There’s a saying about chess that a person can play the perfect game by making all the right moves, but can still lose. This axiom holds true for rotating equipment; eventually, all rotating equipment, such as electric motors, generators, gearbox, etc, fail. What isn’t so definite is when they’ll fail.
Writing at the EngineerLive website, Richard Emery shares information on equipment failure and provides some suggestions to extend the life of that equipment.
When addressing the operating costs of a modern heavy industrial production facility, most industrial processes will involve electric motors and all will need the services of a generator, either directly on site or indirectly through the electricity supplier. Prolonging the service life of these vital pieces of equipment can deliver significant improvements in their life cycle cost as well as operational savings for the production facility.
Life cycle cost (LCC) is a vital driver in modern engineering and comes to the fore when the initial purchase cost of large rotating machinery has been amortised. Running costs and avoiding unscheduled downtime are then at the top of an operations team’s agenda. Sulzer, as a global repairer and 24hr service provider with its own worldwide network of service centers for both motors and generators of any size as well as turbomachinery and pumps is in an ideal position to provide some guidance on improving LCC.
The designs of multi-megawatt motors and generators have many similarities; they are classed as large rotating machines that have a stator and a rotor both of which contain windings that need to be insulated and bearings that need to be lubricated. Obviously the major difference is one generates the electricity while the other consumes it. However, by looking at the similarities it is possible to employ similar methods to prolong the service life of both.
We’ve written about the signs your electric motor is about to die:
- Electric Motor Running Hot
- Sludge in the Reservoir
- Excessive Energy Usage
- Hot Gearbox
And we’ve graphically demonstrated why electric motors fail, so I think we have that area covered. But, Emery offers three suggestions to consider following to extend the life of your motors and generators: begin a condition monitoring program, pay attention to winding insulation degradation, and improve the reliability and efficiency of your equipment.
On larger machines, the use of vibration monitoring equipment and thermal imaging cameras can provide vital information and indicate the early signs of a bearing beginning to fail. Both of these predictive maintenance methods can be used without having to stop the equipment and they can provide regular data for a preventative maintenance program.
Winding insulation degradation
The electrical insulation applied to motor and generator windings degrades over time and according to the operating stresses it is subjected to. Voltage imbalance, over and under-voltage, voltage disturbance and temperature all play a role in the degradation of the insulation. Using a technique such as partial discharge analysis can provide vital information about the condition of the stator.
Improved reliability and efficiency
Improved production techniques and insulation technologies allow modern coils to improve the efficiency and longevity of existing equipment. Throughout the manufacturing process, however, quality control is essential to maintain the production of highly reliable, uniform coils. Sulzer’s Birmingham Service Centre for example uses CAD design, modern insulation technologies and testing, combined with its own copper rolling mill to provide high quality coils that can be produced and installed in a very competitive time frame.
In the end, Emery advises that using a combination of predictive maintenance programs, such as vibration analysis, IR scans, and discharge testing gives your motors and generators a chance to work longer and more efficiently.