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D

default

Guest
I have an older window air conditioner that I\'d like to hang on to for
a few more years. The name plate says it is 220 VAC and since the
power company went through and upgraded the distribution network and
replaced HT and transformers my service which had been running 210-220
volts is now a steady 250 volts and my bill is up ~15%.

The increased consumption is tied to how much I run the AC and since
the upgrade I\'ve already had to replace both the compressor and fan
motor run caps. The compressor one died a quiet death, and the fan
cap melted and smoked. The compressor cap went out the week they
changed the transformer and the fan cap about a month later. I put in
higher voltage ones and the AC is back on line.

I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
power transformer, wired to buck the voltage makes any sense?
 
G

George Herold

Guest
On Monday, July 13, 2020 at 11:31:34 AM UTC-4, default wrote:
I have an older window air conditioner that I\'d like to hang on to for
a few more years. The name plate says it is 220 VAC and since the
power company went through and upgraded the distribution network and
replaced HT and transformers my service which had been running 210-220
volts is now a steady 250 volts and my bill is up ~15%.

The increased consumption is tied to how much I run the AC and since
the upgrade I\'ve already had to replace both the compressor and fan
motor run caps. The compressor one died a quiet death, and the fan
cap melted and smoked. The compressor cap went out the week they
changed the transformer and the fan cap about a month later. I put in
higher voltage ones and the AC is back on line.

I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
power transformer, wired to buck the voltage makes any sense?
How about a variac to lower the voltage. (kinda spendy...
might be better to invest in new AC unit.)

George H.
 
G

George Herold

Guest
On Monday, July 13, 2020 at 11:31:34 AM UTC-4, default wrote:
I have an older window air conditioner that I\'d like to hang on to for
a few more years. The name plate says it is 220 VAC and since the
power company went through and upgraded the distribution network and
replaced HT and transformers my service which had been running 210-220
volts is now a steady 250 volts and my bill is up ~15%.

The increased consumption is tied to how much I run the AC and since
the upgrade I\'ve already had to replace both the compressor and fan
motor run caps. The compressor one died a quiet death, and the fan
cap melted and smoked. The compressor cap went out the week they
changed the transformer and the fan cap about a month later. I put in
higher voltage ones and the AC is back on line.

I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
power transformer, wired to buck the voltage makes any sense?
How about a variac to lower the voltage. (kinda spendy...
might be better to invest in new AC unit.)

George H.
 
D

default

Guest
On Mon, 13 Jul 2020 08:47:27 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

On Monday, July 13, 2020 at 11:31:34 AM UTC-4, default wrote:
I have an older window air conditioner that I\'d like to hang on to for
a few more years. The name plate says it is 220 VAC and since the
power company went through and upgraded the distribution network and
replaced HT and transformers my service which had been running 210-220
volts is now a steady 250 volts and my bill is up ~15%.

The increased consumption is tied to how much I run the AC and since
the upgrade I\'ve already had to replace both the compressor and fan
motor run caps. The compressor one died a quiet death, and the fan
cap melted and smoked. The compressor cap went out the week they
changed the transformer and the fan cap about a month later. I put in
higher voltage ones and the AC is back on line.

I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
power transformer, wired to buck the voltage makes any sense?

How about a variac to lower the voltage. (kinda spendy...
might be better to invest in new AC unit.)

George H.
That would be ideal, but at a cost of ~$140 versus a transformer
costing ~$35.
 
D

default

Guest
On Mon, 13 Jul 2020 08:47:27 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

On Monday, July 13, 2020 at 11:31:34 AM UTC-4, default wrote:
I have an older window air conditioner that I\'d like to hang on to for
a few more years. The name plate says it is 220 VAC and since the
power company went through and upgraded the distribution network and
replaced HT and transformers my service which had been running 210-220
volts is now a steady 250 volts and my bill is up ~15%.

The increased consumption is tied to how much I run the AC and since
the upgrade I\'ve already had to replace both the compressor and fan
motor run caps. The compressor one died a quiet death, and the fan
cap melted and smoked. The compressor cap went out the week they
changed the transformer and the fan cap about a month later. I put in
higher voltage ones and the AC is back on line.

I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
power transformer, wired to buck the voltage makes any sense?

How about a variac to lower the voltage. (kinda spendy...
might be better to invest in new AC unit.)

George H.
That would be ideal, but at a cost of ~$140 versus a transformer
costing ~$35.
 
