Power Quality Test Review

Question 1

While IT devices can be made more efficient, business’s ever-growing reliance on IT still results in a net ? in the use of electrical power.

Answer 1

Increase

Question 2

Kirchhoff’s Current Law, Kirchhoff’s Voltage law, Ohms law are the main laws/formulas used to solve PQ problems.

Answer 2

Not Thevenins

Question 3

Harmonic currents are induced by loads that draw current in a(n) ? Waveform.

Answer 3

Distorted

Question 4

Voltage Phasors, or Vectors are separated by ? degrees in a normal 3-phase power distribution system

Answer 4

120

Question 5

A ? is a decrease from the nominal voltage supply level

Answer 5

Sag

Question 6

A ? is an increase in the voltage level.

Answer 6

Swell

Question 7

? are frequently the result of a sudden decrease in load current.

Answer 7

Swells

Question 8

A ? is one who is familiar with the construction and operation of the equipment and the hazards involved.

Answer 8

Qualified Person

Question 9

NIOSH identified five scenarios that describe the incidents resulting in 244 fatalities. Of the five scenarios, direct worker contact with energized equipment accounted for ? percent.

Answer 9

21

Question 10

The use of proper personal protective equipment is intended to ? injury

Answer 10

Prevent and Reduce

Question 11

? accounts for 24% of electrical activities being performed at the time of an accident that resulted in injuries.

Answer 11

Troubleshooting

Question 12

According to NFPA 70B, “As a general rule, no electrical apparatus should be worked on while it is ?.

Answer 12

Energized

Question 13

A 3% voltage imbalance between phases may result in the need to de-rate electric motors by ? percent?

Answer 13

10

Question 14

Both Voltage unbalance and harmonics are generally considered as ? power quality problems

Answer 14

Steady-State

Question 15

Permanently-installed power quality monitoring systems are typically ? and provide the advantage of showing trends.

Answer 15

Web-Based

Question 16

The ? is one of the most popular tools for the PQ monitoring because it does not require contact with energized circuits

Answer 16

Infrared Imager

Question 17

A power quality instrument should be rated for the ? range of voltage and current levels.

Answer 17

Anticipated

Question 18

When accurate measurements are needed on sinusoidal waveforms to detect distortions, only ? meters should be used.

Answer 18

TRUE RMS

Question 19

If PW measurements require potential transformers (PT’s) to step down voltages, make sure that the ? that the PT’s will pass through will not affect the reading.

Answer 19

bandwidth signals and frequency response

Make sure you have the right equipment for the right thing

Question 20

Volt-amperes=reactives(VARS), should only be computed on the ? in a distorted or unbalanced system

Answer 20

fundamental frequency components

Question 21

Sub-quarter-cycle changes in the waveshape that usually do not trigger abn RMS variation define ?.

Answer 21

Transients

Question 22

If the cumulative probability (CP) value obtained from an analysis study continues to increase, what results can be expected?

Answer 22

Mis-operating equipment, overheating motors, overheating transformers

Question 23

What is the likely direction or source of the fault condition if the current increases significantly when the voltage decreases?

Answer 23

Downstream toward the load

Question 24

When measuring equipment efficiency, monitoring should be conducted over the ?, because the efficiency varies as a function of load.

Answer 24

full range of loading

Question 25

The potential difference in two improperly-made ground connections causes current to flow in a ground loop path, with possible noise and/or component failures.

Answer 25

TRUE

Question 26

Telecommunications circuits are susceptible to harmonic currents being coupled or induced into the telecom siring.

Answer 26

TRUE

Question 27

n order to prevent premature failure, a motor should be de-rated due to which findings?

Answer 27

Harmonic losses, Negative sequence values, Voltage unbalance levels

Question 28

If electrical disturbances are recorded over an extended period and the monitoring equipment indicates they are on the utility side of the PCC, what should be done to remedy the disturbances

Answer 28

The Utility should be informed of the monitored events

Question 29

Lightning is a ?.

Answer 29

high frequency transient

Question 30

Improperly grounded communication cables between peripherals and the mainframe computer may become a problem when exposed to strong level RF signals though

Answer 30

EMF coupling, inductance, inductive coupling

Question 31

Well-grounded, properly-sized UL listed ? should be installed on any metallic interface that extends outside a structure, including the incoming electric service, phone lines, and any exterior branch circuits.

Answer 31

surge protection

Question 32

(WYSIWYG) is NOT one of the tested and verifiable “Rules of Thumb”

Answer 32

(What you see is what you get)

Question 33

On a single-phase circuit, the origin of a voltage sag is usually ? significantly during the sag

Answer 33

downstream if the neutral-to-ground voltage increased

Question 34

Sag is the sum of the ? in both the line (hot) and neutral (grounded) wires.

Answer 34

Voltage drops

Question 35

What type power apply will have a sharp reduction in current at the beginning of a sag, followed by an increase in current to a value greater than the original current level, until the sag has ended or the equipment trips offline.

Answer 35

A single-phase, rectified-input, switching power supply.

Question 36

A load or circuit with significant loads with rectified inputs will most likely have a true power factor less than the displacement power factor.

Answer 36

TRUE

Question 37

A common source of incorrect data comes from not using current probes within their ratings

Answer 37

TRUE

Question 38

Negative transients add to energy from the voltage sine wave

Answer 38

FALSE

Question 39

Learning which mitigation solutions will work for which power quality (PQ) phenomena can be studied from the phenomena side or the solution side.

Answer 39

TRUE

Question 40

-Which of the following is NOT a classification for PQ phenomena?

Answer 40

Induction