400hz system

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POWER_PIG

POWER_PIG

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Any of you ever install 400hz. systems?
Do you know of anything in the NEC that makes refrence to this matter?
 
PP

I installed a 400Hz converter about a year ago. I did not find much in the NEC. The job was supervised by an EE. I do remember that the raceways had to be non ferrous due to some induction principle of the 400Hz and the conductors were over sized.

Joe
 
In the '99 Code, 310-15 had a formula that indirectly uses freq. by taking into account skin effect and proximity effect in the term YC below.

I = [{TC-(TA+deltaTD)}/RDC(1+YC)RCA]^0.5

This formula is repeated in this version of the Code but direct references to freq. are pretty scarce.
 
Ok, Thx
I looked and looked, and came up with minimal information. Im wondering what the heck the advantage of theses systems would be?
 
They are beneficial for reducing the size of transformer needed for a given KVA, or motor for a given horsepower.

The transformer core mass for a given KVA scales as 1/frequency.

-Jon
 
winnie said:
They are beneficial for reducing the size of transformer needed for a given KVA, or motor for a given horsepower.

-Jon
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@ 135 % minimum due for this service are you sure ?
 
POWER_PIG said:
Ok, Thx
I looked and looked, and came up with minimal information. Im wondering what the heck the advantage of theses systems would be?
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If you require an induction style motor operating faster than 3600 rpm, you need higher frequency. I've seen the 400 hz running routers in industrial applications, WITH APPROPRIATE MOTORS. A 2 pole motor will spin about 24,000 rpm, a 4 pole about 12,000 rpm. This application is great here. The "more power in smaller frame" camp is telling part of the story ... thermal limits get you, but higher speed at the same torque is more power ... at 60HZ, a 10HP 3600, 5HP 1800, and 3HP 1200 might all be in a 215T frame.
 
I know that some of the land power run to airplanes is 400 hz
I've heard there is 400 hz equipment on board to reduce size and weight.


I won't swear to any of the second statement above.
 
Some mainframe-type computers (like Amdahl, NAS, or Fujitsu) run on either 400 or 415 Hz . The basic idea is to make the power supplies smaller and block disturbances from hitting the system. When last I saw some of these, they used Edpac MG sets in sound-insulating cabinets sitting in the computer room.
 
zbang said:
Some mainframe-type computers (like Amdahl, NAS, or Fujitsu) run on either 400 or 415 Hz . The basic idea is to make the power supplies smaller and block disturbances from hitting the system. When last I saw some of these, they used Edpac MG sets in sound-insulating cabinets sitting in the computer room.
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I believe that modern power supply technology, with the highly efficient DC-DC converters (operating FAR higher than 400 Hz), have replaced the rotating sets of old. Just as with motor speed control inverters, the 3 phase line is rectified then chopped as required.

This is stale memory time, but one advantage we were told (mid-60's) of rotating equipment was that it had high inertia flywheels to carry through "short" interruptions. I don't know how much capacitance would be required to accomplish that with modern switchers. UPS systems where that is critical use the battery for short to medium support. That technology should be applicable to energy storage of the 400-800V from a 208/240/480 3 phase rectifier output, but I don't know that it is.
 
russ said:
I know that some of the land power run to airplanes is 400 hz
I've heard there is 400 hz equipment on board to reduce size and weight.


I won't swear to any of the second statement above.
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This was the application that I installed the system for in an earlier post. The company works on aircraft electronics.


Joe
 
400hz is great stuff, and typically supplied as 3 phase. All you need to be concerned with it what connects directly to it. The items that feed off of the 400hz have to be 400hz components. There are some gains in being able to use smaller cables based on the higher frequency, a factor you typically don't consider when you universally use 50-60Hz.

It converts to DC or standard AC 50-60Hz very easy, and you don't have as much trouble with reactive power loads. I am also pretty sure that your True Power to Horsepower ratio is superior. Again, this is typically used in aircraft were a smaller part operating more efficiently translates to less weight.
 
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