GB495253A - Improvements in or relating to alternating current watt meters and watt meter relays - Google Patents

Abstract

495,253. Power meters. COMPAGNIE POUR LA FABRICATION DES COMPTEURS ET MATERIEL D'USINES A GAZ. March 9, 1937, No. 6946. Convention date, March 10, 1936. [Class 37] In an electrodynamometer wattmeter measuring reactive power, the parasitic couple resulting from the action of the current circuit or circuits on the current or currents produced in the voltage circuit or circuits by mutual induction, is cancelled by arranging the voltage winding so that any such parasitic current is split into a number of opposing currents which substantially cancel one another out. As shown, Fig. 1, the voltage winding is divided into halves 2, 2<1>, connected in series, respectively, with a capacitance 3 and inductance 4 so arranged that the parasitic currents produced in the voltage windings 2, 2<1> are of opposite polarity and equal magnitude and therefore no parasitic couple results. The driving currents in windings 2, 2<1> are however additive and the couple produced thereby in conjunction with the current winding 1, 1<1> is proportional to the reactive power. The Specification as open to inspection under Sect. 91 states that wattmeters sensitive to active or complex power may be connected in a similar manner. Thus, in one arrangement, a correcting arrangement as in Fig. 1 is provided having in addition a series connected reactance which it is stated may be so dimensioned as to render the wattmeter sensitive to active or complex power. In Fig. 3 (Cancelled), this reactance is shown at 5. The voltage coils 2, 2<1> are electrically independent but mechanically rigid, the two parasitic couples acting thereon cancelling each other out. This subject-matter does not appear in the Specification as accepted.