How frequency effects voltage

Unfortunately not every problem is solved by plugging numbers into a formula. Your question is a good one but you need to do some studying on the way higher frequency AC behaves in transmission lines and in every day inductors like drills, mixers, etc. You may find some interest in Edison's proposal to feed the world power with DC and what some rebuttals to this entailed. Good question, take a fun journey. Regards, Tom

There are quite a few different factors to consider when deciding on the "best" power distribution frequency. In general, the transformer core size goes up proportional to the inverse of the frequency. So

400 Hz transformers are about 60/400=15% the size of those for 60 Hz. This is an economic advantage for the higher frequency. But the core loss goes up as the frequency does, in two ways. There are eddy current losses (current that circulates in the core as if it were a short circuited transformer secondary) that can be reduced by making the laminations of higher resistivity material (most commonly, by alloying silicon with iron) and by making it of stacks of insulated laminations that are proportionately thinner.

There are also per cycle losses related to the energy lost each time you reverse the direction of magnetization in iron, called hysteresis losses. There is nothing you can do about those, as long as you use iron for the core material. The exotic core materials with much lower hysteresis losses are a lot more expensive than the silicon iron alloy used for 60 Hz transformers.

There is also the problem of phase shifts over distance that gets worse in proportion to the frequency. A wavelength at 60 Hz is something like 3100 miles. At 400 Hz, that drops to about 470 miles. You get into huge problems trying to connect a vast network of generators and consumers with transmission lines when there are waves of many phases propagating around all possible loops of the system, some places aiding and some places canceling (called standing waves). This makes it almost impossible to build a system with multiple redundant energy paths, to handle all sorts of load shifts and equipment failures. In effect, each state or city would have to have its own independent 400 Hz grid.

I think those are the biggest factors in favor of lower frequency transmission of power. There are quite a few more second and third order factors, some of which may have applied more at the origin of the grid than they might, now, with advances in technology.

Motors. A 24,000 RPM induction motor would be hard to handle.

John

use 50/60 Hertz in houses why we dont use 400Hertz. i

frequency losses increase but what is formula or

Unfortunately not every problem is solved by plugging numbers into a formula. Your question is a good one but you need to do some studying on the way higher frequency AC behaves in transmission lines and in every day inductors like drills, mixers, etc. You may find some interest in Edison's proposal to feed the world power with DC and what some rebuttals to this entailed. Good question, take a fun journey. Regards, Tom[/quote:dafa126be6] Just a passing thought about Edison's world power feeds. There are instances now where high voltage is being carried as DC on the grid. It is used where countries with different frequency standards consume each other's electricity, and because it is now becoming cost effective because for a given maximum voltage, DC can carry about 40% more power than AC of the same peak voltage.

Why does the military use 400Hz?

Bill, Phoenix

But all the transformers up on the poles would go

hhhhmmmmmmmmmmmmmmmmmmmm...

John

But also very useful for some applications. You can make them run slower at the cost of more poles.

They do that now. At 400 Hz they go WHEEEEEEEEEEEEEEEE.

Have worked in a place with 400Hz(military complex), wel you wont like it . The facility was drenched in audible harmonics,

1200 Hz (3rd harmonic) being particulary audible. People working there for 10+ years had permanent damage in their hearing curve, and did not hear that frequency anymore. So no, dont do it.

To save weight , especially in the aircraft. Sometimes on the stuff that has to be carried on the backs of the ground forces.

Generators too !

Graham

Airforce facility, airforce equipment, and a bit of stupidity perhaps?? They had a huge flywheel/moto/dynamo/diesel running for conversion and emergency power.

That would be hard to take, having the distribution trannys "Whee"ing all over folks !!

--
Regards ......... Rheilly Phoull

Airplanes.

The transformers are smaller, and the engine usually revs so high that generating 400Hz is trivial.

I _have_ always wondered, though, if they really have that box of dirt in the tail section for "ground". ;-P

Cheers! Rich

There is no as such the equation for frequency effect on domestic distribution system. But yes, if we are going to use the devices which differ form power frequency ( 50 Hz) at rated voltages ( 230 / 240 Volts), then this will unnecessarily heat up the core of electric machines ( viz Motors, compressors of refrigerators, COres of transformers used in that circle etc).As far as usage of electronic devices is concerend since they are of relatively low power level, the effect would not be significant.

Hope it is clear.

M.S.Chaitanya.

Hi list, I think the electronics part of ur reply is not valid MR. Chaitanya.Actually the components of any ckt(electrical/electronic) have a tolerance limit.The rate at which they can react to application of voltages or rate of change of current across them.Hence almost all the components that are currently designed for 50/60hz would choke down and hence most of the ckts simply won't react so fast.Resulting in very fast friction at molecular level,and hence huge amt of heat dessipation.Hence we need to redesign our ckts.Hope the answer was clear.

Open to comments.

-kk