Digital Multimeter Functions Flashcards
Witch DMM function is used to measure resistance
Ohmmeter
Which DMM function is used to measure current flow in an electrical circuit ?
Ammeter
What is the impedance value or most digital voltmeters
10 megohms
Which meters are more commonly used in electrical trade
Digital
Which meters are more accurate analog or digital
Digital
What is the abbreviation DMM short for
Digital multimeter
Which meter is used to take current measurements without opening the circuit
Clamp on ammeters
What is meter loading
The effect a meter has on a circuit
(Due to the meter changing the circuit by lowering the total resistance)
Witch lowers the voltage to
When working with electronic ballast, VSD or computer what do you use (true RMS) or (average responding DDM?)
You use true RMS because these items have non sinusoidal wave forms
Witch DMM setting would be used to measure the out put of an
Alternator_______
Rectifier_________
Alternator = AC volts
Rectifier = DC volts
List to advantage of a clamp on ammiter
Over a DMM
They have a higher amperage rating
You don’t have to open the circuit
Witch meter function would be selected to provide quick and easy testing of weather a fuse is open or has a complete path through it
Continuity
DMM amperage rating is what
10 amps
List three causes of insulation deterioration
1, Mechanical damage
2, Heat
3, Oil
List two applications where maggers are used
Routine checks
Checking wires in conduit
List three types of electrical equipment that could have their insulation resistance tested
1, cables
2, motors
3, transformers
What should always be done with a conductor before and after megger testing the conductor
1, Turn off power
2, discharge
What is the minimum reading expected when meggering a motor conductor
1 megohm or higher
What CSA standard covers workplace electrical safety
CSA standard Z462-08
What category of DMM is required for testing where fault current are very high
Category IV
The category rating of Test leads of a DMM must meet or exceeded the category rating of the DMM
True or false
True
What must be done before using a DMM
Test on a known circuit to ensure that the DMM is working properly 
Once you are finished using a DMM, you can throw it in to your toolbox
True or false
False
Metre tests leads can be replaced with the cheapest leads available
True or false
False
If a metre fuse is blown, it can be replaced with any fuse
True or false
False
Ideal metres must be stored in a dark room
True or false
False
Must be in a tempture controlled area
What is the window on the DMM called where the reading appears
Display
The bar graph has a polarity indicator on the left
True or false
True
Identify one cause of false readings on a DMM on a de energize circuit
Capacitive coupling
False readings are normally none as
Ghost or stray voltage
What must be done to get an accurate rating of OL appears on a display when the DMM is on manual range
Switch to a higher range
The bar graph on a DMM reacts like the needle on an analogue metre
True or false
True
How does an analog meter work
It draws current from the circuit being measured to deflect the coil and pointer of the meter movement.
The amount of current drawn dippends on the ohms per volt of the meter
How do digital meters work
They use an analogy / to / digital converter to display a reading
Which feature on a DMM would best be used to detect rapidly changing signal such as contact contact or micro switch
Bar graph
