Wind Turbine Mechanic

Hello everyone. This is my first post on here. I am 39 years old and I received my St Jude pacemaker on December 18 of 2012, only a few weeks ago. I have had two open heart surgeries in my life, the latest one was 4 years ago to replace the mitral valve. My cardiologist said that the scar tissue from my previous surgeries is what started to interupt the electrical signals in my heart. I had an average heart rate of 43 two days before my surgery. It would drop below 30 several times at night along with an irregular heart beat sometimes.
Anyway, I am a wind turbine mechanic and have been for the last five years. I talked to my cardiologist about my job and he said the electrical interfence shouldn't be a problem as long as the turbine was off when I was in it. The St Jude rep that adjusted my PM after it was put in wasn't so positive though. They were concerned about the transformers right at the base of the turbine (120 kV to 690 V) and the electrical fields of all of the 690 volt motors and heaters that are everywhere on these turbines. Our turbines also have large AC-DC-AC frequency converters right inside the base of the turbine also that could pose a problem. These frequency converters are operating when the turbine is online and to shut the turbine down, you have to go to the control panel right next to these converters inside the turbine. Almost everything in these turbines(including the converters) are in metal cabinets that are grounded very well though, so I'm not sure if it would be an issue or not.
Just wanted to see if anyone on here has had any experience with larger industrial motors and how strong a magnetic field they generate.

Tracy

4 Comments

Generators

by fishfighter - 2013-01-06 01:01:12

Myself, I used to run a 600MW station. On my job site in the last two years, two of us were in need of a CRT-D. Well, at that point, the company would not let us back on the unit even though I worked inside the controlroom which was 30' away from the generator.

Good luck,
Paul

re:

by tdm5032c - 2013-01-06 02:01:31

Thanks for the comment, Frank. I really appreciate your input. I guess too that my employer will have to do some measurements. They should have the test equipment as we also operate a nuclear power plant. I don't work on that side though.(the dark side;)

What you said about the current is true. These things produce quite a bit though. Our big ones are 2.3 MW which works out to be a little over 1000 amps per phase. Our smaller turbines are 1.3 MW, which is 500-700 amps per phase. Just not sure about the magnetic fields on ac versus dc voltage. The converters convert the ac coming in to dc in order to control and adjust the frequency and then converts it back to AC. Pretty advanced machines actually.

Tracy

Depends

by ElectricFrank - 2013-01-06 02:01:57

It's not the voltage, but rather the current that creates problem magnetic fields. Most modern electrical power equipment (which turbines are) is well shielded both magnetically and electrically as part of efficiency standards. (any energy leaking out is energy lost). Another possible risk is that of having an electrical failure (lightning caused, short circuit, out of sync, overload) happening while you are close to the panel. During these events you can have large phase unbalances which create unpredictable fields.

My guess is that your employer would have the last word on this.You must have some rigid safety standards for working around such equipment. They may even have measured field information.

I'm an electronic engineer and have only limited experience with power equipment. My most exciting experience is bringing two 100KW field generators into sync for parallel operation. Even at that level it's impressive if you miss.

frank

re:re

by ElectricFrank - 2013-01-07 12:01:11

That's big time stuff. The AC coming down from the turbines must be on relatively close spaced conductors since they are inside the tower. That does a nice job of canceling magnetic energy. Same with the DC since it is handled inside the converters. I imagine the grid side is also close spaced conductors with a transformer farm stepping it up to transmission line level.

That must be interesting handling a constantly changing source at that power level. I once had a chance to watch the meters on a hydro dam during a desert lightning storm. To see a generator that size have its load dumped and then pick it up in sync was quite a thrill.

Good luck on returning to the job.

frank

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