## 2 Experimental Test Rig and Data Description  
The data set used in this work for is collected from the bearing datacenter administrated by faculty of mechanical engineering, Paderborn University, Germany. The overall data were acquired from 32 experimental bearings and were classified into healthy, artificially damaged bearings, and real damaged bearings with an accelerated lifetime test. The testbed is shown in Figure 1 and consists of a permanent magnet synchronous motor, operated by a frequency inverter with a switching frequency of 16 kHz. Along with motor currents and vibration, other supportive measurements named as speed, torque, temperature, and radial load are also available [50].  
The test rig was driven under several working conditions to diversify the dataset. The working conditions are listed in Table 1. The damage size, location, geometry, and occurrence in the test rig followed the ISO 15243(2010) standard.  
In our study, among the 32 bearings, we considered the motor phase currents of two phases (CS1 and CS2) from 17 bearings which include healthy bearing and those with inner and outer race faults as mentioned briefly in Table 2. The current signal is recorded with a current transducer (LEM CKSR  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**No.**} & **Rotational Speed** & **Radial Force** & **Load Torque** \\ \cline{2-4}  & **(S)** & **(F)** & **(M)** \\ \cline{2-4}  & **[rpm]** & **[N]** & **[Nm]** \\ \hline \(1\) & 1500 & 1000 & 0.7 \\ \(2\) & 1500 & 1000 & 0.1 \\ \(3\) & 900 & 1000 & 0.7 \\ \(4\) & 1500 & 400 & 0.7 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Operating Conditions.  
Figure 1: Organization of the test rig.  
15-NP). For each setting, there are 20 files containing 4 s of data, saved in mat file format. In our analysis, we considered the current signal of 1 s rather than the whole 4-s duration for both phases. The sampling frequency was set at 64 kHz; therefore, the initial dataset is a matrix of size 2720 x 64,000.  
Time domain representation of current signals recorded from three bearings (healthy bearing, bearing with inner ring fault, and bearing with outer ring) are provided in Figure 2. The time domain signal depicts very subtle changes among the three signals. The frequency spectrum is presented in Figure 3, which reveals that each signal contains a 60 Hz component. This is the line/characteristic frequency. We evaluated the classifier performance with and without this 60 Hz component, which will be discussed in a later section.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{1}{c}{**Type of Bearing**} & \multicolumn{1}{c}{**Bearing Code**} & \multicolumn{1}{c}{**Damage (Main Mode \&**} \\  & & **Symptoms)** & **Label** \\ \hline \multirow{6}{*}{Healthy} & K001 & - & \\  & K002 & - & \\  & Bearing & K003 & - & \\  & Data & K004 & - & \\  & K005 & - & \\  & K006 & - & \\ \hline \multirow{6}{*}{Naturally Damaged} & KA04 & Fatigue: pitting & \\  & & KA15 & Plastic deformity: Indentations & \\  & Outer Ring & KA16 & Fatigue: pitting & \\  & & KA22 & Fatigue: pitting & \\  & & KA30 & Plastic deformity: Indentations & \\ \cline{2-4}  & & & KA04 & Fatigue: pitting & \\ \cline{2-4}  & & KI14 & Fatigue: pitting & \\ \cline{2-4}  & Inner Ring & KI16 & Fatigue: pitting & \\ \cline{2-4}  & & KI17 & Fatigue: pitting & \\ \cline{2-4}  & & KI18 & Fatigue: pitting & \\ \cline{2-4}  & & KI21 & Fatigue: pitting & \\ \hline \hline \end{tabular}
\end{table}
Table 2: Bearings considered in this work and their condition.  
Figure 2: Time domain signal of different bearing conditions.