alaskan JW
Member
- Location
- Anchorage,Ak
in what kind of applications would you use this transformer set-up? What is
that high leg good for?
that high leg good for?
3-phase 4-wire delta transformer
- Thread starter alaskan JW
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I'm assuming a 120/240 transformer. These are used where you have a large number 3 phase loads and a small amount of 120 volt loads. The 208 volt high leg is unusable and is simply a byproduct of this type of system.
transf.
transf.
The only ones of these I have seen have a highly reduced neutral caacity (5% of kva, as I recall). The uses I have seen are areas such as pump house where there is a sinificant 3 phase load such as pump motors and a small 120v load such as a light, receptacle, etc.
Ideal if you have motors that need 240, and a minor 120v load.
(every time I post, I step on someone,...slow typer...sorry Trevor...)
transf.
The only ones of these I have seen have a highly reduced neutral caacity (5% of kva, as I recall). The uses I have seen are areas such as pump house where there is a sinificant 3 phase load such as pump motors and a small 120v load such as a light, receptacle, etc.
Ideal if you have motors that need 240, and a minor 120v load.
(every time I post, I step on someone,...slow typer...sorry Trevor...)
Last edited:
- Location
- New Jersey
- Occupation
- Journeyman Electrician
augie47 said:
No problem.:smile:
What is the difference in powering a motor for instance using the the high leg 208 on this system and using the 208 on 208Y/120 system. I know the first is a line to neutral load and the last is line to line. Will the load operate differently? Augie is that what you were refering to with reduced neutral capacity?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Cody K said:
Do you have a single pole CB rated for 208 volts?
breaker
breaker
Cody,
Trevor has the key as to why this isn't done. You might also view:
http://forums.mikeholt.com/showthread.php?t=62837&highlight="single+phase+breaker"
In regard to the "reduced neutral capacity", someone who understands transformer windings could enlighten us, but every 240 3 phase transformer I've seen (that has a 120v tap) has a warning that the neutral load can not exceed 5% (I think thats the number) of the transformers KVA capacity. It has to do with the windings.
breaker
Cody,
Trevor has the key as to why this isn't done. You might also view:
http://forums.mikeholt.com/showthread.php?t=62837&highlight="single+phase+breaker"
In regard to the "reduced neutral capacity", someone who understands transformer windings could enlighten us, but every 240 3 phase transformer I've seen (that has a 120v tap) has a warning that the neutral load can not exceed 5% (I think thats the number) of the transformers KVA capacity. It has to do with the windings.
You may want to look through this thread as well. http://forums.mikeholt.com/showthread.php?t=86869
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
augie47 said:
It really has to do with the laws of physics and things like magnetic fields and circulating currents. But, the fact of life is: a single core transformer connect in a 4 wire delta is limited to 5% neutral loading. Multi-core transformer banks (i.e. using single phase transformers) do not have this problem.
frenchelectrican
Senior Member
- Location
- Nord'est Wisconsin et Paris France
I will agree with Jim with this one.
The single core delta transformer is really limited to 5% load on netural tap i did check few transformer catalog books and they came up the same answer as well they did warn it.
If it was multi single phase cores that no issuse there ya can run more load if ya want to.
Merci , Marc
The single core delta transformer is really limited to 5% load on netural tap i did check few transformer catalog books and they came up the same answer as well they did warn it.
If it was multi single phase cores that no issuse there ya can run more load if ya want to.
Merci , Marc
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