[Oscar]

As the title states. I need a 400V 3-pole circuit breaker. The 3-pole breakers at my local big box stores are rated at 240V. What would you use?

[Coldman]

4CB325-6.jpg (53.04 KiB) Viewed 7336 times

[Poland308]

Find an electrical supply house. Lots of food service and production equipment in the industrial setting is made in Europe. So there might have one in stock. If that isn’t something you have available I have contact info for a distributor on the east coast that specializes in stuff like that. You can pm me.

[tweake]

4CB325-6.jpg

yeah that

dirty shortcut is to use three breakers and connect the arm together (they are made for that). however i have found they are prone to one phase disconnecting but not throwing the other two, so your gear is running on two phases, which is a big problem for motors. the breakers are 240v. as its 240v to neutral and 415v across the phase.

however i don't know with your guys 110v system, your 240v three phase may be 110 volts on each breaker.

[BugHunter]

https://www.ebay.com/itm/255149579426?e ... SwRpRhFugB

Not sure what enclosure you'd expect to use. I'm assuming you want a breaker for downstream of your inverter. You might also consider a disconnect box with enough room for a breaker inside. I know when you get into 480V stuff, the price goes up exponentially.

Tweak,

On this side of the pond, there's no such thing as "Standards". 3 Phase comes in many variations. There can be "high leg" systems, "Y", and others, but those high leg systems are being phased out. I do believe Oscar is dealing with an inverter to get up to 3 phase, so in his case they'll all 3 be equal legs. Pre-1990, you could have high leg systems in 240V or 480V over here. That's been done away with on all new services. That was done in the old days so folks could grab a neutral and a low leg and have typical single phase power without additional equipment. Trouble was, folks would also grab a high leg and a neutral and blow stuff up and start fires. So now, you'll have 3 equal legs, none of which come with a neutral, and to get to our typical wall-outlet voltage, you need an isolation transformer. An additional benefit of this is that now the power being used on each leg is equal as opposed to having the two low legs being used for all single phase stuff, pulling those low legs down disproportionately.

I have a high-leg system here at work, but I also run isolation transformers on every piece of equipment for any single phase power needed. This way, if wiring should ever change (swapping wires around, move a breaker, whatever), none of the single phase stuff is at risk of being blown up or catching fire. Any orientation of the 3 wires to the transformer will supply 110V at the output.

[Oscar]

The source is 400V coming from my transformer. The device is my Stel S300 welder.

[BugHunter]

I've not been on a lot lately so I may have missed a bunch of stuff. Transformer? I was under the impression you had 3 phase power via an inverter... Did you get 3P direct service?

[BugHunter]

My memory is shot... Seems to me you did get 3 phase service run into your place some time back.

So you're saying you got a transformer in order to run a welder? That would be supplied by the 240 3 phase with a breaker already. You just need a disconnect box, (or switch off the breaker when not in use as I do). Just fyi, those big transformers do pull quite a bit of power even when there's no load. I've got a big one here and I can listen to mine hum when it's powered up. Seems to me mine is 480V x 30A or so. I keep mine off unless the machine is in use. I bet mine costs $10-$15 / month just to have it on but not using any power from it.

[Oscar]

My memory is shot... Seems to me you did get 3 phase service run into your place some time back.

So you're saying you got a transformer in order to run a welder? That would be supplied by the 240 3 phase with a breaker already. You just need a disconnect box, (or switch off the breaker when not in use as I do). Just fyi, those big transformers do pull quite a bit of power even when there's no load. I've got a big one here and I can listen to mine hum when it's powered up. Seems to me mine is 480V x 30A or so. I keep mine off unless the machine is in use. I bet mine costs $10-$15 / month just to have it on but not using any power from it.

I don't have utility 3-ph service. I'm running a 30HP phase converter, as you can see in this pic. I call it the Frankenverter since it's pretty crazy looking Some say it was responsible for the near catastrophic failure of the entire Texas power grid back in February



So, yes I bought a transformer that has multiple taps and can serve to up- and down-convert 3-ph power. You can see it here underneath the welder.



So I use it to up-convert 240V-3ph in to 400V-3ph. I only have it on when I use the welder. Even though I do have a 240V/40A breaker upstream of the transformer (coming from the RPC), I still want to have a breaker post-transformer.

[Oscar]

Coldman, seems more than person has suggested those DIN rail type breakers, and I was linked some that seem like I can make them work (likely in a custom enclosure):

Automation Direct, 480V 25A 3-pole C-curve trip curve 35mm DIN Rail Mount, that look like I could make them work.

Amperage aside, Any reason I could not use those 480V 3-pole breakers at 400V and 240V (3-ph of course)? What I know tells me the lower operating voltage (compared to the breaker voltage rating) should have no ill-effects, so long as they are sized properly to protect the wiring, etc. Thoughts?

