a smaller soft starter circuit, I didn't read the whole article.

Wouldn't it be a good idea to use a push button momentary switch instead of an  on/off one, so that you have to push the button until the light of the bulb goes off meaning that the relay has taken over, but in case of a power outage the toroid and the appliance wouldn't be subjected to multiple surges, you would have to push the button again to turn them on?

I'm not the person to tell whether the 3kW toroid autotransformer that I need the soft starter for is a good or a bad quality since I have nothing to compare it to.

This is my first and probably the last toroid transformer that I'll own in my life, it was made by Trakis, a Hungarian company in 1973 and I'm sure of that the factory has strongly recommended using a soft starter with the unit or a minimum sized fuse or circuit breaker in the wiring of the shop where it was to be used. I don't think they even considered that this 3kW transformer will be used in a residential home in Hungary back in the seventies.

Here you can see a few pictures of the unit:
(these pictures were taken by the guy who I bought the unit from, so for e.g the connection panel has already been replaced since then.)
http://pumi.org/geza/temp/browseable/3kw-trakis-toroid/


JohnRoberts:
I just clicked on "I read it" but I haven't really read the user's agreement of the GroupDIY website but I'm sure it should have a legal statement in it stating that this website is not responsible for any harm or damage in personal health or other property by following advices made my forum members not depending on whether they are technically correct or faulty, and each forum member bears full responsibility for deciding whether he or she has the knowledge or experience to follow any given advice read on this forum.

And this message should be there to protect the website as well and its members against any potential lawsuits in case an accident does happen. So, you, as an individual member shouldn't feel the urge to find out about each member's expertise in electricity you communicate with BEFORE giving out any advice that deals with higher than 50V.

Personally, I'm a 56 year old fellow with 13 years of auto mechanic, and 20 years of IT background, so I do know exactly how not use any of my body parts to test whether a 240V device is properly grounded or isn't.
If I find a solution is over my head, I either ask someone to do it for me or I just go out and buy it instead of attempting to build it. It depends on the situation. So far the "buying" version hasn't really worked out for me in a long run.

Shabtek:
I cannot leave the toroid transformer on 24/7 because it sits behind my desk in the living room and emits a not too loud humming sound but it is loud enough to bother us when all media devices are turned off. (and that is the case in my home most of the time.)  Also, several days could go by without using any high power, 120 V device, so it would be also wasting our money in utility bills.

moamps:
I like the simplicity of the idea, but I like the bulb version better because in case a series of outages happen, the switch would remain on and the toroid transformer would have a hard time dealing with the rapid outages.

PRR:
Why don't you like either schematics? Especially the "non working one"?
Why is the lamp-relay scheme is tricky?

I haven't contacted the manufacturer of any of my 120V appliances because I have like six of them and I'm sure I couldn't convert all of them to 230V.

I HAVE contacted Dyson about our pet-vacuum cleaner since I burned the motor of it down when I plugged it in a 230V outlet of a Chinese made auto transformer with identical jacks for for both the 230V and the 120V.
I asked them if I could order a 230V version of the same motor in my vacuum cleaner and they refused any info that wasn't related to ordering an original replacement motor.

 

[JohnRoberts]

Thank you guys for taking your time for replying my question, let me answer them in order.


JohnRoberts:
I just clicked on "I read it" but I haven't really read the user's agreement of the GroupDIY website but I'm sure it should have a legal statement in it stating that this website is not responsible for any harm or damage in personal health or other property by following advices made my forum members not depending on whether they are technically correct or faulty, and each forum member bears full responsibility for deciding whether he or she has the knowledge or experience to follow any given advice read on this forum.

And this message should be there to protect the website as well and its members against any potential lawsuits in case an accident does happen. So, you, as an individual member shouldn't feel the urge to find out about each member's expertise in electricity you communicate with BEFORE giving out any advice that deals with higher than 50V.

Personally, I'm a 56 year old fellow with 13 years of auto mechanic, and 20 years of IT background, so I do know exactly how not use any of my body parts to test whether a 240V device is properly grounded or isn't.
If I find a solution is over my head, I either ask someone to do it for me or I just go out and buy it instead of attempting to build it. It depends on the situation. So far the "buying" version hasn't really worked out for me in a long run.

I am less concerned about being sued, and reluctant to encourage posters to dive into possibly hazardous situations.

Very often it is experienced technicians or engineers who get hurt because they are too casual about mains voltages.

Good luck and be careful.

JR

 

[George5]

I know, that you mean well, but a 10 component circuit isn't a big deal, I have repaired PSUs of many computers and servers (if and when I could), replaced blown caps in LCD TVs, etc.. The Net with Google is my college, Youtube videos provide me with the hands on or hard to get stuff and forums like this complete my 100% no cost college education. (if and when I get an answer.)

Cheers,
George