efficiencies of appliance 3-phase brushless motors?

[danny burstein]

In <cbgh3e9lgca6v3gjvhi8fk2614cfu8q59j@4ax.com> default <default@defaulter.net> writes:

Annoyingly, though, Lucky Goldstar is only offering a couple
of models in the US, with ratings in the 14,000 BTU range.

I wrote to them asking if they'd please consider selling
smaller, like 5 to 10,000 ones. Not at this time...

Since they do run the compressor slower as cooling needs are met, you
probably shouldn't look at an inverter AC the same as you would a
standard AC. If you need 10,000 BTU a 14,000 btu will throttle back
to around 20% of the power a 14K would require and that would still be
less than the 10K would use.

Oh, absoposolutely. But there's still the size, material,
and cost waste...

Of course I found these units two weeks _after_ I picked
up and installed the traditional ones in our house...


--
_____________________________________________________
Knowledge may be power, but communications is the key
dannyb@panix.com
[to foil spammers, my address has been double rot-13 encoded]

 

On Friday, January 11, 2019 at 8:30:07 AM UTC-8, default wrote:

On Fri, 11 Jan 2019 14:21:27 +0000 (UTC), danny burstein
dannyb@panix.com> wrote:

In <ec417b1c-18c8-4f85-8284-662e712c23b1@googlegroups.com> mrdarrett@gmail.com writes:

On Thursday, January 10, 2019 at 6:41:12 PM UTC-8, danny burstein wrote:
In <3iqf3ehsptonbtlf27vd0nqqptq6dd2um3@4ax.com> default <default@defaulter.net> writes:

Lots of air conditioners are moving to speed controlled three phase
compressor motors these days. They've been in use for large
commercial AC's for awhile now, and plenty of the newer heat pumps use
them. There's at least one window unit that uses a VFD and three
phase motor.

Dunno about it being three phase, but here you go:

http://www.lg.com/us/air-conditioners/lg-LW1517IVSM

Oh neato! Even better; it's Brushless DC (BLDC)!

"... thanks to LG's unique BLDC motor and dual inverter compressor..."

Annoyingly, though, Lucky Goldstar is only offering a couple
of models in the US, with ratings in the 14,000 BTU range.

I wrote to them asking if they'd please consider selling
smaller, like 5 to 10,000 ones. Not at this time...

Since they do run the compressor slower as cooling needs are met, you
probably shouldn't look at an inverter AC the same as you would a
standard AC. If you need 10,000 BTU a 14,000 btu will throttle back
to around 20% of the power a 14K would require and that would still be
less than the 10K would use.

Of course if 5K (does anyone make one that small?) does the trick, 14K
would be way over-kill.

With standard AC units the best savings meant using the smallest AC
that would do the job. Presumably you could live with the longer time
to cool-down... and maybe there'd be a couple of days each year when
the temp/humidity was so high that it might not keep up with your
needs. These inverter type units are a game-changer in that respect.
And they soft-start, so you aren't pulling 40 amps to get the
compressor turning over from a dead stop.

Home Depot has a 5kbtu window AC unit for around $100 or $130; I forget exactly.

I went ahead and took apart my broken Sears/Kenmore front load washing machine (turns out it has broken shocks, among other problems) and pulled out the motor. It's a J52AAC-0102 if anyone's curious.

I was about to ask if anyone knows of circuits to play with 3-phase motors but I found something already.

https://hackaday.com/2012/01/19/building-a-variable-frequency-drive-for-a-three-phase-motor/

http://blog.hardcore.lt/mic/driver-schematics.png

Unfortunately that MC3PHAC controller is at End Of Life due to low sales.

