“…The signals taken into account when monitoring the condition of motors are among the most diverse. The valuable motor output signals provided by the motor and suitable for condition monitoring are acquired by means of appropriate sensors placed on the motor or on its rotor (most frequently vibration sensors [1][2][3][4][5][6][7][8][9][10][11][12], temperature sensors [2][3][4][5][6]10,[13][14][15][16][17][18], instantaneous rotation speed sensors [6,9,14,16,[18][19][20][21] acoustic sensors [5,8,11,12,14], and rarely magnetic field and flux sensors [20,22,23] or stray-flux sensors [6,24]).…”