Pls i need help

[eng_zayed]

hi ...

can any body help me to solve theis problem :

1_ Phase currents at a point in an unbalanced three phase system are
Ia=2+j5,,
Ib= -3 -j,,
Ic= 0.2-j2,,

what is the zero sequence current at this point?

...........................

2_ At point (F) of a faulted three phase system, the sequence voltages in phase A are
Ea1= 0.5
Ea2= 0.2
E0= 0.8

Finde the phase to ground voltages in all three phases at point F

Hint : Eag = Ea1+Ea2+E0

Ebg = Eb1+Eb2+E0

Ecg = Ec1+Ec2+E0

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3_ A three phase system with sequence impedance , Z1 = j10 , Z2 = j8 , Z0 = 10+j12 ohm is supplied with a phase to neutral voltage , E = 4600v.

Find the currents at the fault point in phase A for

a) phase A to ground fault

b) phase B to phase C fault

c) three phase fault

d) phase C to phase B to ground fault :?:

 

[aibelectronics]

reply

GOSH! I've forgotten my 'fault' calculations!
Do you by any chance have 'A Textbook of Electrical Technology' by Theraja?