Michael

 

[default]

On Fri, 11 Jan 2019 10:34:01 -0800 (PST), mrdarrett@gmail.com wrote:

On Friday, January 11, 2019 at 8:30:07 AM UTC-8, default wrote:
On Fri, 11 Jan 2019 14:21:27 +0000 (UTC), danny burstein
dannyb@panix.com> wrote:

In <ec417b1c-18c8-4f85-8284-662e712c23b1@googlegroups.com> mrdarrett@gmail.com writes:

On Thursday, January 10, 2019 at 6:41:12 PM UTC-8, danny burstein wrote:
In <3iqf3ehsptonbtlf27vd0nqqptq6dd2um3@4ax.com> default <default@defaulter.net> writes:

Lots of air conditioners are moving to speed controlled three phase
compressor motors these days. They've been in use for large
commercial AC's for awhile now, and plenty of the newer heat pumps use
them. There's at least one window unit that uses a VFD and three
phase motor.

Dunno about it being three phase, but here you go:

http://www.lg.com/us/air-conditioners/lg-LW1517IVSM

Oh neato! Even better; it's Brushless DC (BLDC)!

"... thanks to LG's unique BLDC motor and dual inverter compressor..."

Annoyingly, though, Lucky Goldstar is only offering a couple
of models in the US, with ratings in the 14,000 BTU range.

I wrote to them asking if they'd please consider selling
smaller, like 5 to 10,000 ones. Not at this time...

Since they do run the compressor slower as cooling needs are met, you
probably shouldn't look at an inverter AC the same as you would a
standard AC. If you need 10,000 BTU a 14,000 btu will throttle back
to around 20% of the power a 14K would require and that would still be
less than the 10K would use.

Of course if 5K (does anyone make one that small?) does the trick, 14K
would be way over-kill.

With standard AC units the best savings meant using the smallest AC
that would do the job. Presumably you could live with the longer time
to cool-down... and maybe there'd be a couple of days each year when
the temp/humidity was so high that it might not keep up with your
needs. These inverter type units are a game-changer in that respect.
And they soft-start, so you aren't pulling 40 amps to get the
compressor turning over from a dead stop.


Home Depot has a 5kbtu window AC unit for around $100 or $130; I forget exactly.

I went ahead and took apart my broken Sears/Kenmore front load washing machine (turns out it has broken shocks, among other problems) and pulled out the motor. It's a J52AAC-0102 if anyone's curious.

I was about to ask if anyone knows of circuits to play with 3-phase motors but I found something already.

https://hackaday.com/2012/01/19/building-a-variable-frequency-drive-for-a-three-phase-motor/

http://blog.hardcore.lt/mic/driver-schematics.png

Unfortunately that MC3PHAC controller is at End Of Life due to low sales.

Michael

Ebay has some cheap VFD controllers starting at ~$50 (for 220VAC)
Single phase in, three phase out.

 

[Ralph Mowery]

In article <3iqf3ehsptonbtlf27vd0nqqptq6dd2um3@4ax.com>,
default@defaulter.net says...

Lots of air conditioners are moving to speed controlled three phase
compressor motors these days. They've been in use for large
commercial AC's for awhile now, and plenty of the newer heat pumps use
them. There's at least one window unit that uses a VFD and three
phase motor.

At least 10 or more years ago the heat pumps and probably other
heating/cooling systems moved to speed controlled motors. There is a
way where the motors start up slow to move the air that is sort of a way
to cheat on the 'government efficency' numbers.

 

[Ralph Mowery]

In article <b2ch3e5co7auvip27jsmtcc141gn80l905@4ax.com>,
default@defaulter.net says...

I built a small deck out some scraps of treated lumber to keep it off
the ground, but they sell brackets so you can mount the compressor on
the side of the house or put in on a small slab. I did not pump down
the system with a vacuum (the pump and gauges would have cost $350).
Instead I purged it with the pre-charged gas that was already in the
compressor unit - let it leak for a few seconds until the refrigerant
displaced the air in the lines. (they claim you need a vacuum pump in
the ads, but had instructions for purging in the literature that
shipped with it) It has been working like a champ for ~16 years now
so I guess purging works.

It is not so much if purging works or not. For around 20 or 30 years it
has been illegal to dump any refrigerent into the atmosphere. The claim
by the government is that it depleats the ozone layer. There is a big
fine for doing that.

