Step down 50 volts

[Leo Voisine]

I need to take our line voltage of 240-250 or whatever it is and step it down by 50 volts. Internet search tells me that voltage in the USA can be from 216 to 264 volts.

The machine currently has a step down transformer 220v to 110v. So, if my incoming voltage is 250 or so the reduction in voltage would be 50% or 125 out. What I measured was 130v out
This step down transformer has 4 output connections - one for each stepper driver. I believe it is a toroidal transformer. Not sure, but I think that the windings are 4 individual windings to make up the 4 outputs. One hot and one neutral for 8 connections. This is rated at 2000va

The problem is - The stepper drivers require 60-110 volts.

I cannot find such a transformer to get me inside the 60-110 volts for the stepper drivers

I think I can add in a transformer BEFORE that 50% transformer to take the 250 volts and reduce that be 50 volts as long as the 2000va is met. I now only need 1 input source - 2 hots and 1 output source - 2 hots. By cutting 50 volts my output voltage would range from 214 - 190. After the 50% transformer I would have between 95 - 107 volts going into the stepper drivers which is perfect.

I know it's all about the windings.

Does this make any sense? Any reasonable suggestions

NO - the stepper drivers cannot handle the voltage. It just cost my client over $1000 for the new stepper drivers.

I can post a picture I drew.

 

[Darren Wright]

Certainly a @Steve Southwood or @Charles Lent Level of question. I just don't have the expertise on higher voltage reduction and what would be a good bet.

 

[Steve Southwood]

Hmmm, need to read this over a few times.

 

[Charles Lent]

Have I missed something? Darren's response is the first post that I see on this. Then a reply by Steve Southwood.

I'm willing to help, but don't know the question. What about 50 volts?

Charley

 

[Leo Voisine]

Is my first post not showing?

OR

Am I just not making sense?

 

[Brent Dowell]

The post is there, I see it. Don't understand it one bit, but I can see it.

 

[Leo Voisine]

OK - I will start with the problem that needs to be solved.

My client/friend has a CNC router that I help him with. On his machine that we bought from China in 2017 has blown all 4 stepper motor drivers. We replaced all 4 of the stepper motor drivers and all is well, machine is operating. But WHY did the stepper motors drivers fail?

I also have a CNC router made in China that is from 2015. My machine is almost the same as his machine so we could do testing between the 2 machines. I have the same stepper motor drivers in my machine. YAKO 2811 MA stepper motor drivers. My machine has not had any issue.

So in trying to find the reason for failure I measured input voltage going into the stepper motor drivers ------ On my machine it is about 93 volts AC ----- On Ted's machine is is about 130 volts AC

The input requirement on the Yako 2811 MA is 60 - 110 Volts ac

PROBLEM is ------ the Stepper motor drivers in Ted's machine is being over powered.

How do I reduce the voltage in order to get the input voltage within the required range of 60-110 volts on Ted's machine,

 

[Leo Voisine]

I am a mechanical engineer and I know a LITTLE about electrical stuff. A little means - enough to get into trouble.

I am not afraid to try almost anything and to learn more.

I am not well versed in the technical jargon, so the words I use to try to explain the issue may be the wrong words.
One thing I do know. The stepper drivers are getting too much voltage.

 

[Don Baer]

Leo, in the original post you mentioned the stepdown transformer that has "step down transformer has 4 output connections - one for each stepper driver. I believe it is a toroidal transformer. Not sure, but I think that the windings are 4 individual windings to make up the 4 outputs. One hot and one neutral for 8 connections. This is rated at 2000va" can you provide a picture of the transformer. Most transformers have a connection diagram on them for different wiring so also if one exists provide a picture of this diagram. If the voltage is that high it sounds like you are using the wrong "taps" on the transformer but without more info it is impossible to tell.

 

[Leo Voisine]

Don, The next time I get to Ted's shop I can grab a pic, but I am 100% that will not help. I may have a pic of it on my computer and I will post it later today if I have one. Ted's shop is a little over a one hour trip. It is a toroidal transformer and the ONLY outputs are the ones for the 110 v output. There is NO wiring diagram and there are NO other connections (taps). I completely understand what you are saying. Also - there is NO adjustment screw to adjust the output. It is a dedicated 50% stepdown toroidal transformer.

 

[Don Baer]

well then if you just need to reduce the output voltage you can get a Buck/Boost transformer. you can take 250 and reduce it to say 208. They come in various sizes and ratings. Here is a link.

https://www.larsonelectronics.com/product/223233/1-phase-buck-boost-step-down-transformer-240v-primary-220v-secondary-16-06-amps-50-60hz?utm_campaign=1973742206&utm_source=google&utm_medium=cpc&utm_content=353358798473&keyword=&adgroupid=70114088839&gad_source=1&gad_campaignid=1973742206&gbraid=0AAAAAD_IdMwqNbEAFHfTRkHvwr4ZTk4eJ&gclid=Cj0KCQjw7cLOBhDmARIsAGsuA0nBwvXI_Vnx-bJ36QCfewJraVXcB8MO5zWH279e2BI7YwAwpR9IkMIaAvytEALw_wcB

 

[Leo Voisine]

Yes, I have been there and looked at that already, I have a new quote from Larson, but depending on the variation of voltage coming in from the electric grid I end up with either MAX or overpowering the stepper drivers. I also do not want change whatever else is the control cabinet. That buck from Larson only reduces the voltage by 32 volts. It is 240 to 208 volts. This does not look like a best decision, but it is a better than nothing option.

