Back in the 2391 days

[Guest 004]

The problem is clearly on how the PFC was measured. Which is not clear on the question, as it says 230/400. So you either go with 230 to give 0.14, or what I am leaning with 400 which is 0.25

 

[Hawkmoon]

Assuming that a pfc can only be measured off a singles supply one at a time them doubled by calculation. I would work it out as 230v divided by 1600a pfc = 0.14 ze

Congrats - not for your answer but for having the balls!

 

[Guest 004]

Yep unclear on how the value was achieved, so hopefully this question is no longer in the databank

 

[RichardMoore]

The problem is clearly on how the PFC was measured. Which is not clear on the question, as it says 230/400. So you either go with 230 to give 0.14, or what I am leaning with 400 which is 0.25

why would you go with 0.25 on 400v ? Is it because it feels better but it wrong

 

[Guest 004]

^ Just ohms law isn't it

 

[LeeH]

You cannot use 400V as you would never get this to ground. Only short a short circuit between phases.

^ Just ohms law isn't it

 

[Guest 004]

Oh hum

 

[MDJ]

0.287 ohms

 

[Guest 004]

^ Interesting how did you get to that?

I am going with 230/1600 = 0.14 ohms

 

[Guest 004]

If the PFC given was calculated with root 3. Then 1600 would have to be divided by root 3 giving 923.8. Then it's 230/923.8 = 0.248

Don't remember the exam being that complicated really. So I am staying with 230/1600

Final Answer

You can shoot me down in flames now.

 

[Guest 004]

BTW passed 2391 in 2000

 

[Hawkmoon]

0.287 ohms

This is the answer I came up with (back in the day) - unfortunately not correct

 

[Hawkmoon]

The lecturer who showed my group the question said it was likely it was designed to mislead (or a 'trick question')

 

[LeeH]

The lecturer who showed my group the question said it was likely it was designed to mislead (or a 'trick question')

And the model answer is!!??

 

[Guest 004]

That's what we have already said