Deck 7: Power Supplies, Batteries, and Emergency Systems

Question 1

A capacitor is used to remove unwanted ripple from the output of a rectifier and will maintain a constant voltage regulation.

Answer 1

False

Question 2

A primary protector is used to protect the main system from higher voltage lightning strikes or switching transients on the input side of the power line.

Answer 2

True

Question 3

According to the National Electrical Code, all boxes and enclosures containing emergency systems must be clearly and permanently marked to indicate the presence of emergency circuits or systems.

Answer 3

True

Question 4

In a half-wave rectifier, the diode conducts ________.

A) For the entire input signal
B) For only 90 degrees of the input signal
C) For only 180 degrees of the input signal
D) For only 270 degrees of the input signal

Question 5

According to the National Electrical Code, After a main power failure, the activation of an emergency system must take place within ________.

A) 10 seconds
B) 30 seconds
C) 45 seconds
D) 1 minute

Question 6

When transporting power over long distances, DC remains the best choice.

Question 7

A switch mode power supply is considered to be ________.

A) Linear
B) Nonlinear
C) Regulated
D) Less efficient than most other types of power supplies

Question 8

What is the purpose of an Uninterruptible Power Supply (UPS)?

A) Provides AC regulation
B) Provide steady-state power during a total failure of the main supply input
C) Provide filtering
D) All the above

Question 9

An example of a primary protector is _________.

A) A UPS
B) A fuse
C) A lightning arrestor
D) A harmonic filter

Question 10

The "hot" power line is staked at a permanent ground reference by the power company.

Question 11

Motor-driven generators are able to provide DC-to-AC conversion.

Question 12

A 1:1 relation exists between the primary and the secondary coils of the isolation transformer.

Question 13

According to the National Electrical Code, storage batteries and UPS's must be able to supply maximum load capacity for _______.

A) Not less than 1 minute
B) Not less than 30 minutes
C) Not less than 1 hour
D) Not less than 1.5 hours

Question 14

Which type of battery is not rechargeable?

A) Primary Cell
B) Secondary Cell
C) Minor Cell
D) Series-connected cell

Question 15

The secondary of an isolation transformer is usually grounded.

Question 16

A rectifier converts AC into pulsating DC.

Question 17

What component is used as a voltage regulator?

A) A capacitor
B) A zener diode
C) A varistor
D) A series-resistor

Question 18

According to the National Electrical Code, the AHJ must personally conduct or witness an emergency system test and verify its functionality in writing before using the system.

Question 19

The typical input frequency of a power supply is _______.

A) 60Hz
B) 100Hz
C) 120Hz
D) 300Hz

Question 20

What is the ripple percentage of a typical unfiltered full-wave rectifier?

A) 121%
B) 100%
C) 50%
D) 48%

Question 21

According to the National Electrical Code, who is responsible for approving the periodic schedule for testing and maintaining an emergency system?

Question 22

Which type of battery needs to be fully discharged before recharging can take place?

Question 23

List three differences between half-wave and full-wave/bridge rectifiers.

Question 24

If the input frequency of a half-wave rectifier is 60Hz, what will be the output frequency?

Question 25

What type of device is used to limit peak voltage surges, while diverting power surges and transients to ground?

Question 26

Give an example of a primary protector.

Question 27

For what application is an engine-driven AC generator typically used?

Question 28

What type of transformer has a single winding with an adjustable center tap?

Question 29

How can a technician float themselves and safely remove the risk for shock from the hot line?

Question 30

If the voltage on the primary of an isolation transformer is 48V, the voltage on the secondary will be _________.