# Power Quality Impact and Its Assessment: A Review and a Survey of Lithuanian Industrial Companies
## 4 Results
If at least one device is disconnected, the entire production process stops, and the production line must be cleaned before the restart. Losses depend on voltage sag magnitude, duration, location (feeder), etc., and are calculated separately in each case, but when the work efficiency is 100%, hourly losses are about EUR 22,700.\"
* \"We did not fill the tables for a simple reason--the voltage sags are practically undetectable without special monitoring equipment, thus only longer supply interruptions can be taken into account. The company's losses are increasing rapidly with each passing minute. Voltage sags are particularly common in windy or adverse weather conditions. Under such conditions, the weaving looms usually cannot work.\"
* \"The technological process is interrupted after each voltage sag. The production lines are halted. The plastic shedders, screw loaders and centrifuges become logged with polyethylene pieces. After each voltage sag, the plastic solidifies and must be removed from granule agglomeration units. The restart requires human resources and takes up to 4 h. Particularly sensitive equipment is the plastic film making machines. After the shutdown of the lines, a large amount of plastic waste is generated (about 4000 kg per stop). It takes up to 2-6 h to restart all the lines. It has been estimated that the company suffers a loss of EUR 5000-8000 after each dangerous voltage sag.\"
* \"The terminal experiences economic losses and non-material damage after voltage sag or supply interruption. After each event, the technological process is interrupted, both the operation of equipment and transport traffic are halted, and the loading process becomes unsafe and longer. The recovery takes up to several hours due to the human factor: as the person responsible for the company's electrical sector, after a receiving a notification about the problem, I have to go to the terminal (within 4 h) and deal with the consequences outside working hours. Metal-halide lamps, which illuminate the territory, cool down and again turn on only after 30 min. Particularly sensitive equipment are computers and controllers. Some of them have UPSes. In our opinion, PQ monitoring system is not worthwhile and not cost-effective, because it only records voltage sags but does not prevent them. The monitoring, including the sharing of relevant information, must be carried out by the DSO. Most often the faults occur in the 10 kV grid, and the duration of supply interruption is equal to the automatic transfer switch time delay.\"
* \"The company does not have PQ analyzers or other devices; thus, we cannot provide the data about both magnitude and duration of voltage sags. Our company does not experience any significant losses due to voltage sags--the technological line is forced to stop several times a year. The restart takes up to 1 h. We do not plan to install the PQ mitigation devices as it would not be economically viable. In our opinion, more problems are caused by voltage transients. The devices are often disconnected during thunderstorms by control panels. The installed surge arresters are not efficient. In order to avoid such a problem, we stop the work by ourselves when the thunderstorm is approaching.\"
* \"PQ is particularly important for the production of plastic products of our company. The company has vulnerable equipment, and experiences heavy losses if the technological process is disrupted by a short circuit. There have been cases when the equipment was damaged and needed to be replaced. It usually takes two weeks from ordering new equipment parts to their replacement. Meanwhile, damaged unit is not available for use, and our company suffers heavy losses.\"
* \"After each voltage sag, the company suffers a loss of EUR 5000.\" The filled form is valid when at least one logically completed table is provided. In total, responses from 52 companies were taken into account. The total number of responses is given in Tables 10-29.