Extract the angle polar numbers

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Discussion Overview

The discussion revolves around extracting the angle from a polar notation equation related to the excitation current angle of a synchronous generator. Participants explore the interpretation of polar numbers and the calculations involved in complex number multiplication.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant seeks help in finding the angle from the equation 2300=2000+(0.5
  • Another participant questions the meaning of the terms 4<90 and 0.5
  • A different participant proposes that the equation represents polar notation and suggests a corrected interpretation involving complex numbers, leading to a calculated angle of x = 35.0996°.
  • The original poster clarifies that they are indeed using polar notation and provides context about the equation representing the excitation current angle of a synchronous generator.
  • Another participant corrects their earlier misunderstanding, emphasizing the need for complex number multiplication rather than vector inner product, and provides detailed calculations to derive the angle.
  • They confirm the calculations and results using a calculator, showing that the values align with the original equation.

Areas of Agreement / Disagreement

Participants generally agree on the use of polar notation and the method of complex number multiplication, but there is some initial confusion regarding the notation and calculations. The discussion reflects a collaborative effort to clarify and refine the approach without reaching a definitive consensus on the initial interpretation.

Contextual Notes

There are limitations in the clarity of the original notation and potential typos that may affect the understanding of the problem. The discussion also highlights the dependence on correct interpretations of polar notation and complex number operations.

commelion
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hi

can anybody advise on this, need to find the angle out of the following

2300=2000+(0.5<x).(4<90)

got as far as

300/4<90 = 0.5<x

= 75<90= 0.5<x

is this correct and anybody able to finish this off

regards
 
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What is 4<90 and 0.5<x ?
 
I think he means polar notation

a \angle ω = a ( cos ω + j . sin ω )

but the OP formula seems to have a typo of some kind; the only expression I can imagine that makes sense is this

2300 = 2000 . ( 0.5 \angle x ) . ( 4 \angle 90 )
= 2000 . 0.5 . 4 cos ( 90 - x )

x = 35.0996°

May be that, or not...
 
Last edited:
hi yes it is polar notation, got my notation and common sense mixed up (late one last night)

the equation repersents the excitation current angle of a sychronous generator, ( Ia ∠ x ) stands for stator amps at some angle

(2300∠ 15 ) = (1154.7∠ 0) + ( Ia ∠ x ) . ( 4 ∠ 90 )

can some check if

( Ia ∠ x ) = ((2300∠ 15 ) - (1154.7∠ 0) / ( 4 ∠ 90 ))

= (305.4∠-61)

can someone confirm this for me please, if I am wrong please correct ?
 
ah, it's Ia instead of 4... 4 would never get a valid value... that makes sense now; also, if I remember electrics right, you're doing a complex number multiplication, not a vector inner product... so ( a ∠ b ) . ( c ∠ d ) is (ab) ∠ (b+d)... instead of (ab) ∠ (b-d) as I wrote above

so

(2300 < 15) = (1154.7 < 0 ) + ( I < x ) . ( 4 < 90 )
(2221.63 + j 595.28) - ( 1154.7 + j 0 ) = ( I < x ) . ( 4 < 90 )
(1066.93 + j 595.28 ) / ( 4 < 90 ) = ( I < x )
( 1221.76 < 29.16 ) / ( 4 < 90 ) = ( I < x )
( 305.44 < -60.84 ) = ( I < x )

it looks good; confirming result with my trusty Texas calculator:

(2300 < 15) = (1154.7 < 0 ) + ( 305.44 < -60.84 ) . ( 4 < 90 )
(2300 < 15) = (1154.7 < 0 ) + ( 1221.76 < 29.16 )
(2300 < 15) = (2299.99 < 15)
 
thanks for that


regards
 

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