Author Topic: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"  (Read 55148 times)

Offline petespaco

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #300 on: September 10, 2020, 11:50:18 PM »
The link for power supplies that you sent shows a whole range of models.
  I hope you really DID get the 48 volt 1000 watt unit.  If so, what AC input voltage are you using?
If, by chance, you are NOT using a 220/240 volt AC input, the power supply probably will not make the full 1000 watts.
You might try testing the supply itself with an appropriate load to see what it is really capable of.  (the heaters from old electric clothes driers can be very handy for this.
I agree with Mads that the server power supplies are a great power source for these induction heaters.

Pete Stanaitis
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Offline petespaco

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #301 on: September 22, 2020, 01:48:11 AM »
Melting some Cast Iron with the 2500 Watt ZVS Induction Heater:
I just put up 2 videos on the subject:
-The first one:  Making some minor changes to the 2500 watt unit and a few other preparations:
/>
-The second one:  Actually doing the experiment to see if we CAN melt ferrous materials:
/>
Pete Stanaitis
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Offline klugesmith

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #302 on: September 22, 2020, 05:42:28 PM »
Nicely produced, Pete.  Thank you.  Is your ingot mold made of graphite?

Not to go too far off track, but who knows where to find that youtube video of aluminum-pouring gone wrong?
We see two teenage boys in white lab smocks and partial PPE, opening a small front loading kiln on a workbench. 
One takes out a crucible of molten Al, about the size of yours, and pours it into what appears to be an iron mold.
A couple seconds into the pour there's a sharp pop.
Camera continues to roll as the kids deal with small pools of Al starting fires on the bench,
at least one significant droplet that landed in pocket of someones's smock, etc.
No significant injuries or permanent scars from that incident.

We can only hope that youtube has a net positive effect on safety of new generations of nerds.
Pete's productions are good.

Offline petespaco

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #303 on: September 22, 2020, 08:15:40 PM »
Quote
Nicely produced, Pete.  Thank you.  Is your ingot mold made of graphite?
Thank you for your kind words, klugesmith.  Yes, it is made of graphite.  I spend 'way too much time explaining its fabrication on the preparation video.
Regarding the aluminum going wrong:
  I didn't say it in the video, but before I did the test, I baked the sandbox and crucible for an hour in a 250°F kitchen oven, to make certain there wouldn't be ANY moisture.
  i/we have had a couple of incidents in the past that brought that issue into crystal clear view!!!
For instance:   a bit of grease left in a bearing shell reacts exactly the same way that water does.   Seeing molten babbit squirting 10 feet into the air does leave a lasting impression.  Dry, Dry Dry!!!

Pete Stanaitis
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Offline extremeodd

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #304 on: September 23, 2020, 12:35:16 AM »
Oh man this thread is a wealth of info on these various Chinese zvs induction heaters, was well worth the time it took to go through it in it's entirety. First off I just want to thank you Pete for your meticulous documentation of seemingly every last detail when doing or changing anything with these circuits. I've been to your site quite a few times while trying to learn what I can about how these work, why these work, why these like to randomly die, and how to make them work better. By far you've been my most helpful resource.

I currently have like 4-5 of the "5-12v" modules that are all the same design with slight variances in smd component sizing, one that uses a center-tapped coil (single toroid, meant for driving the included flyback transformer) that claims 12-36v input and has ifrp250n mosfets, and finally, one of the ones that is sometimes listed as "1000w" but still runs the bog-standard 2 caps/2 chokes setup with ifrp260 mosfets. Oh, almost forgot the 3.7v-4.2v unit, mostly because I've yet to find anything it has any application for due to its extremely weak performance https://www.ebay.com/itm/ZVS-Induction-Heating-Machine-Module-Low-Voltage-3-11V-4-21V-High-Frequency/292287860722.

I'm using these units mostly for heating up a "Dynavap VapCap" which is a 'flame powered' herbal vaporization device. Basically it's a stainless steel one hitter that has a cap that when heated to the correct temperature makes a loud click via a bimetallic disk, this indicates that it's ready for a drag. Normally the user would heat the end with a butane torch while constantly rotating but this leads to inconsistent performance and hotspots which can cause combustion instead of vaporization. That's where the cheap 5-12v induction heaters really shine, with a solid 12v psu it'll heat the dyna to temp in less than 10 seconds usually.

