On Monday, August 29, 2016 at 6:46:21 PM UTC-4, Tony944 wrote:



Again yes MOV are used in power supplies,

Not just on power supplies, they are used on circuit boards to protect
electronics that has nothing to do with a power supply. Like on a
phone jack for a modem for example.


but MOV came out about 30 years
ago
what was used before that time?

What does it matter? The purpose of the caps on the incoming
power to electronics boards use the caps we are talking about
not for surge protection, but to SUPPLY DC current to the components
on the board due to sudden changes in current needed, eg digital
circuits that are switching. These boards have both the caps for
that purpose and they may have MOVs to protect from external
surges. Two different purposes. The cap is like a local battery,
when a circuit on the board suddenly switches, it creates a need
for additional current. If that current has to come through feet
of wire, it has impedance blocking it. And as the current flows
it would possibly have effects on other boards connected to the
power supply wires. By having the cap there, it momentarily
serves as as source for the extra current, so there is no dip
in the voltage.



There some Capacitors that are made for very
high-power in switching circuits like power station that can very easily
kill person
but I do not think that we are talking about those.

So why bring it up?


Electrolytic common definition in DC systems not necessarily in the AC
systems
and no commonly they do not get charge in AC systems as I said
they are use
limit current but 90 deg. out of phase to the AC line to start or run
motors, what
would be classification of running Capacitor which is on at all the time
when power
source is applied.

It's doing the same thing as the hard start cap, it's providing
phase shift. In the case of the PSC motor, it needs that phase
shift all the time, not just when starting.



You can also change power consumption by change the value
of capacitor. (Don't do it unless you know what you are doing)
Go back to DC: the DC voltage most not be able to pass through any capacitor
unless it is bad and is leaking through, but the CA will' because that is
what is should do.

Voltage doesn't pass through anything, current can. And yes AC
current will flow through a cap, never said otherwise.


Some of you guys can say whatever you want I am not here to squabble over
some stupidity.
So gents have nice day...

If you have a point here, IDK what it is.

On Monday, August 29, 2016 at 5:46:21 PM UTC-5, Tony944 wrote:
"Ralph Mowery" wrote in message
k.net...

In article ,
says...


The hard start cap is only good for momentary contact. It's to be
disconnected as soon as the motor has achieved 'run' rpms. Otherwise,
you'd toast the cap. IE; it sends a surge of current to the start
windings to get the motor up and going, and within a few seconds, a
relay is supposed (in some) to kick it off the start cap/windings and
onto the run cap/run windings.

As I said though, hvac isn't my specialty and I fully admit I could
be wrong in how the cap is being used in this way.


Everyone seems to be dancing around the hard start capacitor.

It allows the motor to draw lots more current for a very short time to
get the motor up to speed faster. As the motor spins up it draws less
and less current. When it is at its rated speed , it will draw less
current .
As most fuses and breakers do not trip at the instant they reach their
marked current, but take some time to heat up and trip depending on how
much over the marked value the current is. By using the hard start kit
the current will be over the marked value by a good ammount, but it will
be short enough not to trip the breaker. Where without the kit it will
take the motor longer to get up to speed and the breaker will trip
during the longer slightly over loaded condition.

Think of it as how long you can hold your hand to a hot surface. You
can touch a very hot object for a very short time and not get burnt.
YOu can touch a cooler object longer before a burn.
--
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Again yes MOV are used in power supplies, but MOV came out about 30 years
ago
what was used before that time? There some Capacitors that are made for very
high-power in switching circuits like power station that can very easily
kill person
but I do not think that we are talking about those.
Electrolytic common definition in DC systems not necessarily in the AC
systems
and no commonly they do not get charge in AC systems as I said, they are use
limit current but 90 deg. out of phase to the AC line to start or run
motors, what
would be classification of running Capacitor which is on at all the time
when power
source is applied. You can also change power consumption by change the value
of capacitor. (Don't do it unless you know what you are doing)
Go back to DC: the DC voltage most not be able to pass through any capacitor
unless it is bad and is leaking through, but the CA will' because that is
what is should do.
Some of you guys can say whatever you want I am not here to squabble over
some stupidity.
So gents have nice day...