P

Pimpom

Guest
On 7/13/2020 11:25 PM, default wrote:
On Mon, 13 Jul 2020 08:47:27 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

On Monday, July 13, 2020 at 11:31:34 AM UTC-4, default wrote:
I have an older window air conditioner that I\'d like to hang on to for
a few more years. The name plate says it is 220 VAC and since the
power company went through and upgraded the distribution network and
replaced HT and transformers my service which had been running 210-220
volts is now a steady 250 volts and my bill is up ~15%.

The increased consumption is tied to how much I run the AC and since
the upgrade I\'ve already had to replace both the compressor and fan
motor run caps. The compressor one died a quiet death, and the fan
cap melted and smoked. The compressor cap went out the week they
changed the transformer and the fan cap about a month later. I put in
higher voltage ones and the AC is back on line.

I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
power transformer, wired to buck the voltage makes any sense?

How about a variac to lower the voltage. (kinda spendy...
might be better to invest in new AC unit.)

George H.

That would be ideal, but at a cost of ~$140 versus a transformer
costing ~$35.
I agree about the cost advantage of the variac/transformer. I was
about suggest a variac too but refreshed my newsreader before
hitting the Send button and saw that George had beaten me to it.

This reminds me of the time some 35 years ago when the power
supply in a friend\'s TV kept breaking down. It turned out that
the mains voltage in their house was persistently high. I
improvised a step-down autotransformer with a 12-0-12V 1A
transformer and fitted that inside the TV. It never broke down again.
 
P

Pimpom

Guest
On 7/13/2020 11:25 PM, default wrote:
On Mon, 13 Jul 2020 08:47:27 -0700 (PDT), George Herold
gherold@teachspin.com> wrote:

On Monday, July 13, 2020 at 11:31:34 AM UTC-4, default wrote:
I have an older window air conditioner that I\'d like to hang on to for
a few more years. The name plate says it is 220 VAC and since the
power company went through and upgraded the distribution network and
replaced HT and transformers my service which had been running 210-220
volts is now a steady 250 volts and my bill is up ~15%.

The increased consumption is tied to how much I run the AC and since
the upgrade I\'ve already had to replace both the compressor and fan
motor run caps. The compressor one died a quiet death, and the fan
cap melted and smoked. The compressor cap went out the week they
changed the transformer and the fan cap about a month later. I put in
higher voltage ones and the AC is back on line.

I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
power transformer, wired to buck the voltage makes any sense?

How about a variac to lower the voltage. (kinda spendy...
might be better to invest in new AC unit.)

George H.

That would be ideal, but at a cost of ~$140 versus a transformer
costing ~$35.
I agree about the cost advantage of the variac/transformer. I was
about suggest a variac too but refreshed my newsreader before
hitting the Send button and saw that George had beaten me to it.

This reminds me of the time some 35 years ago when the power
supply in a friend\'s TV kept breaking down. It turned out that
the mains voltage in their house was persistently high. I
improvised a step-down autotransformer with a 12-0-12V 1A
transformer and fitted that inside the TV. It never broke down again.
 
S

server

Guest
On Mon, 13 Jul 2020 11:31:30 -0400, default <default@defaulter.net>
wrote:

I have an older window air conditioner that I\'d like to hang on to for
a few more years. The name plate says it is 220 VAC and since the
power company went through and upgraded the distribution network and
replaced HT and transformers my service which had been running 210-220
volts is now a steady 250 volts and my bill is up ~15%.

The increased consumption is tied to how much I run the AC and since
the upgrade I\'ve already had to replace both the compressor and fan
motor run caps. The compressor one died a quiet death, and the fan
cap melted and smoked. The compressor cap went out the week they
changed the transformer and the fan cap about a month later. I put in
higher voltage ones and the AC is back on line.

I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
power transformer, wired to buck the voltage makes any sense?
Where I live we get 250 volts pretty steadily. In my shop are
several CNC machines, one of which cannot easily tolerate the 250
volts. So I use two buck/boost xmfrs wired in a particular buck
configuration to lower the 3 phase voltage going to that one machine.
Since doing so the machine has not once alarmede out due to over
voltage.
I also wired up a little 120 to 12 volt xmfr in buck configuration
to lower the 125 volts from the outlet to the 110 volts needed for a
tube amp.
There are directions online on how to select the proper sized xmfr
for the load it will be seeing and how to wire the thing in buck
configuration.
Eric
 
S

server

Guest
Your bill went up because of light bulbs and shit with heating elements, maybe the microwave if you use it alot, and of course if you have an electric stove.