Not being one to leave well enough alone I've been trying to optimize the setup to work well on lower voltages as heating times dramatically increase once the voltage is under 12 and I'm wanting to make some portable setups that more pocket-friendly than 4 18650s allow. Most of my focus has been on flux control/concentration, stainless is a fairly poor metal for magnitism and I figured focusing any stray flux could be very beneficial. With that said, if finding solid info on the how/why of the chinese zvs induction heaters is tedious, finding anything about flux control in induction heating is just painful.

Theres a company that produces a putty of sorts that you cover the outside of the with and it concentrates the flux in the center of the coil (or on the inside of the coil if it's doing bore heating, on one side of a flat coil, etc) The companies site can be found here https://fluxtrol.com/magnetic-flux-control-in-induction-installations . Sadly I haven't found much in the way of disccusion on the topic anywhere on the internet and it doesn't appear the average person can buy it directly from the company.

The other "technique" I came across with some actual discussion, albeit it's posts from a single guy, using a ferrite U core with a corner broken off to create an intensely focused spot of heating. Basically, the U core goes through the work coil and the work piece is placed in the core's gap. He was using it to solder copper joints super cleanly with no visible color changing/torch damage. It appeared to work impressively well and I've had some limited success trying to use it for my purposes. If you want to try it yourself just take a ferrite core and clamp it with the one leg inside the work coil and a piece of metal (I use razor blades) pinched in the other leg. With 12v and about a 4ish amp load it'll almost instantly make the area that is in contact with the ferrite red hot, this could have applications for blade heat treatment imo.

Otherwise, my time with these devices has been mostly spent trying to fully grasp their operation and what causes them to randomly die. I've had 3 of the 5-12v units fail with no obvious signs of why or what failed and I managed to kill the centertapped work coil unit by using it to load test a 12v 30a psu I modified to be adjustable to ~20v. It simply stopped drawing current when I got up to about 12a@18v, I'm assuming one or both of the ifrp250n mosfets blew. Looked into replacing them and it's honestly not worth the trouble considering I can get another for $18 that also includes a DST flyback transformer.

Figured I'd try to contribute what little I've gleaned that I didn't see come up in the thread yet.

PS: Here's a quick tip for when you copy ebay/amazon/whatever URLs to share: You only need to copy up to the "?", everything from the "?" on are user data parameters that only serve to make the link excruciatingly long. (Also they are used for tracking where the person came from, amazon uses it for commission on affiliate links) For amazon the cutoff spot is "ref=pd", you only need the stuff before that for the link to work.
For instance:
https://www.amazon.com/SainSmart-Voltage-Switching-Generator-Ignition/dp/B00ZTTVX4O/ref=pd_bxgy_img_2/140-7389242-9697844?_encoding=UTF8&pd_rd_i=B00ZTTVX4O&pd_rd_r=e7161629-c58e-48bd-ba5a-87f0877b1b5a&pd_rd_w=QDj6G&pd_rd_wg=NjoIX&pf_rd_p=ce6c479b-ef53-49a6-845b-bbbf35c28dd3&pf_rd_r=JSFD7Y9DMKQYSXXED3MC&psc=1&refRID=JSFD7Y9DMKQYSXXED3MC

Turns into

https://www.amazon.com/SainSmart-Voltage-Switching-Generator-Ignition/dp/B00ZTTVX4O/

Or
https://www.ebay.com/itm/Digital-LC100-A-LCD-High-Precision-Inductance-Capacitance-L-C-Meter-Tester/123977420869?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D225086%26meid%3D8c6a5bce9c874c0f83bed2e2a2b03f4f%26pid%3D100675%26rk%3D3%26rkt%3D15%26mehot%3Dnone%26sd%3D292287860722%26itm%3D123977420869%26pmt%3D0%26noa%3D1%26pg%3D2380057&_trksid=p2380057.c100675.m4236&_trkparms=pageci%3Aac9eeaf5-fd23-11ea-87c6-2eff4665e3f4%7Cparentrq%3Ab7f388d81740aadcf4cf25a4fff40952%7Ciid%3A1

