Test Instruments Midterm
What is the maximum allowable resistance for test leads?
1 ohm
Voltage unbalance should not be more than what percent?
1-2%
Current unbalance should not be more than what percentage?
10%
What is the symbol for ohms?
Omega
20. Which part of an analog multimeter display is determined by the position of the range switch?
Scale
What unit is used to measure frequency?
hz
Is a programmable controller a linear or nonlinear load?
nonlinear
Which test instrument is used to detect noise in an electrical signal?
oscilloscope
What type of fluctuation is a voltage increase of 12% for 78 sec?
overvoltage
Would a quality control testing lab be more likely to use permanent or portable test instruments?
permanant
What type of fluctuation is a voltage decrease of 15% for 32 sec?
sag
Which harmonic is 180 Hz?
third
In-line ammeters are used to measure small amounts of current.
true
Which electrical property equals current multiplied by resistance?
voltage
What type of voltage test instrument does not require direct contact with the circuit?
voltage indicator
How many electrical degrees separate balanced phases?
120 degrees
Which test instrument is used to test phase unbalance?
3 phase power analyzer
How many seconds can a momentary power interruption last?
3 seconds
A 1% current unbalance can create an 8% voltage unbalance.
False
What color is standard for grounding conductors?
Green
Would a maintenance technician who troubleshoots production equipment be more likely to use permanent or portable test instruments?
Portable
18. Surface leakage current is current that flows from areas on conductors where insulation has been removed to allow for electrical connections.
True
A high CAT rating indicates that a test instrument can be used in a circuit with high power, great possibility of short circuits, and high energy transients.
True
Both the function switch and the connection of the test leads must match the desired measurement before testing a circuit.
True
What colors are standard for neutral conductors?
White and natural gray
Which type of ammeter is used when the circuit to be measured cannot be opened?
clamp on
Which test instrument is designed to measure temperature at a point without contact?
infrared thermometer
Is an incandescent lamp a linear or nonlinear load?
linear
What is the abbreviation for milliamperes?
mA
The measurement hold mode is a multimeter mode that captures and stores the lowest and highest measurements for later display.
min max
Which common multimeter mode would be most useful in recording high- or low- voltage conditions over a period of time?
min max
Improper phase sequence reverses motor rotation.
true
Which type of meter, analog or digital, is more likely to be affected by electrical noise?
Digital
Which type of meter, analog or digital, is more likely to warn the user if the function switch is improperly set?
Digital
Leather protector gloves are used to protect wearers from electrical shock.
False
Tagout physically prevents energy sources from being energized.
False
The caution signal word indicates an imminently hazardous situation that, if not avoided,results in death or serious injury.
False
Which two temperature scales are most commonly used by test instruments?
Farenheit/celsius
What unit is used to measure capacitance?
Farods
Which unit prefix indicates one million times the base unit?
Mega (M)
Which unit prefix indicates one thousandth of the base unit?
Milli
Which organization publishes the National Electrical Code®?
NFPA
19. Which type of AC voltage measurement is useful because it equates the heat produced by an AC sine wave to DC resistive circuit?
RMS
Digital meters are more popular than analog meters because digital meters typically have greater measuring capabilities.
True
Loads such as motors and solenoids decrease in resistance over time
True
Test instruments should be periodically tested for accuracy.
True
What electrical unit is used to rate rubber insulating gloves?
Voltage
What color is the test lead that typically indicates negative or ground?
black
Which multimeter test mode is commonly used to test components such as switches, uses, electrical connections, and individual conductors?
continuity
Which electrical property is measured to indicate total circuit loading?
current
What type of electronic component is tested by measuring the voltage drop across it in two directions?
diode
480 Hz is a triplen harmonic.
false
Harmonics are produced by linear loads.
false
High voltage unbalances can be created by small current unbalances.
false
What type of additional personal protective equipment must be worn when working around electrical systems with a risk of arc flash?
flash suit
Which common multimeter mode would be most useful in measuring the change in current when a load is turned ON?
relative
Which common multimeter mode records a mensurement and displays the difference between the reading and subsequent measurements?
relative mode
Nonlinear loads are a common source of harmonic problems.
true
Reverse the polarity of the test leads when a negative sign is displayed at the beginning of a multimeter bar graph.
true
Some motors can continue to operate on only two out of three phases.
true