file 02213 15 Question 30 Are the transformers connecting power plant

# File 02213 15 question 30 are the transformers

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file 02213 15
Question 30 Are the transformers connecting power plant generators to high-voltage power lines considered step-up or step-down ? Explain your answer. file 02214 Question 31 In each of these circuits, calculate the amount of load impedance ”seen” by the voltage sources given the turns ratio of each transformer: 30 1:1 30 120 VAC 240 VAC 1:2 Z load = ??? Z load = ??? Hint: ”impedance” ( Z ) is defined mathematically as the ratio of voltage ( E ) to current ( I ). file 00659 16
Answer 7 Fluorescent lamp: P = 60 W ; Q = 54.3 VAR ; S = 80.9 VA ; PF = 0.74, leading Incandescent lamp: P = 60 W ; Q = 0 VAR ; S = 60 VA ; PF = 1.0 Induction motor: P = 52.0 W ; Q = 20.4 VAR ; S = 55.8 VA ; PF = 0.93, lagging Answer 8 The beer itself is ”true” power ( P , measured in Watts). Good beer, good. Ideally, we’d like to have a full mug of beer (true power). Unfortunately, we also have foam in the mug, representing ”reactive” power ( Q , measured in Volt-Amps-Reactive), which does nothing but occupy space in the mug. Bad foam, bad. Together, their combined volume constitutes the ”apparent” power in the system ( S , measured in Volt-Amps). Follow-up question: can you think of any potential safety hazards that low power factor may present in a high-power circuit? We’re talking AC power circuits here, not beer!

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