Turns into

https://www.ebay.com/itm/Digital-LC100-A-LCD-High-Precision-Inductance-Capacitance-L-C-Meter-Tester/123977420869

Offline petespaco

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #305 on: October 31, 2020, 03:43:55 PM »
Controlling the power to the work with a DC to DC Solid State Relay:
  Several people have asked about controlling the power to the work for these ZVS Induction Heaters.   Some ask about using frequency change to do it, others would control the input voltage to the board.    Sometimes, particularly when heating ferrous materials, the work demands wide variations of power as it initially heats up and then passes the curie point.
  Most of us don't have DC power supplies in the 48 volt, 50 amp range that are voltage-controllable from about 24 to 48 volts, so that's not an option.
So I am presently working to handle this power control by doing two things:
1. Inserting a DC to DC solid state relay into the DC line to the ZVS heater so I can use a thermocouple to sense temperature, and then control power with a PID controller
2. Using a simple meachanical "Jack" to adjust the position of the work within the work coil to keep the ZVS heater board's power consumption within safe limits.
  It the two videos that I link here, I show my progress to date.   Just recently I received my PID controller, but it was the wrong model, so I am using a simple on-off switch to control the DC to DC SSR as I watch the temperature of the work piece.

Part 1,  A cautious test of a DC to DC SSR to control my 2500 Watt ZVS Induction Heater:
/>
Part 2,  Higher power test of the SSR and using my workpiece "Jack" to control power requirements:
/>
Once I get the correct PID controller, I will install it and make an update video to demonstrate what it can do.
I will also make a short video showing the workings of a "fake" 100 amp DC to DC SSR.

Pete Stanaitis
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Offline petespaco

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #306 on: November 11, 2020, 04:29:56 PM »
I finally got my new Chinese knock-off PID controller to drive the 40 amp SSR.  In this video, I heat up some copper, just enough to draw a total of about 36 to 38 amps from the 2500 watt ZVS induction heater. ----and it works well!!!:
/>
Pete Stanaitis
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Offline petespaco

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #307 on: January 03, 2021, 07:01:15 AM »
Here's a bit of a history lesson about the range of ZVS Induction Heaters and accessories for sale on the internet.  It is intended to help makers in choosing WHAT to buy:
/>
Pete Stanaitis
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Offline Mads Barnkob

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #308 on: January 03, 2021, 09:00:09 PM »
Hi Pete, good to hear from you again and coincidently on the same day where I just for fun searched for induction heaters on ebay and saw a version that you briefly mentioned.



Have you tried this unit yet?

I am wondering if the display is just for voltage/current measurements and it nice to see that they use a huge power film capacitor now, but the small PCB tracks is too little mass for effectively cooling it :(
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Offline petespaco

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #309 on: January 04, 2021, 05:53:58 PM »
I don't know much more about that model than you do, Mads.
But here's another one, of the same general type, that has a somewhat better description:
https://www.ebay.com/itm/ZVS-3000W-High-Voltage-Induction-Heater-Module-Flyback-Driver-Heating-Board/284075222797?
It says that the display does show some status information, but I don't know what else it may show.

It is baffling to me why the Chinese continue to do such a poor job of "Selling" the Features, Advantages and Benefits of their products.
For instance, I think it would be very beneficial for them to show a picture of the display in action, and then point out the value of each piece of information.

But I DO have to give these guys credit for the level of detail about operation that they document.
I also give credit to the tech guys who do the design.  I think they are really listening to the us guys who are their potential customers.

Pete Stanaitis
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Offline petespaco

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #310 on: January 04, 2021, 06:46:37 PM »
Hello again, Mads.
Regarding the Display on the ZVS unit that you asked about:

I think the display shows:
Amps
Volts
Watts
Power On/Off
Maybe Mosfet temp
If a short occurs, which Mosfet(s?) have died.

Pete Stanaitis
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Offline hightemp1

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #311 on: January 21, 2021, 03:00:50 AM »
I know video is off-topic melting foundry and does not even use a ZVS melter, but the result is what I am still seeking using this same 2500W ZVS induction heater - jump to 5:05 in video to see the clean casting pour.

