GET WIRED! 202 Lesson 5 Quiz

14. When using an open delta with a center tapped transformer, one wire is the "high leg." The high leg is the one that ______. A. has the highest voltage measured to ground B. has the lowest voltage measured to ground C. has the most amperage D. is mounted highest on the panel

A. has the highest voltage measured to ground

1. A wye-delta transformer has its _____ connected as a wye and its _____ connected as a delta. A. secondary, primary B. primary, secondary

B. primary, secondary

7. A wye-delta transformer has a primary phase to phase voltage of 7200 V and a secondary phase to phase voltage of 480 V. What is the turns ratio? A. 8.66:1 B. 1:8.66 C. 1:15 D. 15:1

A. 8.66:1

8. A delta-wye transformer has a turns ratio of 9:1. The primary phase to phase voltage is 3600 V. What is the secondary phase to phase voltage? A. 32,400 V B. 692.8 V C. 230.94 V D. 400 V

B. 692.8 V

9. A wye-delta transformer has a turns ratio of 2:1. It has a secondary phase to phase voltage of 480 V. The secondary is connected to a wye-connected three-phase resistive load of 50 ohms in each phase. How much current flow is there in each load resistor? A. 9.6 A B. 4.8 A C. 2.77 A D. 5.54 A

D. 5.54 A

15. In an open delta with single-phase loads, the high leg must be identified by ____. A. using orange wire B. tagging with orange tape C. both a and b above D. either a or b above

D. either a or b above

6. A wye-connected secondary has a phase to ground voltage of 277.14 V. What is the phase to phase voltage? A. 160 V B. 277.14 V C. 480 V D. 554.28 V

C. 480 V

5. When connecting three transformers for three-phase use with a delta secondary, a voltage test should be done before closing the secondary. The correct voltage reading is______. A. the rated secondary voltage value B. twice the rated secondary voltage value C. zero volts D. the sum of the three transformer primaries

C. zero volts

10. A wye-delta transformer has a primary voltage of 7200 V and a secondary voltage of 360 V. What is the turns ratio? A. 1:20 B. 20:1 C. 1:11.55 D. 11.55:1

D. 11.55:1

3. If a single three-phase transformer of the proper ratings is not available, three singlephase transformers can be connected to do the job. When this is done, the connection is called a ______. A. three-phase bank B. wye-delta bank C. wye bank D. delta bank

A. three-phase bank

12. A wye-delta transformer has a secondary phase voltage of 480 V. A delta-connected resistive load has a resistance of 12 ohms in each leg. What is the current in each load leg? A. 13.33 A B. 40 A C. 23.1 A D. 69.28 A

B. 40 A

4. In three-phase transformer connections, the primary leads are labeled with the letter _____ and the secondary leads are labeled with the letter _____. A. X, H B. H, X C. L, X D. X, L

B. H, X

2. A delta-wye transformer has its _____ connected as a delta and its _____ connected as a wye. A. secondary, primary B. primary, secondary

B. primary, secondary

13. An open delta connection is made using _____ single-phase transformers. A. one B. two C. three D. four

B. two

11. A delta-delta transformer has a primary voltage of 7200 V and a secondary voltage of 360 V. What is the turns ratio? A. 11.55:1 B. 1:11.55 C. 20:1 D. 1:20

C. 20:1