I've repaired industrial control discrete component loaded circuit boards from the early 1960's that had MOV's mounted on them. Those particular axial lead components were the size and shape of AA batteries. It was only circuit boards from some years later that I saw disk shaped MOV's. The MOV has been around longer than you may think. Some of them are huge. Look at the symbol for it used in electronic diagrams which closely resembles the early component shape but I feel it may be more a representation of it being a voltage dependent "resistor". ^_^

[8~{} Uncle Bored Monster

trader_4
Mon, 29
Aug 2016 22:20:06 GMT in alt.home.repair, wrote:

Yes, I know that. The point is the start cap is not holding a
charge to send to the motor. As I showed you, all the cap would
have in the way of charge is whatever it accumulates in under
1/120 of a second and that's insignificant.

I'm not talking about a run cap...

The start cap already has a charge, depending on the wiring to the
relay. It's waiting to be connected to the motor for startup assistance
and when it's disconnected, thanks to the relay wiring, it'll be
recharged for the next run.

There is no charge to make a surge. It works by creating a phase
shift, which is necessary to get the motor rotating. Where is
this alleged surge coming from? The start cap has no power to it

Oh, but there is.. The start capacitor is energized and patiently waits
to be tied into the compressor motor, usually on the start windings.

This is why hvac techs always drain capacitors when they encounter
them. Only an idiot would assume a capacitor isn't storing a charge and
proceed to screw around with things connected to it. Especially if the
device it's connected to has been powered up (or tried to power up)
recently.

You'll notice (if you watched the video from the first url I posted)
that the start caps usually have bleeding resistors attached to them;
that's because they do store current and you wouldn't want to expose
yourself to it while servicing the machine.

https://highperformancehvac.com/star...c-compressors/

Start Capacitors for HVAC Compressors - Potential Relay

The next method to help the compressor on start up is to add a start
capacitor. This is added to the HVAC compressor circuit along with a
potential relay. The potential relay is necessary. Necessary because we
do not want to leave the start capacitor in the compressor circuit
after the compressor starts. The potential relay allows the start
capacitor to assist the compressor to start. It then opens the circuit
between the compressor and the start capacitor after the compressor
starts and is running.

The potential relay does this using back EMF or back electromotive
force. Otherwise known as back voltage coming from the compressor. As
the compressor starts and voltage goes through the system it sends out
a back EMF voltage. This voltage energizes the coil in the potential
relay for the start capacitor.
Start Capacitors for HVAC Compressors | Back EMF

The back EMF is constant while the compressor is running. The relay
will hold the start capacitor out of the compressor circuit because of
the Back EMF. Until the compressor stops. Then the coil in the relay is
de-energized and start capacitor awaits another start up. The start
capacitor can assist the compressor on the next start up.

Other methods of taking the start capacitor out of the circuit include
a current relay. The current relay opens the circuit between the
compressor windings and the start capacitor. The current relay
works off a certain amount of current.

I (like the previous website) was summerizing the entire process and
saying it 'boosts' (by boosts, it gives the motor a shove of sorts, if
you will to get the rotor spinning) the motor for startup; which it
does. You're the one who wanted to get all technical about how it does
this. Which is fine, I'm usually anal about details myself.

You are.

Depending on your pov, I suppose. I said it boosts it (it does) but
neglected to provide the gory details upon how it's doing this.

Sometimes even folks that should know better get it wrong. They're
a supplier, but they have it wrong. There is no "surge", it's a
phase shift. They only understand the static concept of a cap,
ie how it stores charge.

You might want to review the videos also included at the link. The
first url I shared isn't from a distributor, but a manufacturer of
start/run caps. I'd think they have some idea of what their own
products do and how they do it.

