Tema: Re: Koks reikalingas autotatukas 3kW varikliui.
Autorius: Levas
Data: 2011-09-07 18:06:02
cia iskreiptas variklis, jame galia nurodyta HP :) Ir dar neaisku ar tais kumeliais nenurodyta elektrine galia :)


Paprastai lenteles buna su maziau skaiciuku.


O siaip, kiek protingesne citata is interneto:
1) ELECTRICAL POWER.
The first P, for which you used the equation sqrt(3)*V*I/1,000 = 91.6 kVA, is not 'real' electrical power but Apparent Power. A more correct representation is 'S' and its units are VA or kVA. Then, real power, Pi, is the product of Apparent Power times Power Factor, or S*PF! In-turn, real input-power, Pi = Po/Eff'y, where Po = 0.746*Hp/Eff'y. (CAVEAT: metric Hp and English HP are not equal!)

2) MECHANICAL POWER.
The 2nd P, for which you used the equation, 5250*RPM/Torque or 5252*1800/115 =lb(f)-ft, is shaft horsepower, or Hp, a mechanical term. In addition, you used the synchronous speed to make the calculation. Instead, output Hp is more correctly rated at the motor's as is normally shown on its nameplate, not at its synchronous speed.
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3) RULE-of-THUMB.
In countries that rate motor output in shaft Hp, a rule-of-thumb value often used is: input kVA is approximately equal to output Hp. Note the term approximately because the real kVA/HP ratio does vary. Also note, in countries using metric units then output shaft-power is expressed in electrical units or kW.

4) MATCHING MOTOR.
Of course, in the absence of other performance data, like pf and efficiency, then you will never know its exact rating. However, using typical manufactuter's data, then the 115-A value you mentioned would yield a 3-ph, 460-V motor of 100-Hp. 

Regards, Phil Corso, PE (cepsicon@aol.com)



-- 
Bye, Levas

--
http://www.vabolis.lt

"Dovydas" <dovydas.zakas@gmail.com> wrote in message news:j4700f$pns$1@trimpas.omnitel.net...
> na að gal palyginus ir nedaug jø matæs realiai, bet kiek maèiau, tai ant 
> visø buvo maþdaug tokios lentelës kaip prisegu, kur uþraðyta el. galia?
> 
> "Evaldas" <sanya@takas.lt> wrote in message 
> news:j45nmi$h73$1@trimpas.omnitel.net...
>> "Signalizacija" <signalizacija.master@gmail.com> wrote in message
>> news:j45j1h$brb$1@trimpas.omnitel.net...
>>> Cia kuriu taip varikliu?
>>
>> Visu elektriniu motoru.
>> Jei paimsi motoro aprasyma ir jame rasi parasytus kilovatus tai tie
>> kilovatai yra mechanine (veleno) galia.(isskyrus atveji kai nurodyta, kad
>> tai pareikalaujama galia (consuming power)
>> Suprantama, juk perkanciam motora santechnikui reikia zinoti ar pasuks jo
>> siurbli/ventiliatoriu ir santechnikui visiskai px kiek elektros srebia. 
>> Cia
>> jau alektriko rupestis.
>>
>> 
> 
> 
>