The Electrical Measuring Instruments electrical training course covers the maintenance procedures and principles on which electrical test instruments operate. Basic instruments covered in this online course include voltmeter, ammeter, wattmeter, ohmmeter, and megohmmeter. Covers AC metering, split-core ammeter, use of current and potential transformers. Includes detailed coverage of modern multimeters. Explains functions and uses of oscilloscopes. This course has no prerequisites. Electrical Measuring Instruments is available in online technical training and course manual formats.
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Lesson 1 - Principles of Meter Operation
Digital meter design; Integrated ADCs; Displays; Introduction to analog meters; D'Arsonval movement; Magnetic shielding; Parallax error; Accuracy
– Define the terms digital meter and analog meter.– Describe the purpose of the analog-to-digital converter in a digital meter.– Identify and label graphs of integrator output from a dual-slope integrating meter.– Explain how time is related to voltage measurement in an integrating digital meter.– Differentiate among the terms accuracy, sensitivity, and resolution.– Explain how a D'Arsonval meter movement works.– Describe the parallax effect, and explain how to avoid it when using an analog meter.– State the sensitivity formula for an analog meter.
Lesson 2 - Ammeters, Voltmeters, and Wattmeters
Measurement considerations; Measuring direct current; Multirange ammeters; Measuring alternating current; Voltmeters; Wattmeters
– Describe the differences and similarities between an analog ammeter and a voltmeter.– Explain how ammeters and voltmeters are protected internally from overcurrent.– Explain how a make-then-break switch works.– Identify which meters should be connected in series in a circuit and which should be connected in parallel.– Describe how an analog wattmeter works.– Explain how it is possible to overload a wattmeter, even with the meter's pointer at less than full-scale deflection.
Lesson 3 - Resistance Measurement
Measuring resistance with an ohmmeter; Checking and calibrating an ohmmeter; Shunt ohmmeters; Megohmmeters
– Characteristic differences between a series ohmmeter and a shunt ohmmeter.– Explain why ohmmeter scales read from right to left, instead of left to right, and why they are nonlinear.– Describe the internal circuits and basic operation of an opposed-coil megohmmeter.– State the primary safety precaution to take when using an ohmmeter.– Describe two methods used by ohmmeter manufacturers to extend the range of their instruments.– Explain how to test for opens, shorts, and grounds, using a megohmmeter.– Describe how to make zero-adjustments on ohmmeters and megohmmeters.– Explain why variable resistors are needed in battery-powered ohmmeters.
Lesson 4 - Multimeters
Graphical DMM; Advanced meter functions; Multimeter accessories and safety
– Demonstrate how to measure ac and dc current and voltage with a multimeter.– Describe the function of a current probe.
– Explain how to isolate the source of a glitch with a graphical multimeter.
– Demonstrate how to read the screen display of a graphical multimeter in the Trend mode.
– Explain why you set a meter to its highest range before taking your first measurement.
– Define autoranging and auto-polarity.
– List three safety precautions to take when using multimeters.
Lesson 5 - Oscilloscopes
Kinds of oscilloscopes; Triggering; Digital oscilloscopes; Dual-trace oscilloscopes; Controls; Probes; Oscilloscopes in troubleshooting
– Describe how an analog oscilloscope works.– Describe advantages of a digital oscilloscope over an analog oscilloscope.– Demonstrate how to measure voltage with an oscilloscope.– Show two methods of determining phase angles with an oscilloscope.