Those types of motors usually run more efficiently on slightly higher voltage. Voltage up, current is the same or lower. Well power actually, it might be the same current but the phase changes the power factor. You pay by the watt, not the amp.
 
S

server

Guest
On Mon, 13 Jul 2020 11:31:30 -0400, default <default@defaulter.net>
wrote:

I have an older window air conditioner that I\'d like to hang on to for
a few more years. The name plate says it is 220 VAC and since the
power company went through and upgraded the distribution network and
replaced HT and transformers my service which had been running 210-220
volts is now a steady 250 volts and my bill is up ~15%.

The increased consumption is tied to how much I run the AC and since
the upgrade I\'ve already had to replace both the compressor and fan
motor run caps. The compressor one died a quiet death, and the fan
cap melted and smoked. The compressor cap went out the week they
changed the transformer and the fan cap about a month later. I put in
higher voltage ones and the AC is back on line.

I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
power transformer, wired to buck the voltage makes any sense?
Where I live we get 250 volts pretty steadily. In my shop are
several CNC machines, one of which cannot easily tolerate the 250
volts. So I use two buck/boost xmfrs wired in a particular buck
configuration to lower the 3 phase voltage going to that one machine.
Since doing so the machine has not once alarmede out due to over
voltage.
I also wired up a little 120 to 12 volt xmfr in buck configuration
to lower the 125 volts from the outlet to the 110 volts needed for a
tube amp.
There are directions online on how to select the proper sized xmfr
for the load it will be seeing and how to wire the thing in buck
configuration.
Eric
 
W

whit3rd

Guest
On Monday, July 13, 2020 at 8:31:34 AM UTC-7, default wrote:
I have an older window air conditioner that I\'d like to hang on to for
a few more years. The name plate says it is 220 VAC and since the
power company went through and upgraded the distribution network and
replaced HT and transformers my service which had been running 210-220
volts is now a steady 250 volts and my bill is up ~15%.
....
I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
power transformer, wired to buck the voltage makes any sense?
It doesn\'t make much sense to me; ask, instead, the power company to
adjust the line voltage to an acceptable value. The taps in their
transmission line drops are the solution to many such problems, if
they know that you have found an excessive voltage. I\'m not sure
250V average is excessive, but if there are peaks and dips...
 
W

whit3rd

Guest
On Monday, July 13, 2020 at 8:31:34 AM UTC-7, default wrote:
I have an older window air conditioner that I\'d like to hang on to for
a few more years. The name plate says it is 220 VAC and since the
power company went through and upgraded the distribution network and
replaced HT and transformers my service which had been running 210-220
volts is now a steady 250 volts and my bill is up ~15%.
....
I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
power transformer, wired to buck the voltage makes any sense?
It doesn\'t make much sense to me; ask, instead, the power company to
adjust the line voltage to an acceptable value. The taps in their
transmission line drops are the solution to many such problems, if
they know that you have found an excessive voltage. I\'m not sure
250V average is excessive, but if there are peaks and dips...
 
D

default

Guest
On Mon, 13 Jul 2020 16:49:33 -0700 (PDT), jurb6006@gmail.com wrote:

Your bill went up because of light bulbs and shit with heating elements, maybe the microwave if you use it alot, and of course if you have an electric stove.

Those types of motors usually run more efficiently on slightly higher voltage. Voltage up, current is the same or lower. Well power actually, it might be the same current but the phase changes the power factor. You pay by the watt, not the amp.
I think you are mistaken.

Some years ago I put a voltage stabilizer on a large fan. (adjustable
AC voltage regulator intended to be used for large motors) As I
adjusted the voltage lower the current dropped linearly until it
reached about 95 VAC then started rising exponentially as I dropped it
lower.

Torque of the motor may be dependent on voltage, but the torque
required for a refrigeration compressor varies with time. Starting up
with the system equilibrated, there\'s little back-pressure on the
compressor so it is lightly loaded, as back pressure builds the torque
necessary to maintain synchronous speed increases.

The only other change in my habits, I shower more with hot weather -
but use less hot water showering...

I still use 4 compact fluorescent bulbs in closets where they stay
off, every thing else is LED. I use the electric range less - in
summer.

I get a monthly report card from my power company with a graph of the
last 13 months. I normally track well below the average and below
their idea of what an energy efficient home should use. Last month I
was up to \"average.\" I believe it too. Years ago I mistakenly opened
my neighbors power bill (without looking at the addressee) and found
he was paying $120 when I was paying $30.
 
