Medição de energia (EN)

CHAUVIN ARNOUX IBÉRICA S.A.

Medição de energia (EN)

Publicado: 12 de fevereiro de 2019 · Categoria: Cadernos técnicos

Deste documento

THEORY Measurement of electrical power Instantaneous, mean, active, reactive and apparent electrical power, power factor, etc. We would like to remind you about these basic parameters in electronics and about three-phase measurement methods. Definition of electrical power proportional to the product in the case of electronic wattmeters; this current or this voltage is then applied to an analogue or digital display. At a given moment, when a current i travels from generator G to receiver R in the direction defined by the voltage v delivered by the generator (figure 1), the instantaneous power supplied to the receiver R is equal to product v.i. The apparent power S = Veff . Ieff, in VA (volt-amperes), defining the voltage Veff not to be exceeded (insulator breakdown, increase in core loss) and the intensity Ieff circulating in the receivers. i G Generator V The existence of a phase shift between the current and the voltage leads, for AC currents, to the introduction of 3 additional quantities: R Receiver figure 1 If the voltage and current are DC, the mean power V. I is equal to the instantaneous power v.i. If the voltage and current are sinusoidal AC, there is generally a phase shift between the voltage and the current (figure 2). The instantaneous values of voltage v and current i have the form: v = Vmax cos t i = Imax cos (t - ) Where , the pulse, is proportional to the frequency F ( = 2F). The power factor: P P cos = = S Veff . Ieff when the current and voltage are...