Measuring power and energy in electric circuits

Measuring power and energy in electric circuits

Power meters and network parameter analyzers are intended for identifying anomalies of power supply in single-phase or triple-phase networks. They enable power and energy analysis, and also quality control of electrical power. They can also be used for continuously recording measured values and identifying various occurring events. These tools are useful for applications in all industrial and individual sectors with different levels of preciseness and standards (e.g. in compliance with norms like IEC 61000, IEC 61010, EN 50160). The market of these devices is very broad.

Simple measurements

In the simplest versions of network analyzers are used in single-phase or triple-phase, triple-phase circuits or four-circuit with a possibility of data transmission through a communication interface (e.g. ModBUS, Ethernet) of all main characteristic values for electricity networks, including counting out active and passive energy (just like an electric energy meter). In some cases they have programmable alarms or impulse outputs for retransmission of parameters. Often the measurement of basic values (currents and voltages) is conducted with a sampling method, which allows for proper measurement of the true effective value (TRMS) even during deformed processes - being more and more common in modern electric installations.

Electrical disruptions monitoring 

Two types of network disruptions should be monitored: permanent and occasional. The first ones can be observed through clamp multimeters with measurements of true effective value and oscilloscopes with differential inputs. In the case of occasional disruptions it is recommended to use network parameters analyzers. To detect recurring disruptions, it is common to measure true effective value with a multi function device or clamp multimeter and displaying the process of three phases by the usage of an oscilloscope with a differential input.

Electrical energy quality testing and problem-solving

On the market, two basic categories of energy quality analyzers are available: for verification of delivered voltage (with detection of harmonic and flicker light) and for solving problems. The first one is an effective statistical tool, but do not solve problems due to occasional disruptions. The second one provides long-term monitoring with automatic recording of current and voltage processes disrupted periods. The purpose of monitoring is to capture events which caused problems. Another, also important issue, is localization of network disruption analyzers. A good practice is to monitor the power supply system as the most sensitive equipment.

Analyzers are intended for solving problems, additionally to the continuous monitoring, generally providing additional functions such as network insulation from grounding (helpful with further increasing of the safety and cost level) and automatically identifying insulation errors (can occur during work). Increases the flexibility of the production workplace and minimizes outages.

Harmonic analysis

The usage of analyzers in installations is also useful for detection of effects of harmonic and undetermined states. Rapid change in the powering voltage process caused by a breakdown leads to values within limits of several thousand volts. Switching climaxes of power converters also cause intermittent effects. Low voltages, with which modern microelectronic devices work, make them more susceptible to disruptions in the power network. Apart from the effect on these electronic devices, these states can also cause disruptions in data or control systems. Another problem, considering a significant number of industrial and consumer devices working with rectifying systems, is the implementation of harmonic into public networks (distribution).

Vectorial analysis

Finally, we have to take into consideration precise devices verifying electric parameters and vector analysis of circuits (VNA). They are based on one of the main measuring methods applied in the sector of radio and microwave frequencies. These systems allow for analysis of active and passive components, such as filters, amplifiers, mixers and multiport modules. 

Vector network analyzers are optimized in terms of high speed of measurement, using  frequency scanning, thanks to which the results are acquired faster than while using  a single source signal connected to the receiver, such as the spectrum analyzer. Thanks to the operation of calibration, vector network analyzers provide the highest level of preciseness while measuring elements of radio frequencies.

Author: Maciej Dumania – DACPOL

contact: +48 22 70 35 223

lem_i@dacpol.eu

m.dumania@dacpol.eu