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Answers Please. Electrical Technology.

1. A load of 2.5kW takes a current of 12 Amp from a 230 Volt supply. Calculate the power factor.


2. Three single phase loads are to be connected to a three phase supply. All at unity power factor. The loads are,


i, 60 Amp.


ii, 50 Amp.


iii, 40 Amp.


By any method determine the neutral current.


Z.
Parents
  • ebee:

    90.57971 by plastic brain - a.k.a a calculator..


    15.5A by a rule and pen on the back of an envelope. (Guessed the angle by the "Rack of the eye" method)


    Next calculation I might use a "Guessing Stick" Well that`s what our tutors used to call a slide rule as calculators (plastic Brain) were just starting to appear on the scene. 

    I can`t remember a slang name for those adding machines that were like a mini cash register with levers, a handle and moveable carriage. We thought they were brill though, 4 in the whole school and was a treat to get to use one for a few minutes , I guess it was the second half of the 60s and I think they were about £40 each which was a lorra lorra money back then


    Mind you, our school had a maths teacher (not my teacher, I had one of the others) that actually gave one girl 101% in a maths test - 101% ? yes 101%, she answered all the questions correctly plus her work was so neat and so well set out that he gave her an extra one per cent on top. 101% and that was at a Grammar type school !


    Who threw that? Stop talking at the back. Put that gum in the bin Don't forget that the power factor has to be less than one. Put that away John.


    Z.


Reply
  • ebee:

    90.57971 by plastic brain - a.k.a a calculator..


    15.5A by a rule and pen on the back of an envelope. (Guessed the angle by the "Rack of the eye" method)


    Next calculation I might use a "Guessing Stick" Well that`s what our tutors used to call a slide rule as calculators (plastic Brain) were just starting to appear on the scene. 

    I can`t remember a slang name for those adding machines that were like a mini cash register with levers, a handle and moveable carriage. We thought they were brill though, 4 in the whole school and was a treat to get to use one for a few minutes , I guess it was the second half of the 60s and I think they were about £40 each which was a lorra lorra money back then


    Mind you, our school had a maths teacher (not my teacher, I had one of the others) that actually gave one girl 101% in a maths test - 101% ? yes 101%, she answered all the questions correctly plus her work was so neat and so well set out that he gave her an extra one per cent on top. 101% and that was at a Grammar type school !


    Who threw that? Stop talking at the back. Put that gum in the bin Don't forget that the power factor has to be less than one. Put that away John.


    Z.


Children
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