# Power Quality Impact and Its Assessment: A Review and a Survey of Lithuanian Industrial Companies
## 4 Results
After each dangerous voltage sag, the company can suffer a loss of up to EUR 28,000.\"
* \"The controllers shut down when the voltage drops below 70% with all the consequences that follow (interruption of the production process, etc. ).\"
* \"Some controllers are very sensitive to voltage sags. The controllers must be restarted, which takes about 10 min. The company can suffer a loss of about EUR 500.\"
* \"The work of heating and ventilation equipment, elevators, access control systems, and traffic management systems is interrupted. The exact duration [of voltage sag] is unknown.\"
* \"We have \(11\) programmable controllers that control the temperature of our diffusion furnaces. These controllers are very sensitive to voltage sags. Depending on the situation, losses can reach up to EUR 16,000.\"
* \"Shorter voltage variations are dangerous, but when supply interruption is longer than 1 s, the controller restarts correctly\" (see Table 17). The answers about lighting are summed up in Table 18. It is divided into internal and territory. Inadequate lighting poses a danger to occupational safety and health. Trafficlights and railway signals can be distinguished as a separate case of the lighting (Table 19). The following comments were received:  
* \"We did not notice the effect [of voltage sags on lighting].\"
* \"We do not know exactly whether voltage sags have an effect on lighting.\"
* \"In case of a larger and longer voltage sag, indoor lighting turns off, but quickly recovers. Voltage sags have a greater effect on metal-halide lamps--the cool down period is required before switching on. To conclude, voltage sags have not a significant impact on lighting.\"
* \"In our company, the main source of lighting is various types of fluorescent lamps. In some cases, voltage stabilizers are used.\"
* \"The lighting usually recovers, but LED pulse power supplies often fail. This directly affect the manufacturing process and contributes to unexpected expenses.\"
* \"During loading, the switching off of the lighting of both the loading ramps and the territory (20 ha) poses a risk to occupational safety and health as well as increases loading time.\"
* \"LED power supplies are very sensitive to voltage sags. In our company, the share of LED lamps is 85%.\"
* \"The lighting remains working until the voltage drop is up to 50% of nominal value. If the voltage drop level is higher and the lighting is turned off, accidents are possible near the equipment in operation.\"
* \"Most lamps have power inverters. When the voltage drops below 50%, they turn off. This is dangerous for occupational safety and health--injuries are possible.\"
* \"[Voltage sags] may change railway signals: if the signal changes from allowing to stopping, train emergency braking and delay is possible.\"  
The answers about servers, stationary computers and telecommunications equipment are summed up in Tables 20-22. Servers are sensitive to voltage sags, but some companies answered that this can be resolved with UPSes. In the case of unexpected computer shutdown, unsaved data may be lost. In addition, some companies mentioned their communication network, for example, Profinet, an industry technical standard for data communication over Industrial Ethernet. Accordingly, it can be concluded that poor PQ is a serious obstacle to the industrial internet of things. The respondents provided the following information:  
1. Comments about servers: * \"We have five servers. The installed UPS can maintain the voltage up to 8 min; therefore, a longer voltage sag is not tolerated. Each time the system reset costs up to EUR 300.\"
* \"Micro and short-term power outages are dangerous [to servers] due to UPS switching delay.\"
* \"Voltage sags are very dangerous to servers and can damage their electronic components.\"
* \"Voltage variations disrupt our servers. They begin to conflict with each other, and their contacts may burn. Servers are very sensitive to voltage sags. The entire company's activities are suspended while the faults are being fixed.