P

Phil Hobbs

Guest
On 2020-07-14 07:04, default wrote:
On Mon, 13 Jul 2020 16:49:33 -0700 (PDT), jurb6006@gmail.com wrote:

Your bill went up because of light bulbs and shit with heating elements, maybe the microwave if you use it alot, and of course if you have an electric stove.

Those types of motors usually run more efficiently on slightly higher voltage. Voltage up, current is the same or lower. Well power actually, it might be the same current but the phase changes the power factor. You pay by the watt, not the amp.


I think you are mistaken.

Some years ago I put a voltage stabilizer on a large fan. (adjustable
AC voltage regulator intended to be used for large motors) As I
adjusted the voltage lower the current dropped linearly until it
reached about 95 VAC then started rising exponentially as I dropped it
lower.

Torque of the motor may be dependent on voltage, but the torque
required for a refrigeration compressor varies with time. Starting up
with the system equilibrated, there\'s little back-pressure on the
compressor so it is lightly loaded, as back pressure builds the torque
necessary to maintain synchronous speed increases.
snip
But if you have a momentary power dropout, it has to restart into the
full back-pressure of the evaporator. If the A/C isn\'t a tiny one, I
sure wouldn\'t be mickey-mousing anything that would increase the mains
impedance.

Electrical codes contain a lot of non-obvious and very expensive wisdom.

Cheers

Phil Hobbs




--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
D

default

Guest
On Mon, 13 Jul 2020 16:49:33 -0700 (PDT), jurb6006@gmail.com wrote:

Your bill went up because of light bulbs and shit with heating elements, maybe the microwave if you use it alot, and of course if you have an electric stove.

Those types of motors usually run more efficiently on slightly higher voltage. Voltage up, current is the same or lower. Well power actually, it might be the same current but the phase changes the power factor. You pay by the watt, not the amp.
I think you are mistaken.

Some years ago I put a voltage stabilizer on a large fan. (adjustable
AC voltage regulator intended to be used for large motors) As I
adjusted the voltage lower the current dropped linearly until it
reached about 95 VAC then started rising exponentially as I dropped it
lower.

Torque of the motor may be dependent on voltage, but the torque
required for a refrigeration compressor varies with time. Starting up
with the system equilibrated, there\'s little back-pressure on the
compressor so it is lightly loaded, as back pressure builds the torque
necessary to maintain synchronous speed increases.

The only other change in my habits, I shower more with hot weather -
but use less hot water showering...

I still use 4 compact fluorescent bulbs in closets where they stay
off, every thing else is LED. I use the electric range less - in
summer.

I get a monthly report card from my power company with a graph of the
last 13 months. I normally track well below the average and below
their idea of what an energy efficient home should use. Last month I
was up to \"average.\" I believe it too. Years ago I mistakenly opened
my neighbors power bill (without looking at the addressee) and found
he was paying $120 when I was paying $30.
 
D

default

Guest
On Tue, 14 Jul 2020 09:07:33 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-07-14 07:04, default wrote:
On Mon, 13 Jul 2020 16:49:33 -0700 (PDT), jurb6006@gmail.com wrote:

Your bill went up because of light bulbs and shit with heating elements, maybe the microwave if you use it alot, and of course if you have an electric stove.

Those types of motors usually run more efficiently on slightly higher voltage. Voltage up, current is the same or lower. Well power actually, it might be the same current but the phase changes the power factor. You pay by the watt, not the amp.


I think you are mistaken.

Some years ago I put a voltage stabilizer on a large fan. (adjustable
AC voltage regulator intended to be used for large motors) As I
adjusted the voltage lower the current dropped linearly until it
reached about 95 VAC then started rising exponentially as I dropped it
lower.

Torque of the motor may be dependent on voltage, but the torque
required for a refrigeration compressor varies with time. Starting up
with the system equilibrated, there\'s little back-pressure on the
compressor so it is lightly loaded, as back pressure builds the torque
necessary to maintain synchronous speed increases.
snip

But if you have a momentary power dropout, it has to restart into the
full back-pressure of the evaporator. If the A/C isn\'t a tiny one, I
sure wouldn\'t be mickey-mousing anything that would increase the mains
impedance.

Electrical codes contain a lot of non-obvious and very expensive wisdom.

Cheers

Phil Hobbs
You are correct - This controller has a built in time delay and won\'t
allow me to turn the compressor on and off at will. Commercial
(large) AC\'s monitor the back pressure before allowing the compressors
to run, and even cheap consumer products like refrigerators have an
\"overload relay\" that over heats (because the compressor motor is
stalled and eating a lot of amps) then the bi-metallic relay cools off
and eventually gives it another go.
 
