Test 8

Question 1

DC power may be constant or variable but always maintains one direction.

Answer 1

True

Question 2

In terms of power quality, a square wave is a substantial improvement over a modified square wave.

Answer 2

False

Question 3

Three-phase AC power is commonly used for motors because they can be more efficient and smaller than single-phase motors of the same power output.

Answer 3

True

Question 4

Total harmonic distortion (THD) is the ratio of the sum of all harmonic components in a waveform to the fundamental frequency component.

Answer 4

True

Question 5

A reactive load is a load that keeps voltage and current waveforms in phase.

Answer 5

False

Question 6

An inverter is a device that converts DC power to AC power.

Answer 6

True

Question 7

Thyristors can only be completely ON or completely OFF.

Answer 7

True

Question 8

Pulse-width modulation (PWM) is a method of simulating waveforms by switching series device ON and OFF at high frequency and for variable lengths of time.

Answer 8

True

Question 9

At high temperatures, an inverter may force the array from maximum power to a higher operating voltage, reducing power and current levels.

Answer 9

True

Question 10

Interconnection standards require interactive inverters to maintain an output power factor between 0.95 leading and 0.95 lagging.

Answer 10

True

Question 11

____ is the shape of an electrical signal that varies over time.

Answer 11

waveform

Question 12

A(n) ____ wave is an alternating current waveform current waveform that switches between maximum positive and negative values every half period.

Answer 12

square

Question 13

____ is the number of waveform cycles in one second.

Answer 13

Frequency

Question 14

____ is the measure of how closely the power on an electrical circuit matches the nominal values for parameters such as voltage, current, harmonics, and power factor.

Answer 14

Power quality

Question 15

____ are temporary undesirable voltages in an electrical circuit, ranging from a few volts to several thousand volts and lasting from a few microseconds up to a few milliseconds.

Answer 15

Transient voltages

Question 16

Phase unbalance is the unbalance that occurs when three-phase power lines are more or less than ____° out of phase.

Answer 16

120

Question 17

A(n) ____ module is a PV module that outputs AC power through an inverter attached in place of the normal DC junction box.

Answer 17

AC

Question 18

A(n) _____-commutated inverter is an inverter that can internally control the activation and duration of its switching.

Answer 18

self

Question 19

A(n) ____ is a device that transfers energy from one circuit to another through magnetic coupling.

Answer 19

transformer

Question 20

____ are the power required to operate inverter electronics and keep the inverter in a powered state

Answer 20

Stand-by losses

Question 21

A(n) ____ is the interval of time between the beginnings of each waveform pattern.

Answer 21

cycle

Question 22

The ____ value is a statistical parameter representing the effective value of a waveform

Answer 22

root-mean-square RMS

Question 23

____ perform one or more power processing and control functions in addition to inverting.

Answer 23

Power conditioning units PCU’s

Question 24

A(n) ____ is a waveform component at an integer multiple of the fundamental waveform frequency.

Answer 24

harmonic

Question 25

____ power is a combination of true and reactive power and is given in units of volt-amperes (VA).

Answer 25

Apparent

Question 26

A(n) ____ inverter is an inverter whose switching devices are triggered by an external source.

Answer 26

line-commutated

Question 27

A(n) _____ inverter circuit is a circuit that switches DC input into square wave AC output by using two pairs of switching devices.

Answer 27

H-bridge

Question 28

A(n) ____ inverters circuit is a circuit that switches DC input into AC output by using one pair of switching devices and a center-tapped transformer.

Answer 28

push-pull

Question 29

A(n) ____ is a device that converts AC power to DC power.

Answer 29

rectifier

Question 30

A(n) ____ is a device that changes DC power form one voltage to another.

Answer 30

DC-DC converter