Analog Meters Flashcards
Where is the zero adjust screw on a meter
Front
If there is no off switch where should you store the meter
At the highest AC volts setting
The purpose for a reset button on the multimeters is
Reset the internal circuit breaker
The function of the 0 ohms just knob is for
Compensate for voltage variations in the internal battery
The current for full-scale deflection in meter movement rarely exceeds
50 mA
What indication will result with a break in the test lead of any voltage tester
0 V
Neon type testers usually not used on circuits less than
90 V
What type of tester will identify specific wiring faults on 120 V branch receptacles
Outlet tester
When a solenoid and plunger voltage tester is connected to a voltage source on what does the position of the indicating disk depend
Strength of field which is proportionate to voltage
What neon signal identifies that the voltage under test is DC
Only one neon lamp lights up
If a voltage tester disc vibrates
An AC voltage is being tested
Which category of voltages is the solenoid and plunger tester ideal for
Nominal voltages
How long can a solenoid and plunger tester be connected to voltage
20 seconds
What is the maximum nominal voltage value of the solenoid and plunger voltage tester can be used on
600 V
A voltmeter sensitivity and the solenoid and plunger voltage tester sensitivity
Are the same
Voltmeters are connected in
Parallel
What do you do before testing a dc voltage?
Check leads have correct polarity.
Why keep meters dry and clean
So to not cause flashover
Meter leads that are damaged
Should be replaced
Why can testing a battery be a safety hazard
Cause short circuit and explode
How is a shunt connected in relation to the galvanometer?
Parallel
Shunt device has a very what resistance?
Low
Why are shunts made of materials with low temp coefficient?
Ensure minimal resistance change
Full scale deflection current in a meter movement can be as low as
5 micro amps
Why do you have a make before break switch in ammeter?
Prevent excess current flow in movement
Full scale current ratings in ammeter vary from
5 micro amps to 50 milliamps
Better sensitivity is
A lower amp rating
What kind of circuit is most affected by using an ammeter with poor sensitivity?
Love voltage/low power
Ideal theoretical resistance of ammeter is
Zero
Why not use larger shunts in the meter
Too big
Too much heat
Manganin has
Low temp coefficient
Ac clamp ammeter uses the principle of
Transformer
Conductor of 2.2A is looped four times the scale should be
2.2x4=8.8
Disadvantage of tong tester
Only one range
Shunt resistor
Low mid scale
Ohm meters all have what kind of scales
Non-linear
2 types of ohm meters
Series
Shunt
Series ohm meter high resistance values on the
Left
In the shunt ohm meter the high resistance values are on the
Right
What ohm meter used for low resistance?
Shunt
Disadvantages of shunt ohm meter
Power discharges as soon as meter is turned on
What ohm meter in multimeter?
Series
What function rheostat in ohm meter
Compensate for battery
Never connect an ohm meter to
A live circuit
2 uses for ohm meter
Continuity
Resistance
Infinity reading on an ohm meter means
Open circuit
If the ohm meter leads are separate you will get a reading of
Infinity
If the ohm meter leads are touching you will get a
Zero reading
Megger is used for testing
High resistance
Insulation resistance
Typical Megger output
100-1000V
3 things when connecting ohm meter
Make sure not energized
Zero meter
Isolate at least one side
Why does polarity of the leads of a multimeter reverse when used for resistance?
Meter changes from a load to a supply
When testing capacitors
Discharge them
Precautions with a Megger
Don’t connect to energized circuit
Don’t use in low voltage circuits
Charges can be built up in Megger
