230V 50Hz overseas (Singapore) is like our 120V 60Hz here in the US. What I mean by that is both voltages to ground are the nominal voltages. They are not phase to phase voltage but are phase to ground voltages. If I want to fuse a .5 KVA 230V to 115V transformer, I will use a 3A primary fuse and nothing on my secondary. But, I should not fuse a grounded conductor right? So the 230V coming into the transformer will be 230V from 1 leg to ground. So do I just fuse one line of the transformer? Anyone have any experience/insight into this?
Overseas Transformer's
- Thread starter fifty60
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In UK, usual distribution is from the star (wye) secondary of a 400V line to line so 230V line to neutral transformer.
The majority of residential and quite a few light commercial premises are served with 230V line to neutral. But note that is line to neutral.
Don't confuse neutral with ground.
The neutral is still grounded though right? I cannot fuse a grounded conductor because I never want to break my path to ground. For 230V European equipment, is it common to have the neutral phase grounded? I am taking my transformer from a 230V single phase source, and stepping it down to 115. I know that one of my secondary legs will be grounded. Would you recommend that I fuse both legs of the primary, or should only one of the primary lines be fused?
Yes, as a rule. there are some exceptions. But neutral remains the neutral, whether grounded or not.
Agreed.
Neutral phase is a rather odd term..
It is common to have the neutral grounded (earthed), usually at the local distribution transformer.
What we have for our local supply is an 11kV delta to 400V star 1500kVA transformer. It supplies line to neutral voltage to a number of residences with the load being distributed between the phases.
I would not recommend fusing the neutral, grounded or otherwise.
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- Placerville, CA, USA
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- Retired PV System Designer
I feel that! Just do not spend a lot of time looking for the neutral that you just know is always there somewhere when you are trying to use an imported 120V load. :roll:
It may be easier if you think of their system, as was mentioned earlier, as either 230/460 3-wire or 400Y/230 4-wire instead of just "230".
The 4 wire 400 Star is easy enough to understand, 400V between phases, 230V phase to neutral wire. I don't quit understand the 230/460.
I know that our phase to neutral 120V is really split phase, or half of a 240V phase. The 240V here in the states is 240V phase to phase, but in actuality it is only one phase, single phase.
Is the 230/460 really two 230V phases 180 degrees out of phase with each other? This would require a single phase of 460V, right?
I know that our phase to neutral 120V is really split phase, or half of a 240V phase. The 240V here in the states is 240V phase to phase, but in actuality it is only one phase, single phase.
Is the 230/460 really two 230V phases 180 degrees out of phase with each other? This would require a single phase of 460V, right?
- Location
- Placerville, CA, USA
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- Retired PV System Designer
Basically, and I cannot say with certainty that it is used much at all over there. The L1-to-L2 phase voltage would be 460.
But I can be certain that whenever I see 230V 50Hz it will be 400Y or 230/460? Either way if 230V is the nominal voltage, it will be referenced to ground. 400 or 460V will be between phases.
I am reading through some older posts hoping to get a better intuition for the power circuit I am dealing with. Current is indeed flowing from the 230V leg through the load and back to the transformer on the neutral leg. Even though the transformer leg is grounded, the current does not travel to ground at this point, but goes back through the transformer and through the load, and then through the neutral again, and then through the transformer, load, neutral again, of course, switching directions 100 times a second. Is this correct? The 400Y distribution transformer is grounded, and the neutral is connected to this ground, but no current flows to ground unless another conductor in the system is grounded through a ground fault?
The above description also holds for secondary's of control transformers? Anyone willing to elaborate on that would be much appreciated.
Also, is there an official source that I can look up say, for Singapore or Korea that I can look at and determine what kind of power system they have? I know there are several on the net, but I would like to have one recommended from the forum.
Also, it is easy to find diagrams of 460V transformers that have two fuses on the primary. If anyone can find diagrams or resources showing fusing for 230V transformers on a 400Y or 230/460V system, that would also be appreciated. Are there any arguments for grounding both primary legs of a 230V circuit derived from a 400Y source?
I am reading through some older posts hoping to get a better intuition for the power circuit I am dealing with. Current is indeed flowing from the 230V leg through the load and back to the transformer on the neutral leg. Even though the transformer leg is grounded, the current does not travel to ground at this point, but goes back through the transformer and through the load, and then through the neutral again, and then through the transformer, load, neutral again, of course, switching directions 100 times a second. Is this correct? The 400Y distribution transformer is grounded, and the neutral is connected to this ground, but no current flows to ground unless another conductor in the system is grounded through a ground fault?
