How applicable are motor diagnostics techniques to diagnostics on permanent magnet generators? Mechanically they are strikingly similar, but the electrical configuration is different enough that the techniques wouldn't be 100% transferrable.

I'm building a test rig to investigate generator failures, but would like to see if my results extend into the motor-diagnostics realm.

Thanks,
Jeff

Jeff

These might be of interest

Electrical Motor Diagnostics for Generators


Electrical Motor Diagnostics for Generators Part 2

I would also appreciate hearing some experiences from other forum members.

Terry O

That's great information; and actually it appears that MCSA and other motor-specific diagnostics techniques transfer rather well to generators. That's good to know b/c there's such a good knowledge base out there for motors and associated diagnostics.

Generators, I would assume, comprise a much smaller portion of the 'rotating electric machinery' categoryt, though. Just an observation. Any other comments are welcome; thanks for the info, Terrance.

Jeff

MJroc,

Have been using ESA and MCA on generators with the Coast Guard and wind turbines for a while. The actual secret is not to use Current Signature Analysis, but actually it is Voltage Signature Analysis. Current evaluates the load, voltage evaluates the supply side. The ultimate supply is the generator.

Sincerely,
Howard

Thanks, Doc--you'll have your hands full with wind turbine applications considering their growth; nice work. Considering bearings (or at least mechanical issues) account for about half of motor/generator problems, have you had success identifying these types of problems using those techniques?

Jeff

Here is another example of the use of motor condition monitoring on generators. There is an example beginning on page 9 of the application of MCM to a generator.
Steve Shores

Motor_Condition_Monitoring_Article.pdf (647 Kb, 54 downloads) motor monitoring paper

I have been doing current spectrum analysis on induction generators on hydro-turbines for many years. Actual operating speed is above synchronous speed (for example 906 rpm). I have found electrical as well as mechanical faults.

Walt

I thought most of those wind- and hyrdo- turbine OEMs had their own analysis packages?

I have seen OEM monitor packages offered for wind turbines. There are plenty of hydro machines with little or no monitoring systems installed. Just because an OEM has an "add-on" does not mean that it offers good value.

Walt

Good point, Walt. It's interesting, though; you'd think the OEMs would have the best idea of how their things fail because they designed them. Although maybe the objectivity of a third-person has some good value. The hard part is convincing the OEM that you know better than them on something they made.. Sort of like someone else disciplining your own child!

MJroc:

I have been away for a while. To answer your question from before.

Not only have we been able to identify electrical issues using the Voltage Signature analysis side of ESA, but we have also been able to identify mechanical issues in the generator and the driver. For instance, in the Coast Guard generators that I was evaluating as part of our study (and troubleshooting) we were able to identify problems in the diesel engines driving the generators.

You don't want to necessarily replace other technologies with just ESA, but you might want to enhance them with it.

Sincerely,
Howard