Link to graph shows copper's resistivity linear increase as temp rises all the way to liquid melting state.  A higher electrical resistance in liquid-state bodes well for clean melts - less stirring/gas pick-up, etc. for both copper and copper alloys. ----->>  https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity#/media/File:Resistivity_Cu-Ag-Au.svg

« Last Edit: February 01, 2021, 08:37:32 PM by hightemp1 »

Offline Mads Barnkob

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #312 on: January 25, 2021, 08:37:01 AM »
I know video is off-topic melting foundry and does not even use a ZVS melter, but the result is what I am still seeking using this same 2500W ZVS induction heater - jump to 5:05 in video to see final clean casting pour.

Link to graph shows copper's resistivity linear increase as temp rises all the way to liquid melting state.  A higher electrical resistance in liquid-state bodes well for clean melts - less stirring/gas pick-up, etc. for both copper and copper alloys. ----->>  https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity#/media/File:Resistivity_Cu-Ag-Au.svg

You need a crucible to get high enough temperatures. Properly also need a good amount of insulation around it and some serious water cooling to keep the work coil alive. With just 2500W you will properly see that you need to spend much longer time to get to the right temperature than with a more powerful heater.
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Offline hightemp1

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #313 on: February 08, 2021, 08:36:59 PM »
A rusky discovers the joy, trial and tribulations of melting with induction.

"I melt non-ferrous metals. Hot video. An induction heater melts copper."

Offline klugesmith

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #314 on: February 09, 2021, 06:24:13 PM »
Slightly off topic, I got a propane-fired Cast Master crucible furnace set for Christmas.  Insulation is refractory fiber blankets, and the whole thing is less powerful than one I made for backyard foundry more than 30 years ago.  No air blower, no BTUH or kW rating.

Need to whine about misuse of English technical words in many online advertisements, how-to-do-it videos, etc.

1. Too many accounts say smelting, when they mean melting metal.
It's not smelting if there is no chemical reduction of rock (ore) to metal at high temperature.

2. Too many youtube accounts refer to a crucible furnace as a foundry.  Nope, a foundry is a factory or workplace for producing metal castings.  In my experience, making good molds took more materials, equipment, and practice than melting and pouring metal.
« Last Edit: February 09, 2021, 06:30:30 PM by klugesmith »

Offline hightemp1

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Turbo Charger Add-On Board for ZVS 2.5KW Induction Furnace
« Reply #315 on: February 12, 2021, 02:55:37 AM »
Slightly off topic, I got a propane-fired Cast Master crucible furnace set for Christmas.  Insulation is refractory fiber blankets, and the whole thing is less powerful than one I made for backyard foundry more than 30 years ago.  No air blower, no BTUH or kW rating.

Need to whine about misuse of English technical words in many online advertisements, how-to-do-it videos, etc.

1. Too many accounts say smelting, when they mean melting metal.
It's not smelting if there is no chemical reduction of rock (ore) to metal at high temperature.

2. Too many youtube accounts refer to a crucible furnace as a foundry.  Nope, a foundry is a factory or workplace for producing metal castings.  In my experience, making good molds took more materials, equipment, and practice than melting and pouring metal.

Agree completely.  Chinglish -ya think someoneone would clue them in.  I ditched my 5 gallon super heavy furnace a few years ago and now really regret it.  Possibly lightness of cheap ones could be good though - less energy, although more maintenance?  Could easily soup up the burners by adding more air/gas?



To Pete & Company:
On the subject of souping things up... I think we should add a "tubo charger" (add-on mini board w fan) to the ZVS 2.5kW induction board so it can take full advantage of the 3KW power supplies everyone is using.  What says ya all?

I was reading one of Pete's older posts on adding caps and making longer coils with more turns to achieve lower frequencies (lower freq. gives deeper, faster heat penetration -not to mention safer component operation (correct me if I misread this)).  Seems industry induction furnaces are also using lower frequencies in the 5-10 khtz region, while the supplied coils that China sends us are about 5X, or 40kilohertz.  My background prevents me from whipping up a modified daughterboard schemetic.    Any thoughts from you engineers on upping up our 2500W boards to get more juice out of em, and to take full advantage of the 3kW power supplies?

