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Transformers ch 7

Power Generation and Distribution

QuestionAnswer
1. In North America, power is generated at a frequency of __. (25 Hz; 50Hz; 60 Hz; 120 Hz) 60 Hz
2. A __ is a device that indicates whether two AC sources to be connected in parallel are in the correct phase relationship(Alternator; Potentiometer; Rotor; Synchroscope) Synchroscope
3. The __ is the voltage measured line-to-line ( Line current; Line voltage; Winding current; Winding Voltage) Line voltage
4. The most efficient way to send electric power over transmission lines is at the lowest current possible. T/F True
5. The __ is the current flow through the individual windings. (Line current; Line voltage; Winding current; Winding voltage) Winding Current
6. A landfill generator runs on the methane gas created by decomposing trash. T/F True
7. The power in a single-phase circuit drops to zero __ every cycle. (Once; Twice; Three times; Four times) Twice
8. In an electric generating power plant, all generators must be connected in __ (Chain; Line; Parallel; Series) Parallel
9. The __ is the voltage measured across the windings (Line current; Line voltage; Winding current; Winding voltage) Winding voltage
10. A __ produces energy when a rotting coil cuts through magnetic flux ( Generator; Motor drive; Synchroscope; Transformer) Generator
11. The __ is the current flow through the lines to a load ( Line current; Line voltage; Phase current; Phase voltage) Line current
12. Describe the occurrences that resulted in the August 13th, 2003 East Coast power blackout. An overhead transmission line became overheated and sagged, shorting to ground when it came into contact with a tree.
13. A __ is a machine that converts mechanical energy into electrical energy by means of electromagnetic induction( Electrical transmitter; Generator; Motor drive; Transformer) Generator
14. What factors determine the amount of voltage produced by a generator? What is the relationship between the factors and the voltage? I. II and III (Number of Turns, Speed of Rotation of Rotor, Strength of magnetic field)
15. __is a method of synchronizing generators. (Chaining; Lights-out; Marking; Phase-timing) Lights-out
16. Utilities normally generate __ (Single-phase AC power; Single-phase DC power; 3-phase AC power; 3-phase DC power) 3-phase AC power
17. Magnetic force is used to rotate the coils in a generator. T/F False; prime mover
18. In the three-lights-out method, a lamp is connected as a load across each phase of the two sources, A to A, B to B, and C to C. T/F True
19. In the one-light-out method, phases are connected A to B, B to A, and C to C. T/F True
20. In a 3-phase circuit, power varies during a cycle but never falls to zero. T/F True
21. Transformers are usually used to step up voltage at the point of use. T/F False
22. If the line voltage is 480 V as shown in the illustration, the winding voltage is ___ V. page 99 workbook (120; 208; 240; 277) 277
23. How much power in kVA is delivered to a three-phase transformer when the line voltage applied is 480 volts and the line current is 12 amps 9.96 Kva
Created by: JoshHampton
 

 



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