The above is also consistent with the fact that many motors have
a run capacitor. If caps work in motors by doing a "surge",
then what is one doing in some motors all the time? The answer
is those motors need that phase shift to run.

A run cap isn't the same as a start cap. You can't interchange them and
expect the device to run reliably. It won't. You could use a run cap as
a start cap, but you can't use the start cap as a run cap; it can't
handle being connected for more than a few seconds. And, if you decided
to use a run cap as a start cap, you'd probably need quite a few to
makeup the difference in capacitance.

The start cap has a different capacitance and is only intended to give
the motor a boost (boost is easier to use than explaining EMF, etc to a
lay person) to get it rolling. At that point, it's pulled from the
motor and the run capacitor takes over. If you left the start capacitor
tied into the circuit for more than a few seconds, you'll kill it. It
could just vent, leak, and/or release it's internal core from the outer
casing (semi violently) OTH, A run capacitor can be tied into the power
all day long and you won't hurt it. It will hold a charge though, so,
don't be touching it with your fingers when you shut it down. You'll
want to use a resistor and bleed it off. Also, make sure you set your
meter to test for DC current to verify the cap is dead. Why DC? If you
turn the cap off during the period of AC wave form other than zero
crossing, the cap will store DC voltage upto dangerous/lethal levels.

On AC motors, they rely on EMF and 'phase shifting'. OTH, on a DC Motor
(I know this because I was once banned for cheating on an rc race
track) they will give it a boost in the more, legit sense. As in,
dumping everything they got at once into your motor, giving it more
torque, more rpms, faster car. [g]

I tied a bank of small caps into my car, and when I pressed 'turbo' it
dumped the banks entire charge directly into the motor. As soon as I
let off the turbo button and/or the caps drained down, they'd
automatically kick a small (tiny) relay over to put the motor back on
the battery pack and also reconnect them to the battery pack to
recharge, quickly. It would take a few seconds and then, I could hit
turbo again. [g]

The result? Assuming the drive train held up and I didn't lose
traction, off and away it would go, leaving the other cars in it's
dust.

I realize the cap is functioning in a slightly different manner when
using AC, but the end result is the same; the motor gets a loving push
(help to start) without it having to pull a massive ****load of amps to
free it's rotor. You know, the infamous 'rotor locked' on startup
position.

I'll try to be much more specific with you in the future, ok? Instead
of just stating that it gives the motor a push or boost, I should have
been more specific on how it's doing this. My apologies for not having
done so previously.


--
MID:
Hmmm. I most certainly don't understand how I can access a copy of a
zip file but then not be able to unzip it so I can watch it. That
seems VERY clever!
http://al.howardknight.net/msgid.cgi?ID=145716711400

On Monday, August 29, 2016 at 11:20:08 PM UTC-4, Uncle Monster wrote:
On Monday, August 29, 2016 at 5:46:21 PM UTC-5, Tony944 wrote:
"Ralph Mowery" wrote in message
k.net...

In article ,
says...


The hard start cap is only good for momentary contact. It's to be
disconnected as soon as the motor has achieved 'run' rpms. Otherwise,
you'd toast the cap. IE; it sends a surge of current to the start
windings to get the motor up and going, and within a few seconds, a
relay is supposed (in some) to kick it off the start cap/windings and
onto the run cap/run windings.

As I said though, hvac isn't my specialty and I fully admit I could
be wrong in how the cap is being used in this way.


Everyone seems to be dancing around the hard start capacitor.

It allows the motor to draw lots more current for a very short time to
get the motor up to speed faster. As the motor spins up it draws less
and less current. When it is at its rated speed , it will draw less
current .
As most fuses and breakers do not trip at the instant they reach their
marked current, but take some time to heat up and trip depending on how
much over the marked value the current is. By using the hard start kit
the current will be over the marked value by a good ammount, but it will
be short enough not to trip the breaker. Where without the kit it will
take the motor longer to get up to speed and the breaker will trip
during the longer slightly over loaded condition.

