Detection and evaluation of electrical power quality
High quality of voltage ensures operational safety. Modern production processes in particular, with their power-electronic drives and controls, depend on a high quality of the voltage supply. These enable considerable energy savings, optimize processes and increase productivity. Unfortunately they also degrade the voltage quality due to their load characteristics. This requires both precise planning in advance and qualified troubleshooting in the event of problems.
Electricity as a resource
A ressource that is usually not given sufficient attention is the electrical energy supply. Yet it is crucial for a stable and trouble-free machine operation. The primary effect of electrical energy is generally not visible and if it is, it is always not desired. Experienced electricians readily confirm, "If you can see, hear, and/or smell electricity, it usually becomes expensive."
Until these effects occur, the quality of the electrical power supply in most companies, perhaps aside from energy consumption, goes unnoticed. In retrospect, however, this sometimes turns out to be a momentous mistake.
In order to classify deviations from the original form, the sine, a mathematical procedure, the so-called Fourier transformation according to Jean Baptiste Joseph Fourier (1768 to 1830), is used. The result of this method are the so-called harmonics. The use of this complicated calculation is finding out how combinations of different equipment with differently distorted currents react. In addition, a statement can also be made about the effect of the distorted current on the voltage. This is where things get interesting. This is because all the operating equipment in the network feels this impairment; disturbances in the current only affect the generating equipment itself and the transmission media like cables, transformers and protective devices. The disturbances on the voltage not only affect the layers in which they are generated, but are also transmitted to layers above and below. For this reason, different limits and compatibility levels have been defined for the standardization of different networks.
If the limits are exceeded at a certain point in the network, the cause needs to be found. If there are several subscribers at the connection point, every single one of them needs to be checked. The level of the permissible disturbance in current consumption depends on the ratio of connected load to short circuit power at the feeding point. Ideally, an evaluation and dimensioning of possibly required compensation measures should be carried out and taken into account during planning of the facility. This is both needed to ensure the operational safety of the own facility and for the safety of other network operators.
In order to prevent delays and subsequently incalculable additional costs, experts with sufficient specialist knowledge are required when planning new plants and plant extensions. KBR colleagues from the PQ department are trained "Power Quality Experts (VDE)".
Summary - Recording and evaluating the electrical power quality is worthwhile
In any case, an evaluation and recording of the electrical network quality pays off in terms of operational safety. Even if the energy supplier does not threaten with disconnection, initially unexplainable disturbances or even damage to equipment can be explained and set in connection with certain network parameters. As soon as the cause has been detected, a solution for the problem can be found as well. If the result is a clean network, the often used statement by machine manufacturers: "There are harmonics in your network, the error has nothing to do with our machine", can easily be nullified.