#### SonOfAnarchy ZA

Joined Jul 13, 2011
45
hi guys i got a slight problem with a few of my practice question for a upcoming exam please if anyone can help me i would really help

question 1

a 3-phase star-connected system has 230v between each phase and neutral. the load consists of resistances of 4, 5, and 6ohms respectively in the three phases. find magnitudes of the current in the three phases and of the neutral wire

question 2

a coil has an inductance of 0.06henry and a resistance of 2.5ohms. the coil is in series with a capacitance of 6.8uf accross a 230v, 50Hz, single phase supply. calculate current and the angel of phase differece between it and the applied voltage. if the voltage is 10% harmonic of 5 times the fundimental frequency, calculate the current due to this harmonic and the total pd on the capacitance.

question 3

find the rms value of the folllowing componets of a complex wave: fundamental = 410volts; third harmonic = 57volts; fith harmonic = 25volts
fundamental = 20ampares; third harmonic = 12amperes; fith harmonic = 5amperes

question 4

a singel phase inductive circuit at 400volts 50hz has an impedance of 8 ohms and a power of 5kw. a capacitor is added in parrallel, of 300uf capacitance. find the value of the final power factor.

i would appriciate it if anyone could help me out here

#### Georacer

Joined Nov 25, 2009
5,182
Okay, why don't you post any effort or thoughts you have done so far for each question. It will really help us and you to get to the right track.

#### SonOfAnarchy ZA

Joined Jul 13, 2011
45
the problem is i dont know where to start or finish

#### Potato Pudding

Joined Jun 11, 2010
688
Break it down into which parts you understand and where you start to lose focus. This is not a good place to come to just get answers if you have learned nothing.

Show what you're missing. Chances are you only feel like you don't know anything. That kind of failure of confidence you need to try and get over.

#### Georacer

Joined Nov 25, 2009
5,182
You must have been taught some theory before being given that exercise. What formulas where you given?