[Coldman]

Maybe you don't need a circuit breaker if you already have one, just a local isolator:

s-l200.jpg (4.27 KiB) Viewed 7284 times

Or maybe a d.o.l. motor starter with thermal overload fitted:

[tweake]

Tweak,

On this side of the pond, there's no such thing as "Standards". 3 Phase comes in many variations. There can be "high leg" systems, "Y", and others, but those high leg systems are being phased out. I do believe Oscar is dealing with an inverter to get up to 3 phase, so in his case they'll all 3 be equal legs. Pre-1990, you could have high leg systems in 240V or 480V over here. That's been done away with on all new services. That was done in the old days so folks could grab a neutral and a low leg and have typical single phase power without additional equipment. Trouble was, folks would also grab a high leg and a neutral and blow stuff up and start fires. So now, you'll have 3 equal legs, none of which come with a neutral, and to get to our typical wall-outlet voltage, you need an isolation transformer. An additional benefit of this is that now the power being used on each leg is equal as opposed to having the two low legs being used for all single phase stuff, pulling those low legs down disproportionately.

I have a high-leg system here at work, but I also run isolation transformers on every piece of equipment for any single phase power needed. This way, if wiring should ever change (swapping wires around, move a breaker, whatever), none of the single phase stuff is at risk of being blown up or catching fire. Any orientation of the 3 wires to the transformer will supply 110V at the output.

my god that sounds like a nitemare.

locally here is pretty simple, 415v 3 phase or 240v single phase.
tho most houses are 240v single phase 60 amp service (tho some higher, some lower). some towns are 3 phase 60 amps per phase service. i think there is the odd ball two phase ones.
it all down to how they balance the power down the street.

as you can imagen most people don't run big welders.
in fact EV's are starting to cause issues.

[Arno]

Amperage aside, Any reason I could not use those 480V 3-pole breakers at 400V and 240V (3-ph of course)? What I know tells me the lower operating voltage (compared to the breaker voltage rating) should have no ill-effects, so long as they are sized properly to protect the wiring, etc. Thoughts?

Yes, no problem.

The other way around could be more tricky. They would still work/trip, but likely die after a few trips as the arc that occurs inside the breakers when it trips is bigger at the higher voltage and would damage it internally quicker, so 'not advisable'. (any breaker like this has a certain number of 'trips' it's rated for.. after that they tend to become too 'trigger happy' or die because the internal contacts become too pitted/damaged..)

Many of these breakers are also suitable for DC use, but you'd need to check that specifically as the amp rating may be different.

Bye, Arno.

[tweake]

Many of these breakers are also suitable for DC use, but you'd need to check that specifically as the amp rating may be different.

Bye, Arno.

amp ratings are substantially less for DC.

[BugHunter]

I don't have utility 3-ph service. I'm running a 30HP phase converter, as you can see in this pic. I call it the Frankenverter since it's pretty crazy looking Some say it was responsible for the near catastrophic failure of the entire Texas power grid back in February

Ok, it's all coming back to me now. Yes, the pics helped with my failing memory.

As mentioned above, yes, the 480V breaker will work fine with your 400V output. It's simply a rating. I could be mistaken, but it's the AMPs that trips the breaker, and the voltage is simply a rating of what service that breaker is compatible with.

Yes, I like the idea of a DIN rail type. Especially because you can find enclosures at local surplus places for next to nothing. Fact is, you might find the whole thing at such a place. About 45 minutes drive away, I've got a great place that sells industrial surplus crap and it's just a gold-mine of deals on used equipment. It's a blast just to go shopping. I'd really like to buy one of their mixers! You know, the ones with 7.5HP 3P motors that stand as tall as I do; where you throw in 2 25# bags of flour and make pizza dough! Lol. Man, I want one!

But yea, that place has all sorts of electrical enclosures. Fact is, if you're not intending to trip the breaker often, seriously consider just a disconnect box with fuses. Then, not only is it dirt cheap (by comparison), but the fuses are only like $5 ea, and if you never blow em, what's the difference? It's also adjustable, since you can stick in whatever amp rating fuse you want.

Something like this:
https://www.zoro.com/siemens-fusible-si ... /G3078284/

I use em on all sorts of stuff here, and used, they're dirt cheap to buy. I bet you can get one for $30 or less.

[BugHunter]

my god that sounds like a nitemare.

Oh, it gets better! First, I'd bet when I last looked, there were 10 or more "Standards" of 3 phase power distribution depending on what part of the country you were in or what Utility company was supplying it.

To make matters worse, say for instance you're dealing with a "High Leg" system such as mine. 3 Legs to neutral/ground measure 120 / 120 / 208. Across any two, 240V. Ok, well, the sequence matters, obviously..... So what do the power companies and equipment manufacturers do? Well, of course the power company has the high leg in the center out at the meter. But in the building at the load center, the high leg goes on the right. Ah! Ok, that's easy! Ah... no... Now when you go to a contacter for a machine, the high leg goes back in the center!!! )(*&$)*&_%$)*_ )&*_$&*%_($&*

You get used to buying orange tape by the case....