No clue how to do it, but ideas so far include:
1. adding a similar sized third fan to add-on board so as to increase components/power by 50% to 3.7kW. Simply just copying/enlarging current design so this add-on board would be 1/2 the size of current board.  CRAZY 50% IDEA - Circuit board would probably explode into a million pieces and you with it  So option A is now a realistic five percent option or just pushing board without any modifications at all.
2. A full 20% boast to 3kW by modifiying current board, and future daugterboard so that freqencies are closer to industry's 10kilohertz standards .   A less expensive modification, but maybe more efficient & safer. So a turbo board/fan would be maybe 1/4th the size of the mainboard, and the mainboard would have some minor tweeking, somehow incorporated into the add-on board. 8)  Maybe this MOD could just be more CAPS and whatever necessary changes needed for more Caps?

#3 alternative - I think Pete proved that lower frequencies come at a cost = higher idle current).  If so, then maybe more than a 20%boast, say a 33% boast would be better. Though this may entail making larger traces, effect larger traces would have -- maybe a need for larger components, etc. so this may be impratical and unecomicial.  Basically, clueless here on whole turbo concept. (Correction: LOWER FREQ=LOWER IDLE CURRENT).   Still, hopefully some practical MOD for maxing out these 2.5kW boards with 3kw PS exists?

#4 alternative - 10% boast or 2.75kW - since engineers over design by this amount.  Just tweaking a few things here and there- ideas?

All brainstorming ideas welcome...

SURVEY - What Power Increase do You Vote For & How To Best Get It:

A. 50% 5% No Mods, just push current design
B. 20% Minor overhaul with turbo board
C. 33% Major Overhaul with larger "turbo board"
D. 10% Minor tweeks with smallish add-on board


UPDATE: LOOKS LIKE CHINA BEAT US TO IT - A 2500kW BOARD WITH SLIGHT MODIFICATIONS CLEARLY OPERATING AT NEARLY 3kW !  However Chinglish description warns against operating at maximum for prolonged time -Danger. So maybe we can run our 2.5kw boards at 3kw for short times and maybe 2750 all day?

https://www.ebay.com/itm/3KW-ZVS-Induction-Heating-Heater-Board-3000W-Module-with-DC-Power-Supply-Bundle/274555462249?
Looks like same board with possibly a very small daughter board for extra 12v connections. We can do better?
« Last Edit: February 20, 2021, 01:22:56 AM by hightemp1 »

Offline petespaco

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #316 on: February 12, 2021, 03:35:25 PM »
Quote
I think Pete proved that lower frequencies come at a cost = higher idle current).

I think it's just the opposite.   Lower frequencies get you LOWER idle current.

See:
https://spaco.org/Blacksmithing/ZVSInductionHeater/Work%20Coil%20Data.xlsx

By the way, "they" are now producing 4000 watt and 5000 watt versions of this basic device.

Pete Stanaitis
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Offline hightemp1

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #317 on: February 13, 2021, 06:51:01 AM »
Quote
I think Pete proved that lower frequencies come at a cost = higher idle current).

I think it's just the opposite.   Lower frequencies get you LOWER idle current.


See:
https://spaco.org/Blacksmithing/ZVSInductionHeater/Work%20Coil%20Data.xlsx

By the way, "they" are now producing 4000 watt and 5000 watt versions of this basic device.

Pete Stanaitis
---------------

Thanks for correction, Pete.   Cool, so that means we can get more power into work loads just by lowering frequency?  And lower frequencies also give us deeper, faster heating for heavier loads, like 1.5 lbs of bronze in graphite crucible.  Your thoughts on a "turbo charger" add-on board???

Another question on why amps and watts crash from about 40a and 2.2Kw to about 25 amps and 1.1kW respectively, when melting copper.  Just went back to ohms law.  So if voltage is constant from our power supplies, and amps are dropping then resitance somewhere has to be increasing.   I also found out that copper's resistivity increases linearly 20 times from room temp to melting temp with a noticeable increase at melt temp.  Can copper's twenty fold resistivity increase be the reason power crashes so much?  Some have said thinning crucibles or melted copper shorting things out, are why watts/amps plummit?  Anyone?  If copper's increased resistivity is not the answer, where is the increased resistance to blame coming from? 

Update: Resistance and Resistivity are not the same!!  So, coppers 20 fold resistivity increase is not the same as its resitance increase. Anyone kow what percent copper's resistance increases between room temp and melt temp???


