I seem to have been corrected. The chosen frequencies were related to some laws of physics, but more on what kind of generator was available instead of how the frequency acted when connected to a distribution grid consisting of miles or wiring.

I have seen a 5 HP 400 Hz motor that you can hold in one hand. That made me wonder why anybody would choose 50 Hz or 60 Hz. I see there are a lot of reasons.

IIRC; 400Hz was pretty much the standard in aircraft electrical systems.

 

IIRC; 400Hz was pretty much the standard in aircraft electrical systems.

True. Probably the main reason a 5HP motor was available in that frequency.

 

IIRC; 400Hz was pretty much the standard in aircraft electrical systems.

Wasn't that to reduce the size/weight of electromagnetic devices?
Max.

 

Wasn't that to reduce the size/weight of electromagnetic devices?
Max.

It sure accomplished that, even if it wasn't the intent.

 

400Hz in aircraft devices.

 

A list for the mains power system of the world.
Mains electricity by country.

 

I heard someone in the US decided on 60 Hz because they felt it was the best compromise between having oversized transformers and power loss in transmission lines. Later when Europe was electrified they chose 50 Hz because it fit into the metric system where they like things to be multiples of 5 or 10.

 

Later when Europe was electrified they chose 50 Hz because it fit into the metric system where they like things to be multiples of 5 or 10.

UK (50Hz) was not metric until 1965!
Max.

 

UK (50Hz) was not metric until 1965!

Ok well like I said "thats what I _heard_"

 

There is a fair amount of info here: http://en.wikipedia.org/wiki/Utility_frequency
Reminder that Japan has 100 V as well as 60 and 50 Hz

If we were doing home electricity today, we might have an entirely different solution. We might have a low voltage DC bus for that matter and a high voltage bus for appliances.

I suppose the US thought that 120 V to ground was "safer". It's fare, but some homes can have 3 phase power. 3 phase is more efficient for motors, but now, your dryer and furnace could e a VFD. Single phase initially, but converted to 3 phase in the controller.

In US homes, appliances like the dishwasher, electric dryer, all electtrc stove, electric water heater, HVAC system are 240. In fact, it's been only recent that dryers have been wired the way they should be. What hasn't been done is the proper use of 3 or 4 pole 240 V. i.e. L1, L2, G and L1, L2, N and G.

Otherwise you have up to 20 A of 120 V, but if on more than 3 hours/day (defined as continuous) the load needs to be reduced to 80% of 20 A.

The US has now created what's called a "tamper-proof" outlet where both sides must be pressed simultaneously to allow plug insertion. Read as"kid-proof"/

Regulations have added AFCI's and GFCIs to the mix of protective devices and, in general, your grandfathered or you don't have to upgrade unless substantial renovations are done.

Even now, some "automation devices" require a neutral in the "switch side" which we don't normally have.\

A consequence of our poorly designed 120 V receptacles, Wall wart power supplies have trouble being reliable.

 

Some furnaces already are VFD. Google X-13 motor. They cost $464 wholesale for a 1/3 hp motor. When installed by an authorized dealer, 1/3 HP will cost you $1500 and their average lifespan is 3 years. (Must have more microprocessors!)

I disagree with the idea that wall warts fail because the recepticals are poorly designed. The only damage I have ever seen on an American receptical was cracks in the front plastic, and they still worked electrically.

 

If we were doing home electricity today, we might have an entirely different solution. We might have a low voltage DC bus for that matter and a high voltage bus for appliances.

you cant really "move" joules under DC. so you would want poco to do service entrance rectification??

 

Some furnaces already are VFD. Google X-13 motor. .

Yes the GE ECM (Electronically Commutated 3ph Motor) HVAC motor has been around for a while http://www.gotoevo.com/GEMotors.htm
Also the 3ph Outrunner is now used in most washing machines http://www.fp.fisherpaykel.com/direct-drive-motors/
Max.

 

Soon we can all have several high efficiency motors that cost $1500 each to be replaced every 3 years.
We're going to save so much money on our electric bills!

 

UK (50Hz) was not metric until 1965!
Max.

I've been reading an archive of Wireless World that starts from the first issue in 1913.

Metric measurements had started to creep in even before WW2.

There were a couple of changes of standards over the years, adoption of SI units was relatively recent.

 

Soon we can all have several high efficiency motors that cost $1500 each to be replaced every 3 years.
We're going to save so much money on our electric bills!

The ECM Washing M/C outrunner you can buy the wound stator or the rotor separately. $130.00 & $90.00!
Max.

 

The ECM Washing M/C outrunner you can buy the wound stator or the rotor separately. $130.00 & $90.00!
Max.

Yebbut...what's the price for the control section?
I dropped a perfectly good rotor and stator in the trash because the driver failed and I could only buy the whole motor. Why? Because the manufacturer programs in the speed and it's a secret.

 

I dropped a perfectly good rotor and stator in the trash because the driver failed and I could only buy the whole motor. Why? Because the manufacturer programs in the speed and it's a secret.

I am trying to get hold of a defective GE ECM (HVAC fan etc) to try and reverse engineer a drive, from what I have seen so far they appear to be sensorless, there only appears to be 3 conductors from board to windings, I do not see any hall sensors etc for commutation?
Can you or anyone confirm it?
Max.