Sparks comp question!

[Simonslimline]

Hi this is another question from sparks magazine competition just wondering what any of you think the answer is. Everyone who has entered has put the answer as 40Amps!!! I have posted this up here as well because more people will see it. (mods please delete the thread from trainee section)

any input on this is appreciated.

Star (VL = ∛ x Vp) (IL = Ip)

Delta (VL = Vp) (IL = ∛ x Ip)

I make the answer 23.09Amps!!! It would only be 40amps if it was Star connected?


Thanks


The line current of a Delta three phase load is 40 A. the current in the phase winding is
a) 70 A
b) 160 A
c) 40 A
d) 16 A

https://www.facebook.com/sparksmag/...1153530230348/826989007313461/?type=1&theater

 

[chcnorris29]

Delta agree 2.309
Star 40

 

[Silly Sausage]

Not so impressed by the standard of their questions!

That's two in a row, I think.
Makes me wonder about the accuracy of the rest of the site's content. (I haven't looked)

 

[Simonslimline]

That's two in a row, I think.
Makes me wonder about the accuracy of the rest of the site's content. (I haven't looked)

The last question on volt drop was just the people getting it wrong, the question was legit.

Either way i am happy to receive free tools

 

[Chr!s]

Hi this is another question from sparks magazine competition just wondering what any of you think the answer is. Everyone who has entered has put the answer as 40Amps!!! I have posted this up here as well because more people will see it. (mods please delete the thread from trainee section)

any input on this is appreciated.

Star (VL = ∛ x Vp) (IL = Ip)

Delta (VL = Vp) (IL = ∛ x Ip)

I make the answer 23.09Amps!!! It would only be 40amps if it was Star connected?


Thanks


The line current of a Delta three phase load is 40 A. the current in the phase winding is
a) 70 A
b) 160 A
c) 40 A
d) 16 A

https://www.facebook.com/sparksmag/...1153530230348/826989007313461/?type=1&theater

If the supply is connected in Delta and the three line currents are 40 amps the total current is 120 amps. You have two lines connected to one phase, both the line currents are 40 amps.

The phase currents are 40 amps


Chris

 

[Simonslimline]

If the supply is connected in Delta and the three line currents are 40 amps the total current is 120 amps. You have two lines connected to one phase, both the line currents are 40 amps.

The phase currents are 40 amps


Chris

All i can say is that a lecturer that supplies them with questions says that the answer is 23.09 Amps.

The books i was reading also suggest this. Maybe the confusion is whether the load is delta connected or the supply to the load perhaps? As Lucien put previously?

 

[Chr!s]

All i can say is that a lecturer that supplies them with questions says that the answer is 23.09 Amps.

The books i was reading also suggest this. Maybe the confusion is whether the load is delta connected or the supply to the load perhaps? As Lucien put previously?

well if the load was delta and the three line currents are 40 amps what current is flowing in the phase windings, the same?

 

[Simonslimline]

We were taught at college and in the Trevor Linsley books i have been reading that

Delta (VL = Vp) (IL = ∛ x Ip)

A question in the City & guilds 309 science and principles ask you to work out Phase current and line current of a delta connected 400v load with 15ohms resistance on each winding.

The answers were 26.6A Ip & 46.1A IL.

What am i suppose to think?

 

[Chr!s]

We were taught at college and in the Trevor Linsley books i have been reading that

Delta (VL = Vp) (IL = ∛ x Ip)

A question in the City & guilds 309 science and principles ask you to work out Phase current and line current of a delta connected 400v load with 15ohms resistance on each winding.

The answers were 26.6A Ip & 46.1A IL.

What am i suppose to think?

Your right I do apologise, maybe I should stick to Trevor linsey books. The equation I quoted earlier was to find the line current not the phase.

Chris