Induction Heater power Supply--Question

No, they're grounded together internally. Or they usually are, and are supposed to be.

If they were made for isolated duty, then yes.

Tim

Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website:

Can I series connect the 12 volt rails of computer power supplies to power a 20A-1000W-ZVS-Low-voltage-induction-heater?

I have one I can look at, it has a 17amp 12 volt output, I'm sure I can come up with 1 or two more. I realize I need wire the supplies to turn on and they may need a small load on 5 v supply. (5v at 36amp)

Then as long as I'm doing that, any reason I can't series the 12v and

5v supplies on each computer power supply. (Hmm, 24v, 29v, 34v, power off, switched)

Thanks Mikek

So far I have found there is a connection between the DC ground (BLK) and the AC ground (GRN). So if wired in series and the cases touch you have a short. My solution is to remove that connection (BLK to Case) on the supply at the upper potential and continue with the AC ground scheme. (Both case at AC ground)

Still looking for an answer to; Any reason I can't use computer power supplies for a 20A-1000W-ZVS-Low-voltage-induction-heater?

Thanks, Mikek

Are these the ebay ones for ~$40 that we talked about before? If so you need to keep Vin greater than 12V or it fries the FETs' (according to a youtube video.)

George H.

Yes, I have found that. There seems to be two methods to get around that.

One) remove the AC ground connection on the upper supply and Isolate the cases.

Two) Remove the DC (GRD) connection from the upper power supply and leave the AC grounds connected through the power cords.

I would think Two would be best.

Your opinion?

Mike

Yes, I'm looking for minimum 24V and possibly more. But I like Jan's plan keeping the input low to get started testing. One sales sight says the tested it at 53 Volts. They may sell a few more saying that! As replacements.

"We tested when it works 53V power supply, current can reach 30A. It can be used for DIY players to make small parts quenching, annealing and other heat treatment, heating fast, very convenient." :-)

On a sunny day (Fri, 29 Jan 2016 09:13:19 -0600) it happened amdx wrote in :

I dunno, but 1000 W at 24 V is 41 A, at 36 V 27 A so... The zero load of mine at 23.5 V is about 1.5 A with a spiral coil, bit more with original copper coil.

Must be an old computah supply, 12 V at 17 A is a lot. Be careful because I am 99.99999 % sure the metal is connected to the 0 V, so not floating, so if you put those in series keep them insulated.

yes, if you run one of them from an isolating transformer. (or cut the earth lead on one of them)

they are built with 0V grounded. one could be modified to have 12V grounded instead,

or you could put bigger (or even some!) diodes in to get a -12V output. but trying to run them in parallel could be fraught.

100 ohms should be plenty.

Can't series both 5V and 12V because they use the same trabsfomer common

500W frame SMPSU modules seem to start at $20, but the 1000W ones start at $100

--
  \_(?)_

As I recall, watching your amp meter you never got near even 20 amps. I thought you were using a 24V supply?

Probably, just junque on my shelf, but it does have a 3.3V output so not ancient.

Yes, I've seen that is a situation to be worked around.

Thanks, Mikek

Found these while looking at PS's, a fused breakout board with a connector for the PS.

The price is for 10.

On a sunny day (Fri, 29 Jan 2016 14:38:39 -0600) it happened amdx wrote in :

Yes in fact 3 x 7 V Meanwell in series The Meanwell is adjustable from 6.5 to 8 V or something, I had 23.5 total. Bought those for 5 Euro piece some years ago in a surplus shop. Can make 12 V with 2, and 24 with 3. And it are high quality power supplies.

I did go over 20 A, even for cooking, that amp meter then shows '---', although the Meanwell is rated at 20 A it did not switch off. It did when I shorted it.

IIRC I cut some PCB tracks in one one day to make it floating. Was just one corner where it was connected with a screw to the metal case. If you use mains leads with ground, as common here in Europe, then even if you keep the metal cases apart they are still connected via mains ground.

Yea, just cut of the connectors, solder wires.... better and cheaper.

Ok, I didn't notice, I may rethink my power supply.

Mikek

I wasn't planning on loading it to 36 amps, that is the max rating. :-) Mikek

Not if you need 50 volts (1000W/20A). You'd need to do more than putting them in series, plus you have an isolation problem.

Yes, if: 1) your heater will be happy with either 48 volts or

60 volts power input, 2) you can isolate the output of each supply and 3) you can find 4 or 5 PC supplies capable of 20A (at least) at 12V.

That's a non starter, too. You need at least 20 amps - that disqualifies the 17 amp supply. And even with 2 more, you'll have only 36 volts, not the 50 volts in your spec.

Ed

Cannot reach watts.

12*17=206 watts whats whut?

The circuit will operate within the specs of 12 to 48 volts, the rated current is 20 amps. It varies with the load in the work coil. It has been tested over specs at 53 volts and 30 amps. I suspect for a short time period.

12v to 48v.

No I don't need a minimum of 20 amps, the maximum spec is 20 amps. Althoug,h Jan says some of his loads did go over 20 amps, he didn't say how long he ran it over that spec. I never spec'ed 50 volts.

Here's the link where I got the specs for the unit.

Thanks Mikek

On 1/29/2016 9:13 AM, amdx wrote: 20A-1000W-ZVS-Low-voltage-induction-heater?

Just a note to anyone with the heater above. I found a seller of the capacitors used in it.

I think the price is reasonable at 5 for $5.80 free shipping.

Mikek