Primary Circuit Breaker for 230V 50Hz Transformer

[fifty60]

I have a transformer that will be used on a 230V 50Hz supply. It is my understanding that all 230V 50Hz is derived from a single ungrounded line conductor and a grounded line conductor. I know that it would be OK to use a double pole circuit breaker since it is breaking both the grounded and ungrounded conductor at the same time.

I would like to protect the primary with just a single pole breaker. Am I right saying that this would suffice? Can anyone think of any circumstances where 230V 50Hz would not be derived from a single ungrounded and single grounded conductor? Would it be OK to use a single pole breaker only in this situation?

 

[GoldDigger]

In general under the NEC it is allowed to interrupt the grounded conductor with a switch or OCPD if it also interrupts all ungrounded conductors at the same time.

 

[fifty60]

Understood. If it were 240V 60Hz, here in the US I would have to use a double pole breaker since neither line is grounded. I am making the assumption that ALL 230V 50Hz is derived from an ungrounded line and a grounded line. Is it correct to say this? I know the voltage is 230V 50Hz, but it could be 230V 50Hz in Europe or it could be 230V 50Hz in Asia....

Is all 230V 50Hz derived from a gounded line and an ungrounded line? Does anyone know of any exceptions?

 

[donaldelectrician]

Understood. If it were 240V 60Hz, here in the US I would have to use a double pole breaker since neither line is grounded. I am making the assumption that ALL 230V 50Hz is derived from an ungrounded line and a grounded line. Is it correct to say this? I know the voltage is 230V 50Hz, but it could be 230V 50Hz in Europe or it could be 230V 50Hz in Asia....

Is all 230V 50Hz derived from a gounded line and an ungrounded line? Does anyone know of any exceptions?

Isn't that the Y point ?




Don

 

[fifty60]

Is all international 50Hz derived from 400Y /230 VAC? Or can I find some split phase 230VAC similar to our 120VAC that does not use a grounded neutral?

 

[fifty60]

Ah yikes, too early, I realized when I was brushing my teeth the error in what i justed typed....US 120 is split phase between a hot conductor and a grounded conductor. The question is still the same...is 220-240VAC 50Hz always between hot and a grounded neutral?

 

[kwired]

Is all international 50Hz derived from 400Y /230 VAC? Or can I find some split phase 230VAC similar to our 120VAC that does not use a grounded neutral?

From recollection of past discussions with some of the European members that lurk here, most single phase services/supplies in the cities is only one leg and the neutral of a 400/230 Y system. But they do have single phase supplies in the rural areas - but they would be a simple single phase transformer with two wire secondary that is 230 volts with one lead grounded.

 

[fifty60]

Do you think the same would apply to Asian countries?

 

[kwired]

Do you think the same would apply to Asian countries?

Don't know, but if you have 230 volts single phase with a grounded conductor you only have two choices AFAIK, 230 volts winding with one end grounded(which can include one leg of a three phase wye system with grounded neutral or one side of a corner grounded delta that includes the grounded phase), or 230 volts with a midpoint grounded.

 

[petersonra]

If this is going overseas I don't think you can apply US requirements. A lot depends on what you are actually doing but if the CB is also the main CB for your panel, I think it is a requirement in Europe that it also break the neutral.

 

[fifty60]

Yes, overseas somewhere but could be anywhere that has 230V 50Hz. The only 230V 50Hz I am concerned with at the moment is the standard 16A wall outlet variety---the overseas equivalent of US 120V 15A or 20A..according to the standard I am using the 16A wall outlet provides the short circuit protection, but I still need to add a circuit breaker for overload protection.

I would prefer to just add the circuit breaker in the ungrounded conductor, ie a single pole breaker instead of a two pole breaker.

 

[petersonra]

Yes, overseas somewhere but could be anywhere that has 230V 50Hz. The only 230V 50Hz I am concerned with at the moment is the standard 16A wall outlet variety---the overseas equivalent of US 120V 15A or 20A..according to the standard I am using the 16A wall outlet provides the short circuit protection, but I still need to add a circuit breaker for overload protection.

I would prefer to just add the circuit breaker in the ungrounded conductor, ie a single pole breaker instead of a two pole breaker.

I would suggest getting a copy of the appropriate equipment standards for the equipment you want to supply for the countries you want to supply them in and see what the requirements actually are. It may be different from country to country.

 

[Tony S]

For the UK there would be no problem with single pole switching/protection as we use 433/250V Yn. (Believe me, you will not find 400/230V. It’s a figment of the IET and EU’s fevered imagination.)

If this is for machine control then there’s a whole raft of legislation to comply with. Unlike BS7671 it is statutory law. For European use it will need CE approval.

As for split phase, some farms still use it, but they are few and far between. They are 480/240V

 

[fifty60]

Thanks, this was all very helpful.