D

default

Guest
On Tue, 14 Jul 2020 09:07:33 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-07-14 07:04, default wrote:
On Mon, 13 Jul 2020 16:49:33 -0700 (PDT), jurb6006@gmail.com wrote:

Your bill went up because of light bulbs and shit with heating elements, maybe the microwave if you use it alot, and of course if you have an electric stove.

Those types of motors usually run more efficiently on slightly higher voltage. Voltage up, current is the same or lower. Well power actually, it might be the same current but the phase changes the power factor. You pay by the watt, not the amp.


I think you are mistaken.

Some years ago I put a voltage stabilizer on a large fan. (adjustable
AC voltage regulator intended to be used for large motors) As I
adjusted the voltage lower the current dropped linearly until it
reached about 95 VAC then started rising exponentially as I dropped it
lower.

Torque of the motor may be dependent on voltage, but the torque
required for a refrigeration compressor varies with time. Starting up
with the system equilibrated, there\'s little back-pressure on the
compressor so it is lightly loaded, as back pressure builds the torque
necessary to maintain synchronous speed increases.
snip

But if you have a momentary power dropout, it has to restart into the
full back-pressure of the evaporator. If the A/C isn\'t a tiny one, I
sure wouldn\'t be mickey-mousing anything that would increase the mains
impedance.

Electrical codes contain a lot of non-obvious and very expensive wisdom.

Cheers

Phil Hobbs
You are correct - This controller has a built in time delay and won\'t
allow me to turn the compressor on and off at will. Commercial
(large) AC\'s monitor the back pressure before allowing the compressors
to run, and even cheap consumer products like refrigerators have an
\"overload relay\" that over heats (because the compressor motor is
stalled and eating a lot of amps) then the bi-metallic relay cools off
and eventually gives it another go.
 
D

default

Guest
On Tue, 14 Jul 2020 10:18:35 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-07-14 09:12, Bill Gill wrote:
On 7/14/2020 8:07 AM, Phil Hobbs wrote:
On 2020-07-14 07:04, default wrote:
On Mon, 13 Jul 2020 16:49:33 -0700 (PDT), jurb6006@gmail.com wrote:

Your bill went up because of light bulbs and shit with heating
elements, maybe the microwave if you use it alot, and of course if
you have an electric stove.

Those types of motors usually run more efficiently on slightly
higher voltage. Voltage up, current is the same or lower. Well power
actually, it might be the same current but the phase changes the
power factor. You pay by the watt, not the amp.


I think you are mistaken.

Some years ago I put a voltage stabilizer on a large fan.  (adjustable
AC voltage regulator intended to be used for large motors) As I
adjusted the voltage lower the current dropped linearly until it
reached about 95 VAC then started rising exponentially as I dropped it
lower.

Torque of the motor may be dependent on voltage, but the torque
required for a refrigeration compressor varies with time.  Starting up
with the system equilibrated, there\'s little back-pressure on the
compressor so it is lightly loaded, as back pressure builds the torque
necessary to maintain synchronous speed increases.
snip

But if you have a momentary power dropout, it has to restart into the
full back-pressure of the evaporator.  If the A/C isn\'t a tiny one, I
sure wouldn\'t be mickey-mousing anything that would increase the mains
impedance.

Electrical codes contain a lot of non-obvious and very expensive wisdom.

Cheers

Phil Hobbs




My central AC won\'t restart immediately after a dropout.  It has
a delay time to allow the pressure to drop.

Bill

That\'s certainly comforting, but isn\'t universal, at least in smaller
units. The thing I\'d be worried about is a short-that-isnt-a-short--as
in a shorted rectifier in an old-time transformer/rectifier/filter
supply. The current isn\'t enough to blow the mains breaker but is quite
sufficient to make the transformer catch fire.

I lost a very nice Krohn-Hite dual channel filter that way--a \'computer
grade\' capacitor\'s clamp had gotten loose over the years, and it slipped
down and shorted out to the box, resulting in clouds of transformer
smoke. It was a good thing that I was in the lab at the time. Didn\'t
even blow the fuse in the unit. (A bit of fish paper would have been a
nice touch.)

When nobody\'s around, we keep everything turned off at the power bar to
prevent that sort of thing--industrial-type Tripplites, natch.

Cheers

Phil Hobbs
I have a wall-switch that disconnects the mains from the AC outlet. I
don\'t trust leaving it on and unattended when I\'m away.

