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On the other side of the pond with 600V Canadian equipment/motors you get the opposite effect. 60Hz frequency is the same but the 480V supply voltage is too low. This leaves an under fluxed motor.

Again depending on load type this may or may not be a problem. Under fluxed motors can run for years if their not loaded to their maximum ratings. If the power output is not great enough for the load, then the process suffers or the motor overheats and gives up.
 

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Electron Factory.Worker
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You’ll notice that MV voltages typically jump in multiples of sqrt(3).

2.4kv -> 4.16kv -> 7.2kv -> 12.47kv -> 21.6kv

One of the reasons for this is that it gives you more flexibility with your transformers. A transformer 7.2kv transformer can be fed with 7.2kv in delta or 12.47kv in a wye configuration.

generators are typically 13.8kv. I’ve been told it’s the highest practical voltage before corona becomes an issue and more expensive insulating systems are required.
 

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600v 3 phase services are common but fairly often we’ll end up stepping down for 480v American machines. Last year I did a 400v electric still that was Dutch in origin if I remember right.
 

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Bilge Rat
motors and controls.........
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Another one is big planes usually have both 24DC and 115AC 3Ø 400HZ systems.

I don't know about now but years ago, airports had motor-generator sets for ground power. They had a 60HZ motor driving a 400HZ generator that provided power to the plane when it was on the ground.
 

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Discussion Starter · #25 ·
I didn't even think of the 400hz airplane systems. I've never been around them, just read about them. The other electrician I work with worked around them some in the navy. I never really realized they were 3 phase systems. The higher frequency is for smaller wire for reduced weight?
 

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Bilge Rat
motors and controls.........
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I didn't even think of the 400hz airplane systems. I've never been around them, just read about them. The other electrician I work with worked around them some in the navy. I never really realized they were 3 phase systems. The higher frequency is for smaller wire for reduced weight?
The 115AC systems on the planes that I'm familiar with are ∆ with a ground fault detector, actually, several ground fault detectors. They have several busses, usually all connected together but if you get a ground fault, you can isolate stuff until you find the bad one.

400HZ motors are a lot smaller than 60HZ ones, a 10HP 400HZ motor is about the size and weight of a 1HP 60HZ model. Same with generators. On planes, weight is very important.

Also, system redundancy is vital, each engine has both a 24DC and a 115AC fuel pump. On a 2 engine plane, one engine uses the 24DC pump and the other engine uses the 115AC one. On a 3 engine plane, the middle engine normally uses the AC pump and the other 2 use the DC pumps. A 4 engine plane will have #1 & #3 on AC and #2 & #4 on DC. This way, if one electrical system fails, it doesn't kill all the engines.

Same thing with all those fancy gauges and dials and stuff up in the front office, one side is AC the other is DC.
 
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