Vibration monitoring on equipment such as cranes, hoists and screw jacks has traditionally been difficult.  These are often driven by an electric motor rotating at perhaps 1500 rpm, but the final hoist drum or travel wheel rotates far slower – perhaps only a few rpm- with intermediate shafts rotating at speeds somewhere between these values. 

Conventional vibration monitoring is difficult because you need to place sensors in line with each of the bearings on each of these different speed shafts, which is not only time consuming, it can be very difficult to access – especially to try and take readings when the crane is in operation.

A solution can be found through Torsional Vibration measurements – effectively using the drive motor as a torsion sensor, enabled by a Model-Based Voltage and Current system, such as the Faraday Predictive S200 system.  This is a small box that fits inside the motor starter cabinet, and measures voltage and current whenever the machine is in operation.  The S200 automatically identifies distortions to the current that have not come from distortions on the voltage supply, and therefore must have been caused by phenomena in the machine.  Because shafts transmit torque very efficiently from one end to the other, the motor can “see” signals throughout the machine, with different characteristic frequencies clearly identifying faults from the different speed components.

Recent applications in the nuclear power industry have detected faults on cranes, screwjacks and other complex equipment including rubbing brakes, misaligned drive shafts and rubbing screwjack nuts as well as faulty motor winding insulation.  Even the best vibration system would struggle to do all of that!

And the best news is that these are not “Nuclear priced” but are inexpensive units accessible to all industries.

For more information see
www.faradaypredictive.com