Chapter 13 Power supply and Distribution
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) Extra-low voltage systems are defined as which of the following? 1) _______
A) Less than or equal to 24 volts.
B) Less than or equal to 36 volts.
C) Less than or equal to 50 volts.
2) What is the voltage limit for “low voltage” systems? 2) _______
A) 600 volts. B) 240 volts. C) 1000 volts.
3) What nominal system voltage is used in residential? 3) _______
A) 277/480 B) 120/240 C) 120/208
4) What voltages would you expect to find in a very large high-rise office building? Select all that
apply.
4) _______
A) 480 V B) 277 V C) 12,470 V
D) 120 V E) 240 V F) 208 V
5) Which of the following distribution systems would you select for a budget-conscious community
college campus?
5) _______
A) Distributed radial system. B) Primary and secondary loop system.
C) Primary selective system. D) Secondary loop system.
6) Which of the following distribution systems would you select for a medical research campus? 6) _______
A) Primary selective system. B) Distributed radial system.
C) Secondary loop system. D) Primary and secondary loop system.
7) To prevent destruction the event of a short circuit, protective devices (fuses or circuit breakers)
must have an interrupting capacity conforming to which of the following?
7) _______
A) 1.5 × the calculated short circuit current.
B) 30 times the rated ampacity of the device.
C) Greater than the calculated short circuit current.
8) What are functions of an uninterruptible power system (UPS)? Select all that apply. 8) _______
A) Allow time for a generator to start when there is a power outage.
B) Provide high quality power in terms of voltage and frequency.
C) Keep critical equipment running in the event of utility power outage.
D) Allow time to shut down in an orderly fashion.
9) The device in a PV system which allows the solar power to run AC appliances is which of the
following?
9) _______
A) Inverter. B) AC adapter. C) Rectifier. D) AC collector.
10) What are the good qualities achieved by using transformers with high K-ratings? Select all that
apply.
10)
______
A) Quieter operation. B) Less magnetic flux.
C)
Reduced I2R distribution losses. D) Reduced heat generation.
11) Variable frequency drives often take the place of motor starters, and can provide which of the
following functions? Select all that apply.
11)
______
A) Harmonics mitigation. B) On-off control.
C) Energy savings. D) Soft start.
12) Which of the following cable types in commonly used in residential construction? 12)
______
A) AC B) NM C) FC
13) Which of the following conductors has the largest diameter? 13)
______
A) 2/0 B) 8 C) 14
14) Which of the following electrical distribution systems would be most flexible for changes in a
high-tech office space?
14)
______
A) Cellular floor. B) Underfloor ducts. C) Access floor.
15) What is meant by “coordination” of fuses and circuit breakers? 15)
______
A) Capacity of devices are equal at different levels of the system.
B) Devices will not open upstream of the device which clears the fault.
C) Devices will clear to the main to prevent damage to the entire building.
