3 Phase For Beginners! Help Needed!

[Earthwrm]

Hey Everybody,

What a useful mine of knowledge this forum is! I hope someone can help with my problem...

Allow me to start by saying I'm not an electrician, so please don't be too technical with me!
I have recently acquired a 6kw 3 phase oven for baking jacket potatoes, as my partner and I wish to start a mobile catering business. The problem is, I bought this oven naively not knowing it was 3 phase, or even what that was (I'm learning but don't ask me to try and explain it!). Apparently it is supposed to be hard-wired in (according to websites I have found) but the people I got it off had it in a van and the cable has a big red 5-pin plug on the end, so I guess it must be portable to a certain extent, although it is huge and I have to move it around on a sack trolley as it has no permanent home yet! Basically I'd like to know how best to run the oven (or if I should even hang onto it) as everywhere I look it seems 3 phase is a pain to sort out and all references seem to be in regard to running motors and workshop equipment. As it is a 6kw oven, would it be possible to run off a converter/inverter, it's own generator, or something else? Or would it be possible to convert it to good old single phase which I could hook up anywhere?

Thanks In Advance

Martin

P.S. I'm sorry if this is a stupid question, but if you don't ask you don't learn!

 

[sparkyspike]

Are you intending to run off the mains or a generator? Also, does it say anywhere in the manual whether it is suitable for use on single phase? It could just be a question of how it's wired up. Then again it might not.

 

[Steve]

A lot of mobile catering equipment such as this are gas powered. Thinking burger vans etc.

If you're running off mains power, you'll need a 3 phase outler nearby, only normally found on commercial and industrial premises. You'll also find them at fairgrounds, but these will be generator supplied.

As for a single generator, 3phase ones are large and expensive.

However, the oven may be suitable to connect to single phase electric, provided your single phase electric is able to supply 6kw. Again, you'll need a large generator, or a single phase 32A circuit. (Forget this if it has a fan, the fan may be wired to all 3 phases and will not work on one. We have a 3ph oven at work, its fan is wired to all 3, so it can be reversed)

In my opinion, you should sell it and get a gas one. Much easier, long term.

 

[RF Lighting]

It might well be 6kW per phase. (Think about them CDF ovens at your place Steve )

OP, can you have a look around on the oven for the rating plate, ant tell us everything it says on there, or upload a photo of it?

(The rate plate is a small usually metal plate somewhere on the appliance which details things like input power, voltage, frequency etc)

 

[Steve]

It might well be 6kW per phase. (Think about them CDF ovens at your place Steve )

The rotisserie ovens are 11kw total load, about 4kw/phase, I cant see the bread ovens being more TBH.

 

[Earthwrm]

Wow! Thanks for the speedy replies folks!

There's a plate on the back which has the oven model, serial no, wattage (6045) and it says 3PH+N+EARTH, and below that 415V 3PH.

The oven IS fan-assisted too.

Unfortunately it didn't come with the manual but I'm waiting for a reply from the manufacturers to see if they can supply a replacement, but they are very slack so I'm not holding my breath right now.

Our first location is hopefully a small music festival based on a farm, where I assume they have some serious power for all the band equipment etc. I'm waiting for a reply from them to see if they can supply the necessary power to us, but if not I'd like to figure out what my alternatives are.

Not that it's much use, but the oven in question can be viewed here:

http://www.kingedward.co.uk/majesty_potato_baker.html

Thanks Again!

 

[breezer]

sell it.

the page you linked to says

3 phase 6kw only.

 

[Steve]

Do you NEED 100 spuds per hour?

and as breezer says, unless you can guarantee a 6kw 3ph supply at all your sites, its a wasted investment. 3 phase generators are expensive and large.

Perhaps a smaller gas oven would be better. Normally, mobile caterers use gas appliances, and a generator for things such as a kettle, toaster, microwave, fridge, lights.

Sell the oven and invest in a large single phase generator.

 

[RF Lighting]

As your oven is fan assisted, it may be impossible to convert to single phase, and an invertor of that capacity is scarry amounts of money.

(An invertor allows a TP appliance to run on a SP supply)

Sorry, but I'd have to lean towards selling it too.

 

[Steve]

I'm only guessing that the fan runs on all 3 phases.

The one in our oven at work runs a time on forward and a time on reverse, and it is VERY quick to change direction, from several thousand RPM to reverse several thousand RPM (after slowing for about 10 secs, but its very free to spin, takes a good 90 seconds to standstill).

This is why I assume its 3 phase.

And it may not apply to all ovens.

Our oven has a built in computer to control everything! All the cycles are programmed in, no thought required.

 

[Earthwrm]

Thanks for the advice guys.

I figured that we didn't necessarily have to bake 100 potatoes per hour, or could use it for baking other stuff too. At the time it seemed like a bargain as the RRP is £2500 and we got it for much MUCH less than that on eBay, but I guess nobody else was bidding as they know what a pain the whole 3 phase malarky is!

With any luck we could make a profit selling it on anyway...

Out of interest, what spec generator would I require to power it? Could I just ask HSS for a 6kw 3PH genny or would I require more info than that? And I suppose a converter is out of the question?

I guess I'll go and eat some humble pie (rather than potatoes, unfortunately)...

 

[bhm1712]

it is simply not viable to use an converter to power a 6kw 3 phase oven, especially if it is 6kw per phase. an converter that size would be in excess of £800 and would be about 800mm by 500mm in size...normally they come with a motor generator built into the unit.

 

[Steve]

Smallest gen I could fine at HSS for your needs is

http://www.hss.com/g/41340/Generator-40kva.html

the 10kw one is only 240 volt, you need 400v,
but the smallest 400v one is 40kva.

£276 a day, sadly.

 

[bhm1712]

go here

http://www.isomatic.co.uk/3phConverter.htm

the A6 is the one you would need, over 800 quid and big!

 

[Stoday]

The oven itself could be connected to run on single phase if it's star and not delta connected. Star connection is almost certainly the case, especially as there's a neutral in the power connection.

That leaves the fan. Only a small invertor would be needed to power the fan if it's three phase.