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

 

[Morley2012]

I agree with you 40/1.732 = 23.09A but I'm still learning and I was using DIVS and my triangles so I could be wrong.

 

[Pete999]

I agree with your calcs

 

[jimmymac]

Edit...got it wrong

 

[Simonslimline]

(IL = ∛ x Ip), so, ∛ x 40 = 69.28A = 70A....that's how I see it but in have got a severe dust allergy at the moment and can hardly see

But it is saying the line current is 40Amps so the phase current must be smaller 40/1.732.

 

[telectrix]

get a few beers down you. you may still not be able to see, but then you won't want to see anything.

 

[jimmymac]

But it is saying the line current is 40Amps so the phase current must be smaller 40/1.732.

YEP, told ya I couldn't see! I've been trying to edit that for the past five minutes

 

[jimmymac]

I still can't edit it! I agree....23.09A

 

[Lucien Nunes]

The connection to the supply might be delta but that doesn't mean the windings are, as they could be internally star connected if balanced. Possibly a bit of a semantic argument rather than an electrical one.

 

[Simonslimline]

The connection to the supply might be delta but that doesn't mean the windings are, as they could be internally star connected if balanced. Possibly a bit of a semantic argument rather than an electrical one.

I will post up what they say in response. I have emailed them to query the question.

 

[Lucien Nunes]

For my money it's not well worded. You said:

It would only be 40amps if it was Star connected?

But of course it doesn't say 'delta connected' either, only 'delta three phase load.' As 23A isn't a possible answer, we can infer what they meant. Of course if they spelled it out it would be too obvious. I'll give question a B- and move on...

 

[Simonslimline]

For my money it's not well worded. You said:
But of course it doesn't say 'delta connected' either, only 'delta three phase load.' As 23A isn't a possible answer, we can infer what they meant. Of course if they spelled it out it would be too obvious. I'll give question a B- and move on...

My money is on a typo, they may mean star rather than delta. All will be revealed soon

 

[Simonslimline]

So after messaging them, they said it was a typo and are sending me some combination pliers for spotting it :shades_smile:

 

[Chr!s]

There are only four currents to consider in a star connected system, so it must be delta. Assuming a resistive balanced load.

The anwer is Ipl3 - Ipl1


Ill go with 40 amps


Chris

 

[Richard Burns]

So after messaging them, they said it was a typo and are sending me some combination pliers for spotting it :shades_smile:

You will be fully kitted out soon; so long as they keep making these errors!

Not so impressed by the standard of their questions!

 

[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?