Vibration and temperature are the most common parameters used for machinery protection. Of these, temperature has been used longer, probably because it was available first and was better understood than vibration analysis. However, it is now said that vibration gives an earlier warning and more information because the vibration signal contains many frequencies and many amplitudes, each pertinent to some moving part of the machine.
Vibration monitoring has become more cost effective and easier to implement. Simple 2 wire systems produce instantaneous readouts on control systems which in turn can generate alarms. The days of operations staff noting high vibration levels have gone and automation has assumed that role.
Sources of vibration
Unbalanced rotating equipment, misalignment of machines, bent shafts, oil whip in journal or sleeve bearings, gearboxes and vehicle movement – amongst others – all have the potential to generate destructive vibrations. Vehicles driven on rough terrain vibrate, and geological activity can cause massive vibrations in the form of earthquakes.
How is vibration measured?
A vibration sensor or a transducer is a device used to convert vibration into another energy type, such as voltage or electric current. It is normally used to measure machinery or structural vibrations. The most common vibration sensors include velocity, accelerometers and proximity probes.
Protection against catastrophic failure
This is a very important consideration and many monitoring applications are dedicated specifically for this use. Years ago there were two ways to operate a piece of equipment. One was to shut down the machine at regular intervals for inspection, even if it did not need repairs. The other was to let the machine run until catastrophic failure occurred.
Reduced down-time costs
If the exact nature of the problem is known, the machine can be disassembled at the proper places and the required parts can be on hand when repairs are required. The cost of equipment failure is tremendous; so is the lost production due to shutdown, particularly unscheduled shutdown. Vibration analysis can be useful in helping to determine the exact nature of the problem. So, the answer is to keep a check on the mechanical health of the machine and keep it operational as long as possible.
ProvibTech’s new cost effective vibration transmitters can extend the running time between shutdowns and are ideal for use in the harsh conditions found in the mining and quarrying industries.
| Tel: | +27 11 608 1551 |
| Email: | [email protected] |
| www: | www.randci.co.za |
| Articles: | More information and articles about R&C Instrumentation |
© Technews Publishing (Pty) Ltd | All Rights Reserved
printer friendly version