A transformer is mounted on a utility pole. The distribution line brings in powe

Question

A transformer is mounted on a utility pole. The distribution line brings in power with VRMS= 8.5kV from a substation. The transformer services houses that use VRMS = 120V. The houses serviced use an average of 78kW. Assume the loads to be purely resistive and the transformer to be 100% efficient. a) Is this a 'step up' or 'step down' transformer? b) Calculate the ratio of the number turns on the substation side to the house side. c) Calculate the peak current on the house side and on the substation side. d) What Is the load on the house side? e) How large is the load as 'seen' by the substation?

Explanation / Answer

a) Step down.

Beacuse, V_output < V_input

b)N1/N2 = Vin/Vout

= 8500/120

= 70.83

c)Average power = Irms*Vrms

Irms = Power/Vrms

= 78000/120

= 650 A

Ipeak = sqrt(2)*Irms

= 1.414*650

= 919.24 A

d)R = Vrms/Irms

= 120/650

= 0.1846 ohm

e) Pin = Vrms^2/Rin

Rin = Vrms^2/Pin

= 8500^2/78000

= 926.3 ohm

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.