The above description also holds for secondary's of control transformers? Anyone willing to elaborate on that would be much appreciated.
Also, is there an official source that I can look up say, for Singapore or Korea that I can look at and determine what kind of power system they have? I know there are several on the net, but I would like to have one recommended from the forum.
Also, it is easy to find diagrams of 460V transformers that have two fuses on the primary. If anyone can find diagrams or resources showing fusing for 230V transformers on a 400Y or 230/460V system, that would also be appreciated. Are there any arguments for grounding both primary legs of a 230V circuit derived from a 400Y source?
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texie
Senior Member
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- Fort Collins, Colorado
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- Electrician, Contractor, Inspector
I think a good analogy here is that systems on your side of the pond would be as if we used 480/277Y (a standard voltage for the US) for residential distribution but only brought 1 ungrounded and the neutral to a residence and had a 277 volt system in a residence. With the exception of a slight difference in voltage (and of course you use 50 hertz) it would be similar. But as you probably know, on our side of the pond, we typically have 120/240 single phase for residential service that is derived from 1 phase of the primary and the primary neutral.
weressl
Esteemed Member
Hm, I always thought - because that's how I was taught - that a phase conductor becomes 'neutral' WHEN it is grounded. The explanation was that at that point it becomes earth potential, which is considered the absolute 0, thus neutral.
abhishekbt
Member
- Location
- California
I would also not recommend fusing the neutral, grounded. Neutral should be kept neutral and should have any phase. I am trying to give my opinion, but I do not have any expertize in handling the connections.
Is there a UK equivalent to NFPA 79? I know we are dealing with CE in the UK (though they are not in the Eurozone), but I am looking for a standard that is similar to the NEC or NFPA 79 that gives you exact figures and calculations.
Also, my question regard the difference between 400V and 380V is still out there. Most of the UK systems are 400Y. I see a lot of times the voltage is listed as 380V. Is this similar to the United States when we see 480V and 460V? The lower voltage takes into account the voltage drop on the supply conductors, whereas the higher voltage is taken at the supply transformer?
Also, my question regard the difference between 400V and 380V is still out there. Most of the UK systems are 400Y. I see a lot of times the voltage is listed as 380V. Is this similar to the United States when we see 480V and 460V? The lower voltage takes into account the voltage drop on the supply conductors, whereas the higher voltage is taken at the supply transformer?
The star point on the star (wye) winding is commonly referred to as the neutral.
This from one of tour suppliers:
Primary: 11000V + & - 2.5 & 5.0% 3phase 50Hz Delta
Secondary: 2 x 690V @ no load
Rating: 2 x 1250kVA ( 2500kVA total )
Vector group: Ddoyn11
It's for a 12-pulse VFD.
n in this case refers to the star point of the secondary star winding or neutral.
From the internet
Winding connection designations
High Voltage Always capital letters
Delta - D
Star - S
Interconnected star - Z
Neutral brought out - N
Low voltage Always small letters
Delta - d
Star - s
Interconnected star - z
Neutral brought out - n
I don't know what NFPA 79 covers, so I can't answer that.
fifty60;1506901}I know we are dealing with CE in the UK (though they are not in the Eurozone) said:
JDBrown
Senior Member
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- California
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- Electrical Engineer
Whether or not a conductor is "neutral" has to do with where it is connected in the system, not whether or not it is grounded. If grounding a phase conductor made it the neutral, corner-grounded delta systems would be even more confusing than they already are.
And what about high-impedance-grounded or ungrounded systems? :blink:(Disclaimer: I did not know any of this until I started frequenting these forums a few months back. Thanks for the lessons, everybody.)
weressl
Esteemed Member
Whether or not a conductor is "neutral" has to do with where it is connected in the system, not whether or not it is grounded. If grounding a phase conductor made it the neutral, corner-grounded delta systems would be even more confusing than they already are.
(Disclaimer: I did not know any of this until I started frequenting these forums a few months back. Thanks for the lessons, everybody.)
That may be, but I am so old that I have learned that definition BEFORE the NEC ever bothered to define it........:rotflmao:
JDBrown
Senior Member
- Location
- California
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- Electrical Engineer
That doesn't necessarily make you all that old -- I just checked, and the NEC didn't define Neutral Conductor or Neutral Point until 2008. :roll:
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