402 ELEMENTS OF ELECTRICAL ENGINEERING. 



113. A lo-kilowatt 1,100 : I lo-volt transformer is connected 

 as an auto transformer to step up from 1,100 volts to 1,210 volts. 

 (a) Find the amount of power that can be delivered to a non- 

 inductive receiving circuit at 1,210 volts without exceeding the 

 rating of the transformer ; (fr) find the current in each coil of the 

 transformer ; and (c) specify the amount of power delivered to or 

 delivered by each coil. 



114. A lo-kilowatt 1,100 : I lO-volt transformer is connected 

 as an autotransformer to step down from 1,100 volts to 990 volts. 

 Find (a) the amount of power that can be delivered to a non- 

 inductive receiving circuit at 990 volts without exceeding the 

 rating of the transformer ; (b) find the current in each coil of the 

 transformer ; and (c) specify the amount of power delivered to 

 or by each coil. 



H5a. A transformer has two coils AB and CD arranged as 

 shown in Fig. 115^. The coil AB is connected to no-volt 

 mains, point A being connected to main number one, and point 

 B being connected to main number two. Specify the exact 

 manner in which the coil CD must be connected in order that 

 auto-step-up transformation may be accomplished and find the 

 value of the voltage across the service mains. 



Fig. 115A 



Specify the exact manner in which the coil CD, Fig. 

 1 1 5/>, must be connected in order that auto-step-down transfor- 

 mation may be accomplished, with the coil AB connected to 

 iio-volt supply mains, and find the value of the voltage across 

 the service mains. 



H5c. The service mains in problem 115^ deliver current to a 

 non-inductive receiving circuit of which the resistance is 2 ohms. 

 Find (a) the current and power delivered to the receiving circuit; 

 (b) the power developed in coil CD (specify whether this coil 