I am wanting to reduce only the stepper motor drivers voltage. I want something to reduce the voltage before the 50% transformer by about 50 volts. This way the ONLY the stepper drivers are on that circuit and that would ensure the stepper drivers the voltage within the required range.

The other option would be to find a new 50% transformer to be a higher percentage step down.

I also had Larson give me a quote on a replacement transformer but it only has one output, and it is almost $1000.

 

[John Bartley]

If I read you right, you would ideally like to reduce your 260vac (as it is currently) line voltage to 240vac so that you 2:1 built in power supply will have the correct output?

NOT an expert here, but is it possible that what you're looking for is a "Bucking Transformer"? They are designed to lower or raise line voltages in the way you want. I think companies like Hammond Transformers might be able to help and they sell thru' companies like Mouser Electronics and others.

This article may help with more tech info? : https://sound-au.com/articles/buck-xfmr.htm

 

[Leo Voisine]

To some degree yes, in the sense that I need to be reducing line voltage down to the voltage I need for the stepper drivers.

I am completely certain that I am not describing what I am trying to do well - because I don't know the terminology well enough.

As I go through this process and dig deeper I learn more.

Today is Easter so between church and family it is a busy day. I will try again to draw a new diagram tomorrow to make an attempt to describe it better.

for now - gotta go

 

[Leo Voisine]

If I read you right, you would ideally like to reduce your 260vac (as it is currently) line voltage to 240vac so that you 2:1 built in power supply will have the correct output?

YES - but I want to step down by 50 volts
This is ONE scenerio

The other scenerio is to eliminate the 2:1 and step down line to 95v with 4 taps

 

[Steve Southwood]

Try running your issue through an AI platform when you get the chance.

Personally I want to know why you have 260V. That's way out of range for around here.

 

[Brent Dowell]

Try running your issue through an AI platform when you get the chance.

Personally I want to know why you have 260V. That's way out of range for around here.

That does seem to be kind of the big question here. Seems like it would be causing other problems as well.

 

[John Bartley]

I think the first thing I'd do it take measurements of your supply voltage wherever the machine is going to be plugged in "as built". Do this every hour for a day or two and record the results and average them. That's your "source voltage - SV".
Second ... your machine, as built is wired to what input voltage??? That spec'd input voltage should be your "target voltage - TV".
Third, the bucking xfrmr should reduce SV to TV at the current needed + some current allowance..

Steve has an exellent question about line voltage.

 

[Leo Voisine]

I can measure the line voltages again to be sure.

I cannot measure every hour for a couple of days. Teds shop is an hour trip from me.

I saw through a google search that US voltage can range from 216 to 264 volts.
I want to plan accordingly.
I know in my house I measure a full 250 volts

This is not a new machine, Ted bought it from China new in 2017
The 4 stepper drivers blew over several months a year or two ago.

After we determined that the drivers needed to be replaced and the new drivers were installed I wanted to find out why they failed, so I started to measure the voltages.
I will go back and remeasure the voltages, but I do know the stepper drivers are being overpowered.

Either way - there is nothing I can do about incoming voltage.

Shooting for 220v at the 2:1 transformer puts the steppers at a MAX input voltage of 110v and I want to see a "safety" voltage of around 80-90 volts going into the stepper drivers.

I will go and remeasure voltages early this week.


Even so - if the incoming voltage is 240 +/- 5% - then the voltage range will be 252 - 228.
Then going thru the 2:1 transformer I will get 114-126 in for the stepper drivers.
The stepper drivers input requirement is 60-110 V ac input.
That is still overpowering the stepper drivers.

I prefer to be midrange of the stepper motor drivers and never overpower, hence why I am shooting for 80-90 input for the stepper drivers,
I want to regulate the voltage to the stepper drivers only.

I don't want to change voltage going to the spindle or VFD for the spindle, so a buck transformer is not my first choice.

 

[Leo Voisine]

As I go through this process and read the manuals and research online I am learning more and more. I also found out WHY the VA on Teds machine for the 2:1 transformer is rated at 2000.

I believe the Chinese buy the 2:1 transformers in volume and just adjust the stepper drivers output to match the VA of the transformer. As I was looking at transformers on Alibaba I could see the transformer Ted has. They have volume pricing. They CAN make the 2:1 transformer Ted has, with the requirements I want 250-95 volts, but qty of 1 is $1000 plus shipping

The setting for amperage out from Teds stepper driver is set to 4.5 amps, which when calculated out equals 2000va at 110v. The stepper motors are rated for 6 amps. I think Ted is only getting about 2/3 of the power he could get. Overall if I got a stepdown transformer to provide the 6 amps at 95 volts the va would be about 2280 VA

What would be the danger in this.