Assumption:  Total power at start is 2kw, Volts 50 & 40 amps -- and at end Watts are 1kW, volts are 50 and amps are 20
 
& we know these formulas from grade school:  W=V*I  & R=V/R
 
So solving for resistance at beginning of melt and end of melt, I get (1.25ohms at start & 2.5ohms at end of melt)

I am thinking increase heat somewhere is causing the extra resistance.  Maybe the graphite's resitance is increasing and or copper's is to?

Interestingly, I just measured .25 ohms in supplied coil and .85 ohms in the crucible we are using though the crucible ohms seamed to jump around alot -could be my meter.

Math is the only absolute truth - resistance (ohms) has got to be nearly doubling!

I doubt the coils resistance is going up much so the graphite's must be going up.  But from what I've read, yes graphite resistance goes up, but does not double, maybe goes up only 40% max.  Not sure what else could be causing remaining ohmage increase.  Of course, the reason amps are dropping and ohms are rising could have nothing to do with graphite's resitance, but maybe something to do with how the ZVS circuit behaves.  But right now I think graphite's increased resistance is at least one of the culprits for power decline.  Possibly, Pete's theory about copper's resistance increasing with heat is correct and accounts for the remaining increase in amps. And the theory about a thinner crucible due to burning would also decrease power.  So maybe all three are contributing??? 

1.graphite resitance goes up with temp maybe 40%
2.Copper load resistance goes up maybe 50% with a noticable jump at melt temps.
3.graphite loss by burning is reducing power by 10%

This is all just my initial theory and may change tomorrow or in five minutes, so take it with gain of salt.  Why is induction heating so complicated?

« Last Edit: February 19, 2021, 05:43:24 PM by hightemp1 »

Offline hightemp1

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #318 on: February 18, 2021, 01:43:50 AM »
Induction Heating Manual: https://ia803006.us.archive.org/18/items/HighFrequencyInductionHeatingFrankCurtis1944McgrawHill/High%20frequency%20induction%20heating%2C%20Frank%20Curtis%2C%201944%20Mcgraw%20-%20hill.pdf
(see page 26 for schematic for a 15kw heater from 1944)


More theory & practice on blacksmithing---https://www.youtube.com/watch?v=a7W9DSpnm5E
« Last Edit: February 20, 2021, 05:07:32 AM by hightemp1 »

Offline hightemp1

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #319 on: February 19, 2021, 05:36:49 AM »
Pete's prior experiments with the 1000W ZVS heater showed, I think(?), that one could dramatically cut frequencies.  If I recall correctly, by altering the coil (more turns, wider diameter and slightly wider spacing between coils), and also by doubling capacitors, Pete was able to cut frequencies nearly 3X from approx 120 to 40KHz.  Seams like a good start to altering this board - from shallower metal surface heating for heat treating applications, to deeper heating for furnace melting of non-ferous metals.  Currently, a 1kg graphite crucible inserted into a stock coil is running at about 40KHz.  By doubling the coil's stock turns and doubling capacitor bank, hertz should be reduced to maybe 15KHz.  15Khz is much closer to where industy runs induction furnaces for melting non-ferrous metals (approx 5kHz). 

1. I counted 12 caps on the board.  Does anyone know off-hand what these caps are rated at and where to source exact or similar working substitutes? 
2. Pete used 8 gauge wire to bridge caps from main board to a 2nd board.  Not sure but I think 8 gauge should handle 50 amps on 2.5kW board so will start with that.
3. Will add 4 more turns to a coil and increase coil diameter enough so a longer silghtly wider #1.5 crucible can be used for larger melt capacity.

By doubling capacitor bank, and increasing coil turns/width I should get frequencies closer to my target.  Don't know for sure, but these two changes should not make the unit any less stable, and even possibly make it run cooler - at least the capacitors? 

As far as tweeks go regarding beefing up the board to accept more power, I am afraid that I would not know where to start so will just start with this frequency MOD.  Suggestions, comments more than welcome.


DISCLAIMER:  DON'T FOLLOW ME CAUSE I HAVE NO CLUE ABOUT ELECTRONICS or ZVS circuits !!
« Last Edit: February 19, 2021, 05:39:50 PM by hightemp1 »

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Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
« Reply #319 on: February 19, 2021, 05:36:49 AM »

 


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