400 Hertz

[muskrat]

I know one of you fine people mentioned working on an AF base, but does anyone know about U/L listing or anything else about 208Y/120 at 400 htz? Any isues about heat or whatever when using or connecting to it?

Thanx

 

[LarryFine]

Simply, the higher frequency allows for most equipment to run cooler, or for the same rating to be physically smaller and lighter.

In case you you (or anyone else) need it, I have a 400Hz phase rotation direction tester I have no use for, a Knopp K-6.

 

[beanland]

400Hz

400Hz

The essence of 400Hz is that the power that you can transform through a transformer is proportional to the frequency. A 400Hz transformer is a lot smaller than the same 60Hz kVA-rated transformer. That means weight and size. However, 400Hz has a shorter wavelength so has more impedance issues since reactance is a function of inductance and frequency. 400Hz is found on ships and some aircraft.

BTW 133Hz was also a common frequency for power before 50/60Hz became standard.

 

[G._S._Ohm]

The skin effect will worse than at 60 Hz.

 

[iwire]

Simply, the higher frequency allows for most equipment to run cooler, or for the same rating to be physically smaller and lighter.

Nice features when fitting out an airplane.

 

[petersonra]

The skin effect will worse than at 60 Hz.

It depends on the wire size. for smaller wires, the difference is not significant.

IIRC, wire sizes below 1/0 are generally OK at 400 Hz.

Square D has data for the CBs and panelboards for these frequencies.

Be advised that the interrupting capacity of CBs is much lower than at 60 Hz.

Use non-ferrous conduit and/or cable tray.

 

[muskrat]

Thanx all for the responses so far. This is going to be a feeder to an EPU that converts 480 3ph delta/grounded-b at 60 hz to 120/208Y 4 wire at 400hz. run +/- 20' to 4 pole transfere sw/ with other source their genny's then feeding radome. Gen and radar cord connected.(ie no distance)

Thanks L. Fine, they have the meters.

 

[LarryFine]

Nice features when fitting out an airplane.

Well, it ain't rocket surgery, y'know.