# Power Quality Impact and Its Assessment: A Review and a Survey of Lithuanian Industrial Companies
## 4 Results  
In general, the companies agree that voltage sags are not desirable and may cause consequences, and sometimes miss more transparent information from the grid operator about the PQ events. The effects depend on such characteristics of the industrial process as length, speed, continuity, etc., but usually the process is interrupted and needs to be restarted, and as a result, companies experience economic losses. The following comments were received:  
* \"The technological process is halted after each voltage sag, five technological lines are interrupted, the crushers and the conveyors become overloaded with crushed stone. The restart takes up to 2-3 h. Particularly sensitive equipment are 0.4 kV induction motors installed in the automated lines. We do not know exactly whether voltage sags are dangerous to 0.23 kV electric motors and mechanisms driven by them.\"
* \"The technological process is interrupted after each voltage sag, the work of both the production line equipment and eight packing lines is halted. In the production facilities, the mass prepared for pet food production becomes rigid, and needs to be re-moved and disposed. The restart takes up to 1 h. After each voltage sag, we suffer a loss of EUR 8000.\"* \"Voltage variations damage technological processes and equipment, as a result of which the technological processes of water supply and domestic waste water treatment are interrupted. We do not know exactly how dangerous voltage sags are to both 0.4 kV and 0.23 kV electric motors and mechanisms driven by them.\"
* \"Voltage sags cause an emergency stop and sometimes a failure. The most sensitive equipment: refrigeration, product formation equipment, warehouse equipment, servers. After an emergency stop, it may take up to 2 h to start up the above-mentioned equipment, if it was not damaged during the PQ event. During this time, the temperature regime of the manufacturing premises becomes inappropriate, the products are not manufactured, and the employees experience downtimes. In the near future, we are going to install PQ analyzers, and therefore will be able to more accurately relate equipment stops and failures to the parameters of power supply.\"
* \"Our company has sophisticated automated technical equipment. Voltage sags and supply interruptions can have irreversible consequences for both the equipment and the production. Supply interruption during glass tempering can irreversibly damage the rollers of the glass tempering furnace. Glasses may stick to the ceramic rollers. The company experiences losses (both direct and indirect).\"
* \"The technological process is halted after each voltage sag, four production lines are interrupted. For the company, the most dangerous are micro-interruptions (sometimes they are multiple), which disturb the operation of our controllers. If at least one controller stops or loses the program, the controlling computer stops the production lines in an emergency manner. Then the line cannot be restarted because the products remain in it, and the products cannot be removed because the line cannot be started. This causes very long-lasting outages. There are cases of deletion of the internal parameters of the frequency converters as well as irreparable damage.\"
* \"In our company, the production process takes place non-stop around the clock. Voltage sags interrupt the process, and as a result up to 1-1.5 h can be lost. The technological process must be restarted. Part of the manufactured production must be disposed due to substandard processing. Electric motors, controllers, personal computers are sensitive to voltage sags.\"
* \"We do not have the equipment for voltage sag magnitude recording, we can admit that we are experiencing more and more disconnections. The company has many CNC machines for steel sheet, wire and pipe processing, and all of them are vulnerable.