I am curious about how they do the time delay though.... If the AC
power has been off for a time (several minutes) and I apply power the
compressor will run right away. Yet if I switch the mains off and on
quickly it goes into it\'s time delay.

I figure that they must be looking at the charge on a cap that
gradually bleeds off when power is removed - and prevents a re-start
and goes into it\'s timing cycle instead. Easy to implement with a
micro controller chip...
 
D

default

Guest
On Tue, 14 Jul 2020 10:18:35 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2020-07-14 09:12, Bill Gill wrote:
On 7/14/2020 8:07 AM, Phil Hobbs wrote:
On 2020-07-14 07:04, default wrote:
On Mon, 13 Jul 2020 16:49:33 -0700 (PDT), jurb6006@gmail.com wrote:

Your bill went up because of light bulbs and shit with heating
elements, maybe the microwave if you use it alot, and of course if
you have an electric stove.

Those types of motors usually run more efficiently on slightly
higher voltage. Voltage up, current is the same or lower. Well power
actually, it might be the same current but the phase changes the
power factor. You pay by the watt, not the amp.


I think you are mistaken.

Some years ago I put a voltage stabilizer on a large fan.  (adjustable
AC voltage regulator intended to be used for large motors) As I
adjusted the voltage lower the current dropped linearly until it
reached about 95 VAC then started rising exponentially as I dropped it
lower.

Torque of the motor may be dependent on voltage, but the torque
required for a refrigeration compressor varies with time.  Starting up
with the system equilibrated, there\'s little back-pressure on the
compressor so it is lightly loaded, as back pressure builds the torque
necessary to maintain synchronous speed increases.
snip

But if you have a momentary power dropout, it has to restart into the
full back-pressure of the evaporator.  If the A/C isn\'t a tiny one, I
sure wouldn\'t be mickey-mousing anything that would increase the mains
impedance.

Electrical codes contain a lot of non-obvious and very expensive wisdom.

Cheers

Phil Hobbs




My central AC won\'t restart immediately after a dropout.  It has
a delay time to allow the pressure to drop.

Bill

That\'s certainly comforting, but isn\'t universal, at least in smaller
units. The thing I\'d be worried about is a short-that-isnt-a-short--as
in a shorted rectifier in an old-time transformer/rectifier/filter
supply. The current isn\'t enough to blow the mains breaker but is quite
sufficient to make the transformer catch fire.

I lost a very nice Krohn-Hite dual channel filter that way--a \'computer
grade\' capacitor\'s clamp had gotten loose over the years, and it slipped
down and shorted out to the box, resulting in clouds of transformer
smoke. It was a good thing that I was in the lab at the time. Didn\'t
even blow the fuse in the unit. (A bit of fish paper would have been a
nice touch.)

When nobody\'s around, we keep everything turned off at the power bar to
prevent that sort of thing--industrial-type Tripplites, natch.

Cheers

Phil Hobbs
I have a wall-switch that disconnects the mains from the AC outlet. I
don\'t trust leaving it on and unattended when I\'m away.

I am curious about how they do the time delay though.... If the AC
power has been off for a time (several minutes) and I apply power the
compressor will run right away. Yet if I switch the mains off and on
quickly it goes into it\'s time delay.

I figure that they must be looking at the charge on a cap that
gradually bleeds off when power is removed - and prevents a re-start
and goes into it\'s timing cycle instead. Easy to implement with a
micro controller chip...
 
S

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Guest
On Mon, 13 Jul 2020 23:12:03 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

On Monday, July 13, 2020 at 8:31:34 AM UTC-7, default wrote:
I have an older window air conditioner that I\'d like to hang on to for
a few more years. The name plate says it is 220 VAC and since the
power company went through and upgraded the distribution network and
replaced HT and transformers my service which had been running 210-220
volts is now a steady 250 volts and my bill is up ~15%.
...

I was wondering if putting in 240 VAC to 24VAC center tapped, 10 amp
power transformer, wired to buck the voltage makes any sense?

It doesn\'t make much sense to me; ask, instead, the power company to
adjust the line voltage to an acceptable value. The taps in their
transmission line drops are the solution to many such problems, if
they know that you have found an excessive voltage. I\'m not sure
250V average is excessive, but if there are peaks and dips...
I called my power company to complain about the high voltage and they
said it was within spec. The voltage at my place is 250 minimum with
occasional spikes to 260. The spikes are transient but long enough in
duration to be read with a digital voltmeter. And long enough for the
CNC lathe\'s spindle drive to alarm out.
Eric
 
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