SUPERV I S ION AND CONNECT I V I T Y
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— Energy Measurements Network Analyzer
Effective preventive and corrective action can be implemented through accurate analysis of faults, thereby improving the efficiency of the system. Applications Electrical equipment is designed for optimum op- eration under constant and uniform voltage level, as close as possible to the rated value. In addition, industrial equipment, working on a three phase supply, requires the three phase voltage levels to be balanced. Power quality is a description of how well a power system complies with the above ideal con- ditions. Power quality issues can have negative con- sequences on the components and on the energy efficiency of the network. Thus, power quality moni- toring is becoming more important in modern power systems, and will be a key part of the smart grid of the future. In particular, power quality evaluation includes the following aspects: • Deviations of voltage average value from the rated value • Short decreases (sags) or increases (swells) of voltage value • Voltage imbalance, i.e., difference in voltage val- ues between different phases • The presence of current and voltage harmonics. — The Network Analyzer function available in all Ekip Touch trip units, enables monitoring of the quality of energy based on harmonics, micro-interruptions or voltage dips without the need for dedicated instrumentation.
Distortions of the voltage value (sags, swells) and/ or frequency can have harmful consequences, espe- cially for process industries, leading to possible production stoppages with consequently expensive downtime, damage to motor drives and damage to PLCs. Examples of process industries that can be badly hit by voltage instabilities include the plas- tics, petrochemicals, textiles, paper, semiconduc- tor, and glass industries. Voltage sag occurs when the value of the voltage is reduced below the rated one for a certain amount of time. Similarly, voltage swell occurs when the voltage is increased above the rated value for a cer- tain amount of time. RMS voltage values and frequency are two funda- mental features of a voltage signal, but the “pure- ness” of the voltage waveform is also an important point. An ideal voltage waveform should be a per- fect sinusoid, but this is not something that is nor- mally seen in the real world. Frequencies other than the fundamental are always present. These frequencies are called harmonics: a harmonic of a signal is a component frequency of the wave spectrum that is a multiple of the fundamental fre- quency. Harmonic content is an issue that is be- coming increasingly debated: technological devel- opments in the industrial and household field have led to the development of electronic equipment which, due to their operating principles, absorb a non-sinusoidal current (non-linear load). Such cur- rent causes a non-sinusoidal voltage drop on the supply side of the network with the consequence that the linear loads are also supplied with a dis- torted voltage.
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