I Need a 400V, 3-pole, 25A circuit breaker.....what would you use?

[General Zod]

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?

 

[woodchucker]

I don't know what I would use, I would go to an electrical supply house... around here we have cooper, and I would ask for what I needed.
Because, I don't know enough to substitute .

 

[mksj]

Might help to know the size/Amperage you are looking for and if is for DIN rail or direct panel mount.
It depends on the enclosure, I would check Automation Direct, Mouser Electronics, etc.
UL489 is rated for 480Y / 277 VAC / 125 VDC, I have been using their MCB breakers for 240VAC

https://www.automationdirect.com/adc/shopping/catalog/circuit_protection_-z-_fuses_-z-_disconnects/ul_489_miniature_circuit_breakers/gladiator_miniature_circuit_breakers_(gmcbu_series)/3-pole_(1a-63a)#

600VAC

https://www.automationdirect.com/adc/shopping/catalog/circuit_protection_-z-_fuses_-z-_disconnects/ul_489_rated_molded_case_circuit_breakers_(mccb)/3-pole_mccbs,_15a-600a_(3p_series)/15a-100a_(100a_g-frame)#

https://www.mouser.com/ProductDetail/Phoenix-Contact/2907687?qs=WfzemSix46tB4UMLh%2FCoVw%3D%3D

https://www.mouser.com/ProductDetail/Phoenix-Contact/2907689?qs=WfzemSix46sjz2dEBfd2dg%3D%3D

 

[Al 1]

It sounds like you should contact a licensed electrician. Al.

 

[rabler]

Is this just for the Stel S300 you recently posted about? Or are you using the 400V transformer for something else too?
A question to run by the more code/wiring safety knowledgeable folks - wouldn't an appropriate sized breaker on the input to the transformer work fine? I.e., put a 400/230 * 25A breaker= 43.5, so roughly 40 amps, on the low side of the transformer? I would *guess* that would actually be safer as it covers shorts in the transformer.

 

[Bi11Hudson]

Rule Nr1: Hire an electrician that knows heavy industrial electrical systems. Avoid a residential "wireman", find someont that knows what the hell he's doing. There isn't space here, or the time, to bring you up to speed on all of what you need to know.

With that caveat out of the way, I must assume (ass out of me) that you have a rotary converter and need to wire the downside. The first comment is that a circuit breaker will protect the wiring, transformers, switches, and such like. It will not protect the machine itself. That's what the overloads on the starter and the local control fuse are for.

Using a fusable disconnect or breaker to protect the wiring, with THHN class insulation and AWG 10 wire to the machine. A 30 amp breaker will do fine, do not try to size the breaker to the machine load. EMT conduit is fine, it needn't be rigid pipe. Rigid pipe is "better' but a PITA to work with. Do not run the wiring concealed behind wallboard, use conduit. In my day, SO insulation on portable cable was rated for 600 volts. I don't know what the class is today.

A cartridge fuse for a 240 volt circuit is rated for 300 volts. A similar fuse for 480 (600 volts) is about twice as long and usually twice the diameter. Most any breaker for that class will be rated for 600 volts. I have seen such breakers on eBay, they come and go for availability. The important issue is that when you find one, it must be 600 volt class. 300 volt insulation will not hold up and is a shock hazard.

All 480 wiring needs to be enclosed in metal boxes. And never run 480 in the same enclosure as 240. There are exceptions, but they are the field of serious electricians, not for amateurs.

I should have scared you enough with this overview that you will find someone qualified to do this sort of work. Find him. . .

.

 

[JimDawson]

Maybe these?

https://www.automationdirect.com/adc/shopping/catalog/circuit_protection_-z-_fuses_-z-_disconnects/ul_489_miniature_circuit_breakers/eaton_480y-z-277vac_miniature_circuit_breakers_(faz-na_series)/3-pole_(0.5a-32a)#Amperage_Rating_ms=%2225A%22&start=0

 

[Aukai]

I'm sure if your playing with this voltage you know how dangerous it is, if it's like 440v you don't have to touch it, it will jump to you. I just had to say it out loud.

 

[General Zod]

Is this just for the Stel S300 you recently posted about? Or are you using the 400V transformer for something else too?
A question to run by the more code/wiring safety knowledgeable folks - wouldn't an appropriate sized breaker on the input to the transformer work fine? I.e., put a 400/230 * 25A breaker= 43.5, so roughly 40 amps, on the low side of the transformer? I would *guess* that would actually be safer as it covers shorts in the transformer.

Yes, it's for the Stel S300. I do have breaker on the low-side of the transformer, coming from the phase converter, but I still want a breaker between the transformer and the welder.

Rule Nr1: Hire an electrician that knows heavy industrial electrical systems. Avoid a residential "wireman", find someont that knows what the hell he's doing. There isn't space here, or the time, to bring you up to speed on all of what you need to know.

With that caveat out of the way, I must assume (ass out of me) that you have a rotary converter and need to wire the downside. The first comment is that a circuit breaker will protect the wiring, transformers, switches, and such like. It will not protect the machine itself. That's what the overloads on the starter and the local control fuse are for.

Using a fusable disconnect or breaker to protect the wiring, with THHN class insulation and AWG 10 wire to the machine. A 30 amp breaker will do fine, do not try to size the breaker to the machine load. EMT conduit is fine, it needn't be rigid pipe. Rigid pipe is "better' but a PITA to work with. Do not run the wiring concealed behind wallboard, use conduit. In my day, SO insulation on portable cable was rated for 600 volts. I don't know what the class is today.

A cartridge fuse for a 240 volt circuit is rated for 300 volts. A similar fuse for 480 (600 volts) is about twice as long and usually twice the diameter. Most any breaker for that class will be rated for 600 volts. I have seen such breakers on eBay, they come and go for availability. The important issue is that when you find one, it must be 600 volt class. 300 volt insulation will not hold up and is a shock hazard.

All 480 wiring needs to be enclosed in metal boxes. And never run 480 in the same enclosure as 240. There are exceptions, but they are the field of serious electricians, not for amateurs.

I should have scared you enough with this overview that you will find someone qualified to do this sort of work. Find him. . .

.

Nope, you haven't scare anyone. At least not me.....

I'm sure if your playing with this voltage you know how dangerous it is, if it's like 440v you don't have to touch it, it will jump to you. I just had to say it out loud.

I'm quite aware.

It sounds like you should contact a licensed electrician. Al.

No, thanks.

mksj, JimDawson, thanks for the links.

 

[markba633csi]

I doubt any electromechanical breaker will do you much good if there is a short in the welder.
The solid state components in there will destroy themselves way before the breaker even thinks about tripping.
Solid state stuff usually is fused, but even that is just to prevent fires not save the equipment.
Skip the breaker and save yourself some money. If the welder is not fused internally you could provide it externally.
Personally, I probably wouldn't bother. If you shut down the system when you leave it should be safe.
-M