Replacing MG set

[vangjer]

Hi all,

So we have an old, old equipment from the 40's that is using an MG (motor-generator) set. We are thinking about replacing this MG set with a solid-state power supply or another MG set with today's motor technology. What do you guys think?

Inputs:
-30kW, 3 phase 440V, 60Hz

Output:
-90-240V, 1 phase, 180Hz
-124VDC

 

[rasevskii]

What is the 180Hz used for? Is it a continuous demand or occasional use during a manufacturing process? Often used for overvoltage testing of transformers at the factory, also for concrete vibrators...

The DC supply can be gotten from a small rectifier in any case, or is that the exciter for the 180Hz generator?

rasevskii

 

[vangjer]

Your right on track, the 180Hz is used to excite our x-ray tubes. The DC is mainly for the exciter to control the voltage for the generator (90-240V)

 

[rasevskii]

Well, go ahead and search on the web for 180Hz, or 180Hz generator, or 180Hz supply and see what comes up. I can't think of any supplier offhand for such equipment. I was once involved with a large 180Hz machine of 3 MVA from ASEA, but I doubt any of the major suppliers offer such small units.

rasevskii

 

[ScottyUK]

Pacific Power make some nice frequency converters, although I'm not sure what kind of load an X-ray machine imposes on the source. Rotating plant is generally a lot more tolerant of awkward loads than electronics.

http://www.pacificpower.com/English/Home.aspx

Companies who make 400Hz ground equipment for the aviation industry might be able to make you a 'special' although the following equation tends to be fairly accurate: aviation supplier + custom build = very expensive.


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If we learn from our mistakes I'm getting a great education!

 

[DickDV]

The old MG set motors will likely not be suitable for rectified unfiltered DC power without significant derating. The magnetics were designed for smooth generator DC and will overheat on DC with ripple on top.