# Power Quality Impact and Its Assessment: A Review and a Survey of Lithuanian Industrial Companies
## 4 Results
The following color-coding is used: non-dangerous events are marked with black color, partially dangerous with orange, and dangerous with red. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Voltage, p.u. **} & \multicolumn{10}{c}{**Duration, s**} \\  & **0.01 \(\leq\) t \(\leq\) 0.2** & **0.2 \textless t \(\leq\) 0.5** & **0.5 \textless t \(\leq\) 1** & **1 \textless t \(\leq\) 5** & **5 \textless t \(\leq\) 60** \\ \hline
0.9 \textgreater{} U \(\geq\) 0.8 & 7 & 0 &  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Voltage, p.u. **} & \multicolumn{10}{c}{**Duration, s**} \\  & **0.01 \(\leq\) t \(\leq\) 0.2** & **0.2 \(<\) t \(\leq\) 0.5** & **0.5 \(<\) t \(\leq\) 1**  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Voltage, p.u. **} & \multicolumn{10}{c}{**Duration, s**} \\  & **0.01** \(\leq\) **t** \(\leq\) **0.2** & \multicolumn{2}{c}{**0.2 < t** \(\leq\) **0.5**} & \multicolumn{2}{c}{**0.5 < t** \(\leq\) **1**} & \multicolumn{2}{c}{**1 < t** \(\leq\) **5**} & \multicolumn{2}{c}{**5 < t** \(\leq\) **60**} \\ \hline
0.9 \(>\) U \(\geq\) **0.8** & 33 & 6 & 7 & 20 & 15 & 11 &  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Voltage, p.u. **} & \multicolumn{10}{c}{**Duration, s**} \\  & **0.01** \(\leq\) **t** \(\leq\) **0.2** & **0.2 \(<\) t** \(\leq\) **0.5** & **0.5 \(<\) t** \(  
The answers about electric machines are summed up in Tables 10-14: according to the opinion of the respondents, the closer the cell is to the upper left corner, i.e., to cell A1 (see Table 5), the less dangerous voltage sags. One company separately mentioned its electric generator. Additionally, the respondents provided the following information:  
1. Comments about MV three-phase electric motors: * \"The technological process is interrupted after each voltage sag, the production lines are halted, fabrics freeze in the cutting machines, cutting defects may occur.\" \"The company's electric motors and variable-frequency drives are very sensitive to voltage sags.\" * \"The company's electric motors are very sensitive to voltage sags. The company experiences losses after each dangerous voltage sag.\"  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Voltage, p.u. **} & \multicolumn{8}{c}{**Duration, s**} \\  & **0.01 \(\leq\) t \(\leq\) 0.2** & **0.2 \textless t \(\leq\) 0.5** & **0.5 \textless t \(\leq\) 1** & **1 \textless t \(\leq\) 5** & **5 \textless t \(\leq\) 60** \\  
* \"Voltage sags that are dangerous to 6 kV electric motors triggers the emergency automation, shifting from one power source to another for continuous energy delivery.\"
2. Comments about LV three-phase electric motors: * \"The company's electric motors are very sensitive to voltage sags.\" * \"The company's electric motors are very sensitive to voltage sags. After each dangerous voltage sag, the company suffers a loss of about EUR 920.\" * \"No effect was observed because the motors are shut down by the automation of the control panels.\" * \"Electric motors are sensitive to voltage sags. In case of a deeper voltage sag, the company's motors are shut down by overcurrent protection of frequency converters. It also happens that the motors without frequency converters are disconnected by the thermal protection. Supply interruption halts the production process, which restoration takes up to 1.5 h.\" * \"All company's three-phase electric motors are sensitive to voltage sags. After each voltage sag, the company suffers economic and time losses, and a lot of manufacturing wastes are generated. The most affected workshops are knitting, thread and net dyeing, drying, and impregnation.\" * \"Short-term voltage sags do not impact the work, motors up to 100 kW operate in self-starting mode.\" * \"The company's electric motors are very sensitive to voltage sags.