Electrical Measuring Instruments/ Troubleshooting Flashcards
Voltage, resistance and power all relate to:
The flow of current
The definition of full-scale current
The amount of current that must flow through a meter coil to cause a full scale deflection
Define: Meter sensitivity
Reciprocal value of [full scale current], represents total amount of resistance for each volt needed to provide full scale current
The amount of current required to give a full deflection on a meter is dependent on
scale that the meter is set to
A meter that requires 1 milliamp of current to provide full scale deflection requires ____ ohms or resistance
1,000 ohms
The function of the meter sensitivity resistance
Limits the current through the meter to the [full scale current]
The total resistance of a meter is termed
meter resistance
If the range of current to be measured is greater than the full scale current of a meter, what is installed and how is it installed?
Shunt, installed in parallel
Basic description of a shunt installed in parallel to a meter
A resistor which increases the amount of current the meter can measure
The type of ohmmeter used to measure very low resistances such as magneto coils
shunt-type ohmeter
The basic operation of a Megohmeter (megger)
Hand cranked generator allows the megger to produce several hundred volts
Multimeter resolution reffers to
How small a measurement the meter can make
Digital multimeters display the _____ of AC voltage waves
RMS values (equivalent DC value)
2 things the continuity function on a multi-meter can be used to detect
- Distinguish good/bad fuses
2. Distinguish good/bad switches
What is considered to be zero reference for voltage during troubleshooting ?
Ground
When a voltmeter is placed across an open component in a series circuit, what the multimeter reads
Battery or applied voltage
The 3 RULES to apply to troubleshooting circuits
- Make a measurement ONLY if you know what the good measurement will be
- Make as few measurements as possible
- Select the best tool for the job at hand
The measuring device that does not require the circuit to be opened in order to take a current reading
Current probe
Measuring voltage across an open component in a series circuit reads
Supply/source voltage
Measuring voltage across all other components in a series circuit except the defective component reads
zero
Measuring voltage across a shorted component in a series circuit reads
zero
Measuring voltage across an all other components in a series circuit other than the shorted component reads
higher than normal voltage
Measuring voltage across all branches of a parallel circuit in a short reads
zero
Measuring voltage across all branches of a parallel circuit if one branch is open reads
Source/supply
Measuring resistance across an open component reads
Infinite
The first step in troubleshooting using an ohmeter
ISOLATE the component
