120/208V single phase panel amperes

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jim dungar

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petersonra said:
I can't say I have ever seen a 120/208V single phase panel. Seen a lot of 120/240 Volt single phase panels wired up to 120/208 though.
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They are very common for the individual unit feeds in large apartment complexes.
No special equipment is required.
 
I

Ingenieur

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The sizing math is the same for 120/240 and 120/208
the difference being with 240 the N i is 180 deg opposed and cancels 1:1
ie if both legs balanced then N = 0

With 208 only a 120 deg difference so only cancels (cos 120):1 or 0.5:1
moot since N is full sized
eg 100 A on each leg (phase?) N is 50 A
 
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don_resqcapt19

don_resqcapt19

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Ingenieur said:
...

With 208 only a 120 deg difference so only cancels (cos 120):1 or 0.5:1
moot since N is full sized
eg 100 A on each leg (phase?) N is 50 A
Click to expand...
If you have two legs of a 3 phase wye system and 100 amps on each leg, there will also be a 100 amps on the neutral.
The calculation is the square root of the quantity (A² + B² + C²) - ((A)(B) + (B)(C) + (A)(C))
where A = A phase current, B = B phase current and C = C phase current
 
I

Ingenieur

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don_resqcapt19 said:
If you have two legs of a 3 phase wye system and 100 amps on each leg, there will also be a 100 amps on the neutral.
The calculation is the square root of the quantity (A² + B² + C²) - ((A)(B) + (B)(C) + (A)(C))
where A = A phase current, B = B phase current and C = C phase current
Click to expand...

isn't In the phasor sum of the line I's?
I may be wrong
I'll crank it out later
basically Ia ang 0 + Ib ang 120
got me thinking now lol
 
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