A condition monitoring system for monitoring a rolling element bearing. The system includes a signal processing unit and a vibration energy harvester. The vibration energy harvester provides an electromagnetic transducer. When vibrated, a coil moves relative to a static electromagnetic field to create power. To create a compact and efficient condition monitoring system, it uses the electromagnetic transducer also as a vibration sensor, a velocity sensor. The signal processing unit determines if the bearing has been damaged and in some embodiments also the extent of the damage. The electromagnetic transducer is attached directly or indirectly to the rolling element bearing.