Elementary My Dear Watson 3- phase alt and power

[Lloyd]

http://www.radioelectronicschool.net/files/downloads/3phase.pdf

As the title says "Elementary My Dear Watson" some may find this boorish, it makes understanding 3-phase much easier...at least for me... I might not have had to harass Mobile_Bob as much if would have found this before I began my venture down "Custom Alternator Lane".

Can you answer without peeking?? Just for the record this is a test...I won't be grading. But if you need help with the answers, then this WP is worth the read.

Lloyd


Computing three-phase values using a wye-connected power source and a
delta-connected load
It is assumed the alternator has a line voltage of 240 V and
the load has an impedance of 12 Ω per phase. Find all missing values.
EP(A) _______ EP(L) _______
IP(A) _______ IP(L) _______
EL(A) 240 ___ EL(L) _______
IL(A) _______ IL(L)________
P _________ Z(PHASE) 12 Ω


Computing three-phase values using a delta-connected source and a wye connected
load
2. Assume the alternator has a line voltage of 4,160 V and the
load has an impedance of 60 Ω per phase. Find all missing values.
EP(A) _______ EP(L) _______
IP(A) _______ IP(L) _______
EL(A) 4160 V_ EL(L) _______
IL(A) _______ IL(L)________
P _________ Z(PHASE) 60 Ω


Computing three-phase values using a wye-connected source and two
three-phase loads
3. It is assumed that the alternator has a line voltage of 560
V. Load 1 has an impedance of 5 Ω per phase and load 2 has an
impedance of 8 Ω per phase. Find all missing values.
EP(A) _______ EP(L1) ______ EP(L2) ______
IP(A) _______ IP(L1) _______ IP(L2) _______
EL(A) 560 V__ EL(L1) ______ EL(L2) ______
IL(A) _______ IL(L1) _______ IL(L2) _______
P _________ Z(PHASE) 5 Ω Z(PHASE) 8 Ω

[mike90045]

Question

Can a oversize (say 30Kva) 3 ph transformer be used to create 3 phase from a single 120V leg ? 

[mobile_bob]

"Can a oversize (say 30Kva) 3 ph transformer be used to create 3 phase from a single 120V leg ?  "

no!

bob g

[mike90045]

Can you expand on the NO ?   too much current needed on the 120v winding?

[Tom Reed]

There is only 1 phase on one leg. You would need to rectify it to DC and run it through a 3 phase inverter, use a 120vac motor to turn a 3Ph generator, or easiest use a  3Ph variable frequency drive.

[buickanddeere]

"Can a oversize (say 30Kva) 3 ph transformer be used to create 3 phase from a single 120V leg ?  "

no!

bob g

  There is a contavaluted way with a T-Transformer and maybe a delta-wye page shift.....iirc.  Better to find a three phase VFD and supply it with single phase.