# Bearing Failure

829 Words4 Pages
increase as the load and fault severity increase and the features of the fault can be best recognized under higher loads (Alwodai 2012). Figure 33 Current power spectra under different load conditions (Alwodai 2012) Bearing Failure The approximated inner and outer raceway characteristic bearing fault frequencies are determined by formulas (Benbouzid & Kliman 2003; Blodt et al 2008; Nandi et al 2005): Wheref_BRG is the characteristic fault frequency for bearing failure, f_s is the supply frequency for motor, m is any integer, f_ir and f_or are characteristic frequencies for inner and outer ring respectively. Extensive knowledge of bearing design is required for an exact calculation. However, in practice, these frequencies are commonly…show more content…
Besides the vibration signal, another two parameters measured include: Temperature Temperature is an important parameter in motor operation. Bearing and winding are the two components most affected by excessive heat. Trending temperature measurements is an easy and fast approach for motor overheating estimation. Common reasons of overheating are overloading, bearing faults, misalignment, unbalance, ventilation, high ambient temperatures and power supply variations. Bearing temperature is a direct indicator for bearing faults. Many researches indicate that for any types of bearing failures, normally friction increases which results in rise in temperature of the bearings. Therefore, bearing temperature can provide useful information reflecting bearing condition and motor health (Schoen 1995). Load torque Both bearing fault and fan unbalance will cause load torque variations. For example, if there is a hole in the inner raceway of a bearing: each time a ball passes that hole, an extra mechanical resistance will be generated when the ball tries to move over the hole. As a result, the load torque experiences a small increase at each contact between the defect and another bearing element. By observing the torque spectrum, we can see that the bearing fault-related torque variations occur at the characteristic vibration frequencies illustrated in chapter 6 (vibration monitoring) because they are both of the same origin: a contact between the roller the