Transformer inrush current

[tonymagona334]

if there was anything that could describe how i wake up, it's this.

[tonymagona334]

i want to see a transformer going offline, that would be cool to see for a change

[RODALCO2007]

@tonymagona334 Will do.

[PKYTirl]

The soothing sound of 50Hz

[theduke502]

@RODALCO2007 Just a question for you. What cause that "growling" sound?

[RODALCO2007]

@theduke502 It is the magnetic stress on the laminations of the core. The soft iron laminations are magnetised and demagnetised 50 or 60 times per second.

[theduke502]

@RODALCO2007 Hm, very interesting. Thank you for your reply. I'm fascinated by things like this :)

[thewii552]

@RODALCO2007 i like the sound of 50 hz hum than 60. And I am in north america!

[douro20]

Yeah, higher frequencies are more efficient. They use 400Hz in aircraft.

[epd807]

NICE! I love the 50Hz growl.  You have the best on the net! Keep em coming! Thanks!

[RODALCO2007]

@epd807 Thank you

[WackyAmoebatrons]

@epd807 What you hear is very likely not 50Hz, but 100Hz because the mechanic pressure being exerted on various metal parts in the transformer is proportional to the magnitude (or even its square) of the magnetic field strength. Because the magnitude goes from 0 to max twice per period, the frequency is doubled.

[quantumbits]

@WackyAmoebatrons Of course it is three phase... Three different windings reaching peak at three different times. So 150 and 300 Hz ?

[WackyAmoebatrons]

@quantumbits I hesitate to answer this in the affirmative. The 3 phases are transformed in separate transformer rings, each of which vibrating at 100Hz, but with a 120 degree phase shift. I'm not sure if a human ear and brain would turn this into a frequency tripled sensation. But then, the wavelength at 100Hz is 3m, which is about the dimension of a transformer so it might be possible. We'd have to conduct an experiment, placing a sound generator next to the transformer and match frequencies.

[BurtBartlow]

Excellent.

[MrGerbilBrain]

I have a power-amplifier power transformer that goes BUZzzzzzzzz when it is powered up without a soft-start circuit.

[Redneckology]

50hz just sounds more evil. I love it.

[67tr876]

I love the sound of 50hz ! its so low unlike what i hear all the time 60hz but i like both. Tell me do Motors run better on 60hz ?

[hugestomper]

@67tr876 a 2pole motor runs 300 rpm on 50hz and 3600 on 60hz

[67tr876]

@hugestomper i see but why wont the UK or places that use 50hz go over to 60hz ? would it hurt motors and lights ? i think it would . btw thanks for the info

[TheWelly888]

@67tr876 UK power station alternators are all producing 50Hz, it is simply not practical to speed them up to produce 60Hz. Also a lot of equipment are designed to work optimally at 50Hz AC rather than 60Hz.

[hugestomper]

@67tr876 sorry "3000 rpm"

[coolbluelights]

@67tr876 induction motors run faster on 60 Hz

[MadManMarkAu]

@67tr876 Also, some old clocks used to use the 50Hz mains supply as a clock signal to keep themselves on time. I believe some are still in use today. The power station was never dead on 50Hz, it wandered throughout the day, but they sped up/slowed down each day so the total cycles per day remained the same.

[RODALCO2007]

@MadManMarkAu Correct, most mains driven clocks rely on the mains frequency.

[Nivicoman]

@RODALCO2007 I wonder how the gear trains are calculated as 50 does not evenly divide into 60. I would think that a 60 Hz clock would have a motor spinning 1 turn each cycle so dividing by 60 the correct number of times will result in 1 revolution per minute and 1 per hour respectively.

50 revolutions per second, how does that result in 1 rev/min/hour?50/60 = 0.833333333333...the gear ratios would never be even. There must be a way that it is made to work that I'm not seeing.

[ddanielmiester]

@Nivicoman Not 50rev/s, more like 5rev/sec.

Also, as long as the number can be expressed as a whole number over another whole number, a gearbox can be made.

[RODALCO2007]

@67tr876 a 60 Hz system is actually more efficient.

[code123ns]

@RODALCO2007 Actually, it depends on the use. Sometimes DC is most efficent, sometimes 50, 60 or 400 Hz

[JetMechMA]

@code123ns They use 400 Hz in aircraft and I think it is because you can use thinner gauge wires which are lighter in weight which has obvious benefits in airplanes.

[code123ns]

@JetMechMA yes, and you need smaller transformers. It's also used in ground based mobile radars and some other equipment.

Choosing parameters of a system is an optimization task that takes all sorts of inputs that reflect the needs and available resources (material cost, weight, transmition distance, dominant use, ...). Saying that a system is more efficient based on just one of the parameters is shallow and pedantic (:D). Also note that over time, those variables may change.

[code123ns]

@JetMechMA yes, and you need smaller transformers. It's also used in ground based mobile radars and some other equipment.

Choosing parameters of a system is an optimization task that takes all sorts of inputs that reflect the needs and available resources (material cost, weight, transmition distance, dominant use, ...). Saying that a system is more efficient based on just one of the parameters is shallow and pedantic (:D). Also note that over time, those variables may change.

[captain150]

@RODALCO2007 Ideally, the single world standard would be 240v / 60hz. That would be the best.

[RODALCO2007]

@captain150 Correct, I think some countries in South America have 240V 60Hz.

Basically the USA has 240 V 60Hz, although most smaller appliances there run on 110 / 120 V, ranges and airco on 240 V 60 Hz.