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A capacitor-type stored-energy welder is to deliver the same heat to a single weld as a conventional welder that draws 20 kVA at 0.8 pf for 0.0625 second/weld. If C = 2000 μF, find the voltage to which it is charged. |
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Answer» The energy supplied per weld in a conventional welder is W = VA × cos φ× time = 20,000 × 0.8 × 0.0625 = 1000 J Now, energy stored in a capacitor is (1/2) CV2 ∴ W = 1/2CV2 or V = √(2W/C) = √((2 x 1000)/(2000 x 10-6)) = 1000V |
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