Rectification generates harmonic voltages and currents that can cause problems, e.g. insulation failures due to overheating and overvoltages, malfunction of solid-state equipment, communication interference, etc. The common addition of power factor correction capacitors to such a system generally increases the likelihood of such problems occurring. Online data acquisition and analysis of the harmonic content of system voltages and currents may be necessary to identify the cause properly and recommend a solution. In response to these problems, a field-proven portable harmonic-measurement/analysis system is described, as well as the advantages and versatility inherent in its use. This portable, computer-based system provides on-site data collection, precise harmonic identification via a fast Fourier transform, data analysis, and report preparation via a custom spreadsheet. Specific examples involving the application of this measurement/analysis system in the cement, steel, and carbon industries are presented. >

Harmonics-causes, effects, measurements and analysis-update

A method is discussed for on-line measurements of parameters of a power distribution system and its associated load. Four parameters are measured: the complex impedances of the distribution system and the load for harmonic frequencies; the complex rms (crms) values J/sub n/ of the harmonics of the load current j and the crms values E/sub n/ of the harmonics of the distribution system voltage e. The measurements are performed on two states of the system before and after it is disturbed by either connecting to it a capacitor or a harmonic generating device. The results of physical measurements are compared with those calculated from a model.

On-line measurement of equivalent parameters for harmonic frequencies of a power distribution system and load

An on-line measurement of equivalent parameters of a distribution
system and a harmonic generating load is discussed in the paper. Four
parameters are the subjects of the measurement: the distribution system
and the load complex impedances, the complex rms (crms) values J n
 of the load generated current j harmonics and the crms values E
 n of the distribution system internal voltage e harmonics.
The method discussed is based on measurements performed in two states of
the system, before and after disturbing it by a capacitor or by a
harmonic generating device. The effects of the random and systematic
measurement errors on the calculation accuracy are discussed in the
paper. The results are illustrated with computer modeling and with
physical measurements

On-line measurement of equivalent parameters of distribution system and its load for harmonic frequencies

Nuisance trippings of residual current circuit breakers or ground fault protectors of power sources connected to computer and electronic loads

Computer Based Harmonic Measurement Systems: Discussion And A Realization

Any industrial plant that has a considerable amount of rectification may experience harmonic-related problems (e.g., solid-state control circuit malfunctioning, communication noise, etc.). The application of power-factor correction capacitor banks to such a system will generally increase the likelihood of such problems occurring. To properly identify the cause of such problems and, in some cases, recommend solutions, an on-line analysis of the system may be necessary. This usually involves a harmonic analysis of the current or voltage waveforms observed in the electrical system. A description of an automated on-line harmonic measurement system used by the authors will be presented along with the advantages of using such a system. In addition, two specific examples showing the application of an automated on-line harmonic measurement system will also be presented.

James J. Toth

Papers

Benefits of an Automated On-Line Harmonic Measurement System