Think of it as how long you can hold your hand to a hot surface. You
can touch a very hot object for a very short time and not get burnt.
YOu can touch a cooler object longer before a burn.
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

Again yes MOV are used in power supplies, but MOV came out about 30 years
ago
what was used before that time? There some Capacitors that are made for very
high-power in switching circuits like power station that can very easily
kill person
but I do not think that we are talking about those.
Electrolytic common definition in DC systems not necessarily in the AC
systems
and no commonly they do not get charge in AC systems as I said, they are use
limit current but 90 deg. out of phase to the AC line to start or run
motors, what
would be classification of running Capacitor which is on at all the time
when power
source is applied. You can also change power consumption by change the value
of capacitor. (Don't do it unless you know what you are doing)
Go back to DC: the DC voltage most not be able to pass through any capacitor
unless it is bad and is leaking through, but the CA will' because that is
what is should do.
Some of you guys can say whatever you want I am not here to squabble over
some stupidity.
So gents have nice day...


I've repaired industrial control discrete component loaded circuit boards from the early 1960's that had MOV's mounted on them. Those particular axial lead components were the size and shape of AA batteries. It was only circuit boards from some years later that I saw disk shaped MOV's. The MOV has been around longer than you may think. Some of them are huge. Look at the symbol for it used in electronic diagrams which closely resembles the early component shape but I feel it may be more a representation of it being a voltage dependent "resistor". ^_^

[8~{} Uncle Bored Monster

I was going to comment that MOVs were around longer than 30 years too,
but figured it was a nit, as MOVs aren't the issue at hand. I know they
were around at least in the 70s and there were varistors of other types
before that. Also, they weren't nearly as important prior to that time,
because most appliances didn't have sensitive semiconductors in them
that were particularly prone to surge damage.

In article ,
says...


There is no charge to make a surge. It works by creating a phase
shift, which is necessary to get the motor rotating. Where is
this alleged surge coming from? The start cap has no power to it

Oh, but there is.. The start capacitor is energized and patiently waits
to be tied into the compressor motor, usually on the start windings.

This is why hvac techs always drain capacitors when they encounter
them. Only an idiot would assume a capacitor isn't storing a charge and
proceed to screw around with things connected to it. Especially if the
device it's connected to has been powered up (or tried to power up)
recently.


The capacitors are not sitting there with a charge on them waiting to
dump it to start the motor. The only reason they may or may not be
charged is that the alternating current goes from 0 to the peak voltage
during the cycle. Depending on where in the cycle the relay or other
set of contacts open the voltage left on the capacitor could be anywhere
from the peak negative to the peak positive voltage.

The purpose is to provide a phase shift, not hold any charge to provide
a bost.

Just trying to asume that what you say is correct, explain how if the
charge on the capacitor is the wrong polarity (as they can only store
DC) that the voltage would buck the alternating current and the motor
would not start correctly.

---
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On Tuesday, August 30, 2016 at 5:23:58 AM UTC-4, Diesel wrote:
trader_4
Mon, 29
Aug 2016 22:20:06 GMT in alt.home.repair, wrote:

Yes, I know that. The point is the start cap is not holding a
charge to send to the motor. As I showed you, all the cap would
have in the way of charge is whatever it accumulates in under
1/120 of a second and that's insignificant.

I'm not talking about a run cap...


Neither am I. The above is specific to either a run cap or a start
cap. Neither has any charge on it prior to throwing the switch to
apply power to the motor. The point is there is no energy there
prior to that, no reservoir, to
aid in starting the motor. You compared it to a cap at an amplifier
in a car. That is very different, because there it's a DC circuit
and the cap is fully charged and available to supply instantaneous
current needs instead of it all having to come from the battery
which is located many feet away, through the impedance of that wire.



