Short circuit current

[An-Ton]

I had a question on the Masters exam, I do not remember the exact question but if you loose a leg on a 3 phase system which would be effected the most by the short circuit current,
a. lights more than motors
b. motors more than lights
c. motors by 125%
d. lights by 125%

Sorry not very detailed, I picked motors more than lights since the motor will not even work when a leg has been lost, but wanted your opinion on this question.

Thankyou!

 

[Buck Parrish]

B..........................

 

[chris kennedy]

Buck, read the question again. In the OP's scenario the motors would be more forgiving, no?

EDIT: BTW An-Ton welcome.

 

[Buck Parrish]

Buck, read the question again. In the OP's scenario the motors would be more forgiving, no?

I was thinking a three phase motor.
But surely what ever light that is on that leg that is out. The light won't come on at all.

 

[iwire]

What does the question have to do with short circuit current?

 

[grantcool]

What does the question have to do with short circuit current?

Yeah, I was wondering that too.

 

[Mule]

Could you re-phrase your question please.....

 

[trojans4]

Depending on the motor if you lost one of the three legs while it was running it would still run but not as well. As far as the lights, the ones on the two working legs would still work but obviously the one on the lost leg would not.

 

[mikeames]

Very poor question. Too many variables or missing info...... What type of 3 phase system? How the heck can you determine whats effected more if a motor does not run vs a bulb not lighting. To me their both affected the same. If they wan test your knowledge then they need to do a better job writing the question.

 

[S'mise]

Yes confusing, but i would say B also. (because if you lose one leg you probably have lighting circuits that are on the other phases)

 

[jason]

The lights on the lost leg could work also. They would be dim of course, but I've seen it more than a few times.

 

[chris kennedy]

What does the question have to do with short circuit current?

Total circuit impedance has been reduced?

 

[hillbilly]

I had a question on the Masters exam, I do not remember the exact question but if you loose a leg on a 3 phase system which would be effected the most by the short circuit current,
a. lights more than motors
b. motors more than lights
c. motors by 125%
d. lights by 125%

Losing a leg and having a short circuit could be two entirely different things.
The question makes no sense...to me anyway

steve