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Topic Title: Can Someone Help Me With A 3-Phase Question?
Topic Summary: HNC Electrical Engineering Question
Created On: 28 April 2012 08:36 PM
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 28 April 2012 08:36 PM
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Tom1983

Posts: 3
Joined: 25 April 2011

Hi, can someone help me with a 3-phase question I am having problems with?

The specific area of the question I am struggling with is putting the impedance figures into rectangular form.

The given impedance values are:-

Za = 5kw at a lagging power factor of 0.7
Zb = 6kw at a lagging power factor of 0.9
Zc = 8kw at a lagging power factor of 0.8

Any help would be much appreciated.

Cheers
 30 April 2012 01:34 PM
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gkenyon

Posts: 4490
Joined: 06 May 2002

There are a number of web-sites that provide explanation and examples, that can be found with common search engines.

Is there anything specific that we can help you understand? Which bit is causing the problem? Do you understand what the Power Factor is, and how it relates to the Real Power and Phase Angle?

-------------------------
Eur Ing Graham Kenyon CEng MIET TechIOSH
 30 April 2012 06:12 PM
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Tom1983

Posts: 3
Joined: 25 April 2011

Thank you for responding to my query. I have in fact figured out the solution to the problem now. I do understand the relationship between the power factor with regards to the real power and phase angle, for some reason I was not, at first, able to see the solution to calculate the phase currents.

I now realise that, after calculating the magnitude and phase angles of the phase voltages, I simply divide the corresponding phase load power by its phase voltage multiplied by the power factor to get the phase current.

i.e Load A / (Voltage A x pf A) = 5000 / (259.81 x 0.7)

Many thanks again for responding

Thomas Franch
 30 April 2012 10:20 PM
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gkenyon

Posts: 4490
Joined: 06 May 2002

No problem.

You will almost always receive help from this Forum, but you will find that most contributors will help you move forward, rather than offering answers "on a plate".

I'm glad you managed to sort this out in your head; it's really easy to get bogged down with the maths for electrical engineering because you have to imagine a lot of what's going on; because of this, it's easy to have a mental block on some things.

Just let us know if you need any further nudges forward.

Kind Regards,

-------------------------
Eur Ing Graham Kenyon CEng MIET TechIOSH
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