SHAFT GROUNDING RINGS — PROTECTING VFD DRIVEN MOTORS FROM BEARING CURRENTS

The present official supplementary reference document was specifically prepared and officially released by the  specialists of the world respected Electro Static Technology ITW and is primarily dedicated to the VFD, standing for the variable frequency drives. When the PWM VFD, i.e. pulse width modulation drives were developed using IGBTs, i.e. the insulated gate bipolar transistors, this advanced and newly presented technology was first applied to controlling electric induction motors in both commercial and industrial applications.

The advantages were obvious: Torque and motor speed could now be precisely controlled to optimize both process and energy requirements, The potential to save energy by operating motors at only the required speed and, at the same time, maintaining applicable torque requirements would potentially result in a 20% to 50% energy savings, Processes can be optimized and controlled by computer processing systems to achieve productivity increases or energy savings.

Nowadays, the use of these variable frequency drives is slowly getting increasingly common when making attempts to save the energy in HVAC systems and to reduce the associated energy costs. When using the VFD technology, please note as necessary that this type of motors shall always have the bearing protection in order to ensure reliability and safe operation.