ECN Forum Forums Photo Discussion Forums Photos for General Discussion Aloha Vacation

Come on kids...read the thread....There's a reason this was on the Arizona...One mistake, which I chose to leave in my post, and you guys are ruthless.

E57....there's a mess of lighting on the ship that is run as you noted. Same stuff that you see around every construction site. Little yellow baskets protecting a zillion watt bulb.

Anyone know if this big stuff is 400Hz. I noticed a bunch of power related buildings near the shore power box. I was wondering if they were doing some fancy stuff to convert it. I'm quite unfamilar with the miltary and how they use and abuse power systems.....

RSlater,
RSmike

RSmike:

My guess on the 60 to 400Hz conversion would be with the use of motor-generator sets or rotary converters (Basically a huge motor shell with the motor and generator windings on the same stator, IIRC).

We had only one rotary converter on our entire base and it was rarely used. I was told that besides the incredibly annoying whine it made (As compared to the "Dash-60" jet turbine generators?!?) it was also incredibly inefficient.

Why convert to 400Hz ? What are the advantages of this ?

Also, sorry Mike, I didn't mean to sound like a gawking tourist. Even though its been 20 years since I laid a wreath at the Arizona in Pearl its still very fresh in my memory.

A lot of military applications use 400Hz to save space and weight - the transformers are a lot lighter.

If I recall, the big honking plugs were called "Joy" connectors. I think it was the manufacurer's name. I was on submarines, we pulled 4 400 amp 3phase cables into the escape trunk where the recepts were. Ours were threaded. You used a huge spanner wrench to turn them. Ugh. Bad memories.

The Navy used the 400hz sets on the computer systems. It was a method to speed up computing speed.

I know 400Hz is used on aircraft because xfmrs and motors need far less iron and copper, and this results in weight savings that in aviation applications are more important than the lower energy efficiency involved with such a high frequency.

I wasn't aware that 400Hz was used on ships. Space savings would seem to be a good reason.

It is not possible to get 400Hz from 60Hz using a rotary converter. They require different shaft speeds. If the second frequency is a multiple or submultiple of the first, you can use a shaft or a direct drive motor-generator (well, after adjusting for the slip). I guess they must use belt- or gear-driven motor-generators, or VFDs, or something like that.

Any aviation workers out there?

[This message has been edited by yaktx (edited 02-01-2006).]

I occasionally need 400Hz power in the lab where I work. Converted from 60Hz by a special rotary converter made by Georator Corp.:
http://www.georator.com/ProductRotaryMotorGenerator.php

The company in that link appears to disagree with that statement.

The first unit shown is indeed a belt drive, but the next *one is common shaft*.

I recall that a while back someone invented a motor/generator with "rewritable poles", in other words, through some sort of control it was able to shift the magnetic location of its poles actively while running. I'll try to dredge up a link...

edited text between *, the last item on the linked page is actually a line isolator.

[This message has been edited by mxslick (edited 02-02-2006).]

Fascinating... it has an induction motor, but will produce 400Hz from either 50 or 60Hz? How is this possible? If you had a universal or permanent-magnet motor, you could vary the motor speed, but induction?

Written-pole motors... yeah, I've heard of those. Never seen one, though. I read on the web where they are being used in irrigation, since you can get them in just about any Hp and they run on single phase.

[This message has been edited by yaktx (edited 02-02-2006).]