RPC for 3-phase Induction Heater

Hi folks,
I've been doing a lot of reading on the web and around here, and I think "I have it all figured out", but I'd really appreciate a second or third, or ... opinion. My goal is to determine I'm okay to run an induction heater from an RPC. The heater is an induction heater which has a max rating of 40A @ 240V 3-phase.

My shop: 100A 240V sub panel from my house, which has 200A. To my property I also have separate 200A service for our hvac system, so 400A total from the road.

Consulting with an RPC company, they recommend a 30HP machine based on the suggestion that you want to run at <60% capacity for an inductive load. A 30HP RPC is about 49A.

The 30hp RPC has a soft-start feature, which they say will require 1x the max current of the idler to start, which is 65-75 single phase amps.

Idle amps for the RPC are 7A single phase.

My analysis:
RPC: The soft start coming in at 75 amps will be okay to get the RPC running (based on my similar experience with the 5hp, single phase compressor, which starts fine with no flickering).

Induction heater: Turned up to 100%, this will draw 40A three-phase, which is about 70A single phase + idler or close to 80A total.

My naive conclusion is that we are okay(as long as the compressor doesn't come on. )

The induction heater would probably be running at a 30% duty cycle at 100%, with it most often running in the 50-60%, maybe. I would have to manage what is running at the same time, but overall I believe I fit within my bounds.

So my question is - is this all there is to it, or am I missing something? I am going to blow up transformers or invest in machines I can't suitably use?

(Note that I did call the power company about this, and they said something like "we don't make recommendations of that sort", so it seems like they aren't too worried).

I would appreciate any input on this.

Thanks,

Don

Not surprised the power company didn't care to get involved. Wasted phone call there. You didn't post any info on the induction heater. Make, model, and year would be important. If I recall correctly induction heaters put out RF in the kHz range. So whatever input you supply will be converted to DC then amplified through an oscillator. If the RF is generated solid state I wouldn't risk running it on an RPC, too much chance you blow the device up. If old school oscillators and vacuum tubes then well, I have no idea.

Alan

adh2000 said:

If I recall correctly induction heaters put out RF in the kHz range. So whatever input you supply will be converted to DC then amplified through an oscillator. If the RF is generated solid state I wouldn't risk running it on an RPC, too much chance you blow the device up.

Click to expand...

Yes. They do. It is however ( to my understanding ), very localized and should not wreak havoc with a properly sized and set up RPC.

I read the power company guidelines, and it says call them if you are going to install anything over a 3hp motor (which was surprising to read). So I tried to play by the rules, but they didn't seem to care. But I did my due-diligence, so they can't yell at me.

Regarding the heater, it is a new, Chinese import induction heater:

Model:LH-25A
Work Power:Three Phases
Output Power:25 KW
Fluctuating Frequency:30 - 80 KHz
Featuring: the latest MOSPET, IGBT power units and frequency conversion control techniques

I emailed the manufacturer and they indicated that an RPC would be fine for this machine.

Thanks,

Don

Any way to rewire the induction unit to 220V single phase?

neilho said:

Any way to rewire the induction unit to 220V single phase?

Click to expand...

I just contacted the manufacture, and they said "yes".

But it doesn't add up to me in terms of power. I'll start a different thread, because I think it's off the original topic.

Thanks.

The basic process is the same as a VFD, converting the incoming power to DC and then to high frequency pulses. The same issues with running on single phase apply.

Bill

I started a new thread since the single-phase seems like a possibility, but I don't see how it adds up:

http://www.practicalmachinist.com/v...s-between-3-phase-1-phase-325656/#post2839835

Thanks!