Search results

I would love to have a copy. thanks for sharing.

Use the plus sign when the power factor is lagging (the most common case), and the minus sign when the power factor is leading.

Congrats for all those passing. And good luck for those waiting. I passed  Thanks to all my friends in this forum, it was great time and experience. Wish you all the best.

What is the (angle) relation between line current and phase current in a delta connection? and does the line current direction make any difference in this relation? I mean, Line current flowing in- Line current flowing out.

Still the question, after calculation done, which way to go? I am thinking of going home.

can some one confirm which way to go for Motor feeder  SCGF protection

Does the zero sequence current flow on the Y connected winding of the XFR?

@Stephen2awesome Thanks.. This is an interesting one. So for the motor overload I should go for the next lower level. But for the conductor I am allowed to go for the next upper level, right? is it applicable also for the short circuit/ground fault?

Yes, it is .5 pu and you will have draw the sequence diagram for LL fault to get the answer.

is there on the NEC (the part we are usually tested on) a requirement to go for the (next lower level) on the overcurrent protection (overload, ground fault and short circuit) for conductors and motors? (branch circuit, feeders). All I have seen is (next upper level)

I know what you are trying to say, and you are right. Actually, what is going on is that, the secondary voltage of XFR T2 is no longer 13.8 Kv due to the voltage drop of the line and the transformers. and this becomes more evident as high currents flow in the system. The secondary voltage of T2...

Of course, if I am not interested in the phase angle. 

Actually, transformers Impedances and TL impedance doesn't matter at all. I just need to know the load resistance (which is provided 200 ohm) and the voltage at the load (provided 13.8 Kv)  to calculate the current VLL/sqrt(3) / RL  =39.8 A (same answer)

Thanks for the question, it is good for practice. However, for this specific problem we can directly calculate the current in the load side and then using the transformers ratio to obtain the current on the other zones, right? Thanks again for the detailed explanation on the link.

Thanks @rg1 I just wanted to confirm.

Is the solution for this problem correct?

 I couldn't see from where he got this relationship.  Impedance of the generators could be any value.  If I would solve this question is and the impedance of the generator is not given,  I would consider it as in finite bus.

Impedance or pu impedance is a complex number having both terms X and R. X/R = tan(theta) .. the impedance angle. if for two equipment, say generator and transformer, having same X/R ratio, then both have the same impedance angle and you can simply add the pu impedance. if X/R ratio is...

The total loss at full load of a single phase transformer is estimated to be 2000 W. The transformer maximum efficiency occurs at 45% of the full load. The estimated no load loss of the transformer is approximately?