System Protection Technology

The objective of this module is to draw attention to the many factors that affect the accuracy of testing on protection circuits and equipment. Fundamental testing techniques are presented along with a discussion of the pitfalls to be avoided. A demonstration on the use of the oscilloscope is included. The need for specific safety precautions is also discussed.

On completion of this video and associated workbook, the participant should be able to understand the following concepts and apply them to day-to-day work activities:

• Types of electrical measurements
• Influence of instrument accuracy
• Effect of waveform (i.e. harmonics) on accuracy
• Effect of source impedance
• Effect of magnetic fields on digital instruments
• Current measurement, current probes
• Resistance measurement, ohmmeters
• Measuring DC resistance of inductive circuit
• Frequency measurement, counters, spectrum analyzer
• Selective voltmeter to measure signal strength
• Definition of frequency bandwidth
• Measuring dB signal strength
• dB logarithmic scale versus linear voltage scale
• The dB meter, “Terminated” or “Bridged” selection
• Operation of timers
• Phase angle measurement
• The oscilloscope operating principles
• Set-up and adjusting the scope
• Practical applications using the scope
• Precautions when using scope on ungrounded circuits
• Storage oscilloscopes
• Types of test set, traditional (analog) and advanced (digital)
• “Load box” (resistance), “Phantom load” (inductance)
• Three phase test set
• Out of phase sources; phase shifting transformer
• Solid state test set
• Need for safety when performing tests
• Clearance procedures
• Switchyard safety, isolation and grounding
• Potential hazards