Question

2. Figure 5 depicts how power is distributed from the power company to their customers through a combination of two transformers and a transmission line The transmission line is shown to have a resistance equal to 22. N, and N2 represent the number of turns on the primary or the secondary of the two transformers. İp is the current provided by the power company iis the current through the transmission line The power company provides 120v, 60 Hz to the primary side of the first transformer The customer receives 20 amps from the secondary of the second transformer . itl N1:N2 N2:N1 20 A Power 120V Vb oCstomer Figure 5: Power company distribution system Fill in the following table for each of the different values provided for NJN2, where Pin-120-ip, Po-vo-20 and η=(PJP,n)-100 is the efficiency in getting power from the power company to the customer N/N Amps Amps Volts Volts Volts Watts Watts 1/10 1/100 1/1000 a) What happens to the efficiency as N1/N2gets smaller? b) When N1/N2-1 the voltages on the primary and secondary of each transformer are equal. In this case the transformers could just be replaced with wires at the top and bottom of each transformer. That makes this circumstance equivalent to what could be done in a DC system. How does the efficiency of the DC system, where N,/N2 -1, compare to the efficiency of the other circumstances where N1/N2 < 1? In each case, P-Pin-where does the power that doesn't get to the customer go? What would happen to the efficiency if N1/N2 became smaller still? What happens to the voltage Vo as N/N2 becomes smaller? Is that good or bad? Why? c) d) e)

Answer 1