The start cap already has a charge, depending on the wiring to the
relay. It's waiting to be connected to the motor for startup assistance
and when it's disconnected, thanks to the relay wiring, it'll be
recharged for the next run.


That's just flat out wrong. The start cap is on the load side of
the contactor in the AC equipment. It's not energized when the
eqpt is off. There is no charge in it to provide some kind of
energy boost to the motor. Again, the cap works by providing
PHASE SHIFT. You compared it to a cap on an amp in a car. It's
not like that at all. The cap in the car amp is acting as a
charge reservoir because it's a DC circuit. The cap is fully
charged and like a small battery. If the amp has a sudden need
for more current, it can supply it without the impedance of the
wires going back to the battery.

The AC compressor is an AC motor and it uses the phase shift
that a cap provides to help create the proper rotating magnetic
field. The two uses are very different. That is all that I'm
saying.


There is no charge to make a surge. It works by creating a phase
shift, which is necessary to get the motor rotating. Where is
this alleged surge coming from? The start cap has no power to it

Oh, but there is.. The start capacitor is energized and patiently waits
to be tied into the compressor motor, usually on the start windings.


Wrong again. There is no charging, then waiting. Before the contactor
closes, the start capacitor and motor have no power applied. As soon
as the contactor closes, the motor and the start capacitor have power
applied, they are part of the same circuit.


This is why hvac techs always drain capacitors when they encounter
them. Only an idiot would assume a capacitor isn't storing a charge and
proceed to screw around with things connected to it. Especially if the
device it's connected to has been powered up (or tried to power up)
recently.


Assuming the charge isn't drained off by the motor, the cap could
have anywhere from no charge, to some charge in one polarity, to
some charge in the opposite polarity. It all depends on where in
the 1/60 sec AC cycle it was disconnected. Whatever small spark
you get is irrelevant, because that isn't what makes the motor
start. It's the PHASE SHIFT.



You'll notice (if you watched the video from the first url I posted)
that the start caps usually have bleeding resistors attached to them;
that's because they do store current and you wouldn't want to expose
yourself to it while servicing the machine.


If it has bleeding resistors, where is the alleged charge store that
comes into play on starting coming from?



https://highperformancehvac.com/star...c-compressors/

Start Capacitors for HVAC Compressors - Potential Relay

The next method to help the compressor on start up is to add a start
capacitor. This is added to the HVAC compressor circuit along with a
potential relay. The potential relay is necessary. Necessary because we
do not want to leave the start capacitor in the compressor circuit
after the compressor starts. The potential relay allows the start
capacitor to assist the compressor to start. It then opens the circuit
between the compressor and the start capacitor after the compressor
starts and is running.

The potential relay does this using back EMF or back electromotive
force. Otherwise known as back voltage coming from the compressor. As
the compressor starts and voltage goes through the system it sends out
a back EMF voltage. This voltage energizes the coil in the potential
relay for the start capacitor.
Start Capacitors for HVAC Compressors | Back EMF

The back EMF is constant while the compressor is running. The relay
will hold the start capacitor out of the compressor circuit because of
the Back EMF. Until the compressor stops. Then the coil in the relay is
de-energized and start capacitor awaits another start up. The start
capacitor can assist the compressor on the next start up.

Other methods of taking the start capacitor out of the circuit include
a current relay. The current relay opens the circuit between the
compressor windings and the start capacitor. The current relay
works off a certain amount of current.

I (like the previous website) was summerizing the entire process and
saying it 'boosts' (by boosts, it gives the motor a shove of sorts, if
you will to get the rotor spinning) the motor for startup; which it
does. You're the one who wanted to get all technical about how it does
this. Which is fine, I'm usually anal about details myself.


I only got "all techinical" when what you described, comparing it
to that DC car amp, was totally wrong. The cap isn't supplying
extra current into the motor, it's shifting the phase of the rotating
magnetic field.




You are.

Depending on your pov, I suppose. I said it boosts it (it does) but
neglected to provide the gory details upon how it's doing this.


