Sparks comp question!

[Simonslimline]

Hi this is another question from sparks magazine competition just wondering what any of you think the answer is.

any input on this is appreciated.

Star (VL = ∛ x Vp) (IL = Ip)

Delta (VL = Vp) (IL = ∛ x Ip)

I make the answer 23.09Amps!!!


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

 

[Richard Burns]

They must mean the phase current is 40 A and therefore the line current is 70 A

 

[Simonslimline]

They must mean the phase current is 40 A and therefore the line current is 70 A

Yes it is the only way one of the answers can be correct right!

So phase current is 40Amps X 1.732 = 69.3 Amps.

So 70 will be the answer they are looking for.

Just thought i would double check before pulling them up on it.

 

[Richard Burns]

They could mean a star connected system not delta then c would be right, but a bit of a pointless question then.

 

[Simonslimline]

Yeah it must be a typo. Everyone is still putting C 40amps as the answer though. even though it cant be!!!

I had a similar thing last time with a volt drop question where everyone put the wrong answer and i didn't agree and put my answer and they sent me some tools for getting it correct.

Just makes me doubt myself seeing all these people put the same answer TBH. most of them just copy each-other i guess without even thinking.

 

[ElectroChem]

Maybe they should hire you to check their questions Write into them, at this rate you'll end up scoring enough free kit to last you a lifetime hehe.