Electrical power moves through a conductor when opposing dc or ac voltages are applied at opposite ends. Charge carriers — free electrons or electron holes in semiconductors, ions in electrolytes – migrate toward the opposite poles. Metals, with abundant free electrons, have high conductivity. All conductors are partial insulators and all insulators are, to some […]
Cathode ray tube vs. flat screen displays in oscilloscopes
Prior to the digital revolution in electronic instrumentation, oscilloscopes displayed waveforms on cathode ray tube screens. Modern digital oscilloscopes universally have flat screens. The flat screen is light, thin, consumes far less energy, and is less expensive to manufacture. All agree that it is a great improvement. The one advantage of CRT technology is that […]
Mitigating ac motor-shaft voltage and bearing currents
Bearing problems are the greatest single contributing factor in motor failure. Often motor damage happens before bearing wear is noticeable. To avoid expensive repairs and costly downtime, early detection is essential. Proper installation of replacement bearings and correct lubrication are critical. It is well known that insufficient lubrication brings early bearing failure, but many maintenance […]
The difference between metal conductors and waveguides
Manufacturers of instrumentation are striving to satisfy the demands of modern electronics which continuously require greater bandwidth. There has been a growing tendancy to incorporate waveguides, ranging from extremely small units soldered into printed circuits, to larger devices mounted in enclosures. The natural question that arises is how waveguides differ from ordinary wiring, and why […]
The difference between histograms and spectrograms
Despite their similar names, histograms and spectrograms are totally different ways of displaying a signal or function in a digital storage oscilloscope (DSO). Both are useful in organizing and analyzing electrical waveforms, but the type of information that is displayed and the conclusions that may be drawn from them are worlds apart. Histograms and spectrograms […]
Difference between synchronous and asynchronous (induction) motors
All rotary electric motors, ac and dc, operate because of the interaction of two magnetic fields. One is stationary and is (usually) associated with the motor’s outer enclosure. The other rotates and is associated with the motor’s spinning armature (also called its rotor). These two fields are created by interactions between magnetic fields. In a […]
Waveform settings vs. output settings in Tektronix MDO3000 oscilloscope
Most digital storage oscilloscopes include an internal arbitrary function generator (AFG). In the Tektronix MDO3000 instrument, there is a port on the back panel labeled AFG Out. To control the AFG and display its output, connect a BNC cable to this port and plug the other end into one of the analog channel inputs or […]
Exploring the difference between a digital oscilloscope and a spectrum analyzer
Traditionally, only the spectrum analyzer was capable of displaying electrical and electromagnetic signals in the frequency domain and the oscilloscope took control of the time domain. More recently, each instrument has become competent in the other’s territory. But this overlapping tendency is far from absolute. Oscilloscopes, working in the Math>FFT mode, have always had a […]
Analog and digital modulation and modulation measurements
In amplitude modulation (AM), the amplitude of a carrier wave whose frequency remains constant changes in response to the modulating signal. In frequency modulation (FM), it is the frequency of the carrier that varies with the amplitude of the modulating signal. The carrier frequency deviates more when the modulating signal amplitude is higher. There are […]
Three-phase testing basics – Mitigating harmonic current
An electrical conductor warms up when it conveys current. If the heat is high enough the conductor can be damaged, so it is beneficial to limit current flow. Three-phase electrical distribution systems are highly effective in limiting current flow without reducing the amount of power delivered to the load. They do this by separating phases […]
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