 

[default]

On Fri, 11 Jan 2019 17:59:02 -0500, Ralph Mowery
<rmowery28146@earthlink.net> wrote:

In article <b2ch3e5co7auvip27jsmtcc141gn80l905@4ax.com>,
default@defaulter.net says...
I built a small deck out some scraps of treated lumber to keep it off
the ground, but they sell brackets so you can mount the compressor on
the side of the house or put in on a small slab. I did not pump down
the system with a vacuum (the pump and gauges would have cost $350).
Instead I purged it with the pre-charged gas that was already in the
compressor unit - let it leak for a few seconds until the refrigerant
displaced the air in the lines. (they claim you need a vacuum pump in
the ads, but had instructions for purging in the literature that
shipped with it) It has been working like a champ for ~16 years now
so I guess purging works.



It is not so much if purging works or not. For around 20 or 30 years it
has been illegal to dump any refrigerent into the atmosphere. The claim
by the government is that it depleats the ozone layer. There is a big
fine for doing that.

The R134a refrigerant can be bought by anyone and they sell one pound
cans for recharging car AC's. Or you can go on-line and order a 30 lb
cylinder without a license. (unlike R-30)

The info I found said it was a greenhouse gas, but not ozone
depleting. The information that shipped with it gave the reason for
purging to be: moisture freezing in the evaporator valve and blocking
it. (the "valve" is often just a length of copper capillary tubing)
The AC people said it is necessary to prevent acids from forming and
destroying the compressor.

I've no doubt that it is better to recycle it, and better to draw all
the moisture and air out with a pump. But given the number of cars on
the road leaking it by the pound, I figure my one-time loss of an
ounce or two shouldn't matter.

AND if you still want to say it is wrong, read the label on a can of
computer "Dust-Off." There are people on Utoobe who buy that stuff
because it is cheaper than the same stuff labeled as a refrigerant.

The units do have desiccant dryers in the compressors to eliminate
moisture.

Back in the day... the EPA forced AC contractors to buy some pretty
damn expensive refrigerant recovery equipment, to deal with the hassle
of sending it off to be recycled into fresh clean stuff, and to take
classes to learn the law and how to recycle to get a license. That
same regulation is capitalized by AC contractors today that see
DIYer's cutting into profits that they think are rightfully theirs.
Now it is political, cans of "dust-off" not withstanding. The other
faction with a vested interest are the thousands of auto-repair
businesses who don't want to spend the money on specialized equipment
or hire specialists to work on AC.

 

[default]

On Fri, 11 Jan 2019 17:51:42 -0500, Ralph Mowery
<rmowery28146@earthlink.net> wrote:

In article <3iqf3ehsptonbtlf27vd0nqqptq6dd2um3@4ax.com>,
default@defaulter.net says...

Lots of air conditioners are moving to speed controlled three phase
compressor motors these days. They've been in use for large
commercial AC's for awhile now, and plenty of the newer heat pumps use
them. There's at least one window unit that uses a VFD and three
phase motor.



At least 10 or more years ago the heat pumps and probably other
heating/cooling systems moved to speed controlled motors. There is a
way where the motors start up slow to move the air that is sort of a way
to cheat on the 'government efficency' numbers.

Huh? That doesn't sound believable. An AC runs and uses power which
is easily measured in watts, can be used to cool water or air which
have known caloric absorption rates for measurable temperature
rise/fall... which, in turn, can be used to calculate power doing
useful work.

That is how microwave ovens are tested for efficacy. How much
temperature rise in a known quantity of water is produced in a
specific amount of time. An AC is playing the same game, and the same
measuring techniques can be used to test efficiency. The testing
equipment would cost a little more.

Soft start is generally just easier on the mechanical components and
eliminates the large power spike starting induction motors create.
Eliminates the centrifugal switches, and is easier on the power source
(wiring and circuit breakers)

Soft start can also provide feedback in AC systems to avoid
overloading compressors with a lot of back-pressure when starting.
(eliminating the pressure switches or thermal overloads AC's and
refrigerators currently use)

Are you sure you aren't confusing this with Auto computers programmed
to run lean in testing but richer in normal driving?