1. Three identical transformers rated 2 KVA, 120/120 volts 60 hz.. The primaries are connected in delta and the secondaries are connected in wye. (a) Draw the circuit and (b) complete the table below for the rated values: Phase voltage Phase current Line voltage Line current Primary secondary

A single-phase l0-kVA,2300/230-volt,60-Hz two-winding distribution transformer is connected as an autotransformer to step up the voltage from 2300 to 2530 volts (a) Draw a schematic diagram of this arrangement, showing all voltages and currents when delivering full load at rated voltage. (b) Find the permissible kVA rating of the autotransformer if the winding currents and voltages are not to exceed the rated values as a two-winding transformer. How much of this kVA rating is transformed by magnetic induction? (C) The following data are obtained from tests carried out on the transformer when it is connected as a two-winding transformer: Open-circuit test with the low-voltage terminals excited: Applied voltage =230V, input current =0.45A, input power =70W. Short-circuit test with the high-voltage terminals excited: Applied voltage =120, input current =4.5A, input power =240W. Based on the data, compute the efficiency of the autotransformer corresponding to full load, rated voltage, and 0.8 power factor lagging. Comment on why the efficiency is higher as an autotransformer than as a two-winding transformer.

AC power of 100 volts and 1 ampere enters a transformer with 2 coils and exits the transformer with 20 coils. What is the exiting voltage and current?   a.) 1000v/0.1amp b.) 0.1v/1000amp   c.)1000v/1amp d.) 2v/20amp e.) No change

12.a. Comparing the transformer cores of core-form and shell-form transformers shows that thea. shell form provides lower reactance without increasing the transformer size.b. core form makes possible wider coils and better oil circulation.c. shell form is used exclusively in small low-voltage transformers.12.b. Distribution transformers are generally protected from damage due to excessive internal temperatures,by the operation of aA. lightning arrester.B. circuit breaker.C. surge diverter.