[Oscar]

But yea, that place has all sorts of electrical enclosures. Fact is, if you're not intending to trip the breaker often, seriously consider just a disconnect box with fuses. Then, not only is it dirt cheap (by comparison), but the fuses are only like $5 ea, and if you never blow em, what's the difference? It's also adjustable, since you can stick in whatever amp rating fuse you want.

Something like this:
https://www.zoro.com/siemens-fusible-si ... /G3078284/

I use em on all sorts of stuff here, and used, they're dirt cheap to buy. I bet you can get one for $30 or less.

I had thought about it the disconnect box, but I don't like the looks of it, TBH I'd just rather have a more compact setup with a breaker in a small enclosure. I was sent some links to breakers on www.automationdirect.com and they seem to be the ticket.

[Oscar]

Maybe you don't need a circuit breaker if you already have one, just a local isolator:
s-l200.jpg

Or maybe a d.o.l. motor starter with thermal overload fitted:

I'd like to know where exactly you source your isolators. My google for that model number or even isolators in general failed to retrieve some hits where I could simply add-to-cart and just buy it outright.

[BugHunter]

I had thought about it the disconnect box, but I don't like the looks of it, TBH I'd just rather have a more compact setup with a breaker in a small enclosure. I was sent some links to breakers on www.automationdirect.com and they seem to be the ticket.

That outfit seems like they've got a good business model going. I've almost used them on a few projects at work (automation related). My guess is I'll be buying my next controllers there. (PLCs).

I have those disconnect boxes attached to probably 15 machines in the shop here. To be honest, I did blow a fuse on the bandsaw the other day but I did it with the gooseneck light that's on it, When it came apart as I was moving it, it shorted. POW. Blew one phase fuse. Got another at the hardware store next door for $0.99 (went up since last time Had their price sticker on the old one!) and was back in business. I can't recall the last time I messed with one, and I"m not sure in 23 years I ever have. For a buck every 23 years, I'm ok with it!

How often do you trip breakers?

[tweake]

my god that sounds like a nitemare.

Oh, it gets better! First, I'd bet when I last looked, there were 10 or more "Standards" of 3 phase power distribution depending on what part of the country you were in or what Utility company was supplying it.

To make matters worse, say for instance you're dealing with a "High Leg" system such as mine. 3 Legs to neutral/ground measure 120 / 120 / 208. Across any two, 240V. Ok, well, the sequence matters, obviously..... So what do the power companies and equipment manufacturers do? Well, of course the power company has the high leg in the center out at the meter. But in the building at the load center, the high leg goes on the right. Ah! Ok, that's easy! Ah... no... Now when you go to a contacter for a machine, the high leg goes back in the center!!! )(*&$)*&_%$)*_ )&*_$&*%_($&*

You get used to buying orange tape by the case....

that would do my head in.
so used to 3 phase not even worrying about what cable goes where. in fact often they are all black. if motor goes the wrong way swap a pair.

[Coldman]

I'd like to know where exactly you source your isolators. My google for that model number or even isolators in general failed to retrieve some hits where I could simply add-to-cart and just buy it outright.
[/quote]

Here's one I found on ebay.com so you should be able to order it in. There are plenty others.

https://www.ebay.com/itm/400828487878?e ... SwZvRajVf0


There are plenty of ozy sites but I'd need to check if they will ship off shore. Let me know if you want me to do this. I can always get one and post it to you .

[Oscar]

Here's one I found on ebay.com so you should be able to order it in. There are plenty others.

https://www.ebay.com/itm/400828487878?e ... SwZvRajVf0


There are plenty of ozy sites but I'd need to check if they will ship off shore. Let me know if you want me to do this. I can always get one and post it to you .

Oh ok. If that is the case, I'd rather simply go the route of the DIN rail breakers from the Automation Direct website, than have to deal with international shipments.

[Poland308]

C8BE52A6-81C3-4001-AFB3-57464C246C2D.jpeg (761.69 KiB) Viewed 7138 times

Here’s the line card for the supplier I use at work for odd or special components.

[Oscar]

Everything is out of stock at kentstore.com.

I already ordered the breakers from automationdirect.com anyways.

[Oscar]

Thanks to everyone for their unwavering support! Took me this long since I been working long hours and only have like 20-30min free on the weekdays after I get home, and weekends are for traveling around Texas

Receptacles from Left to Right:

• 240A (just pass through, same 3-Φ coming from the rotary phase converter, not up/down converted)
• up-converted 400V with a 25A B-curve breaker (right above, breaker on the left). They were out of stock on C-curve breakers, so I'm thinking it will be fine.
• up-converted 480V on a 20A B-curve breaker (right above, breaker on the right).

I still need to protect the wiring that comes out from the transformer, but for now it's no big deal as I don't work anywhere near there.