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A METHOD OF DETERMINING CHANGES IN THE WEIGHT OF ELECTRIC POWER NETWORKS CAUSED BY MODIFICATIONS TO POWER SYSTEM PARAMETERS IN HIGH-SPEED VESSELS

The night-time operation of high-speed passenger vessels requires that they be fitted out with auxiliary equipment to ensure after-dark navigational safety. This entails an increase in the output and, thus, in the weight of the ships electrical power systems. This weight increase can be mitigated by going at the source to higher feed voltages and by switching from direct to alternating current. The weight of the cable system of high-speed hydrofoil vessels is known to comprise as much as 37 percent of the weight of the entire electrical power plant. On the basis of empirical formulas showing the relationship of the weight of the wiring to their rated load currents it is possible to analyze the effect of the kind of current, voltage, and frequency on the weight of the electrical circuitry of high-speed vessels employing mark BPVL and LPRGS wiring. It is evident from these formulas that, all other factors being equal, the weight of BPVL wiring from the rated current level varies proportionally to the 1.4th power, and that of LPRGS wiring--proportionally to the 1.53rd power. Specifically, this analysis indicates that when switching over (with no change in voltage) from direct to single-phase alternating current in a two-wire system there is a 180 percent increase in the weight of BPVL wiring, and a 225 percent increase when switching to three-phase a.c. in a three-wire connection. The transition from 24-V d.c. to 127-V single-phase a.c. gives a 73 percent weight reduction, and to a three-phase 220-V system--an 85 percent reduction. These figures were derived for a system power factor of 0.8 at 50 cycles. A correction factor can be introduced to allow for frequency change. In such calculations it is important to remember that when going from one voltage to another, there is an actual reduction in the weight of the electrical wiring to a lesser value, although the cross-section is not always diminished, since this may be impractical from the standpoint of mechanical strength, etc.

  • Authors:
    • Seleznev, S V
  • Publication Date: 1966

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Filing Info

  • Accession Number: 00014626
  • Record Type: Publication
  • Source Agency: Joint Publications Research Service
  • Report/Paper Numbers: Russian
  • Files: TRIS
  • Created Date: Aug 12 1971 12:00AM