You specifically compared it to a cap in a car amplifier, which is
a DC circuit. The function of the cap there is completely different
than how it works in an AC motor.



Sometimes even folks that should know better get it wrong. They're
a supplier, but they have it wrong. There is no "surge", it's a
phase shift. They only understand the static concept of a cap,
ie how it stores charge.

You might want to review the videos also included at the link.

You might want to review what phase shift is. These videos are targeted
at someone who wants to buy a start cap and put it in. They don't
describe the physics involved, they just use vague terms like the
cap assists the motor in starting.


The
first url I shared isn't from a distributor, but a manufacturer of
start/run caps. I'd think they have some idea of what their own
products do and how they do it.

The above is also consistent with the fact that many motors have
a run capacitor. If caps work in motors by doing a "surge",
then what is one doing in some motors all the time? The answer
is those motors need that phase shift to run.

A run cap isn't the same as a start cap. You can't interchange them and
expect the device to run reliably. It won't.

Who ever said it would? All I said was they are both caps, they both
work by providing phase shift. That they work by providing phase
shift explains how they can both be there. If the cap just serves
as a charge reservoir, like it does in the car amp, then what is the
run cap doing there all the time? Your surge, charge assist explanation
would make no sense. The phase shift and correct explanation does
explain it.



You could use a run cap as
a start cap, but you can't use the start cap as a run cap; it can't
handle being connected for more than a few seconds. And, if you decided
to use a run cap as a start cap, you'd probably need quite a few to
makeup the difference in capacitance.

The start cap has a different capacitance and is only intended to give
the motor a boost (boost is easier to use than explaining EMF, etc to a
lay person) to get it rolling.

It's actually giving it a phase shift to provide the correct rotating
field. It's not really what I'd call a "boost".


At that point, it's pulled from the
motor and the run capacitor takes over.

And what is that run cap doing? If the purpose of caps in these
motors is to give a "boost" from some mysterious stored charge,
then what is that run cap doing? Answer: both the run and start
cap work by providing phase shift. In a cap, current and voltage
are out of phase by 90 degrees.


If you left the start capacitor
tied into the circuit for more than a few seconds, you'll kill it. It
could just vent, leak, and/or release it's internal core from the outer
casing (semi violently) OTH, A run capacitor can be tied into the power
all day long and you won't hurt it. It will hold a charge though, so,
don't be touching it with your fingers when you shut it down. You'll
want to use a resistor and bleed it off. Also, make sure you set your
meter to test for DC current to verify the cap is dead. Why DC? If you
turn the cap off during the period of AC wave form other than zero
crossing, the cap will store DC voltage upto dangerous/lethal levels.

On AC motors, they rely on EMF and 'phase shifting'. OTH, on a DC Motor
(I know this because I was once banned for cheating on an rc race
track) they will give it a boost in the more, legit sense. As in,
dumping everything they got at once into your motor, giving it more
torque, more rpms, faster car. [g]

I tied a bank of small caps into my car, and when I pressed 'turbo' it
dumped the banks entire charge directly into the motor. As soon as I
let off the turbo button and/or the caps drained down, they'd
automatically kick a small (tiny) relay over to put the motor back on
the battery pack and also reconnect them to the battery pack to
recharge, quickly. It would take a few seconds and then, I could hit
turbo again. [g]

The result? Assuming the drive train held up and I didn't lose
traction, off and away it would go, leaving the other cars in it's
dust.

I realize the cap is functioning in a slightly different manner when
using AC,

I don;t think you do, because it's in a totally different manner.


but the end result is the same; the motor gets a loving push
(help to start) without it having to pull a massive ****load of amps to
free it's rotor. You know, the infamous 'rotor locked' on startup
position.


Which it does by phase shift and which occurs with the cap first
seeing current when the switch or contactor is closed, not having
some pre-stored boost charge.


I'll try to be much more specific with you in the future, ok? Instead
of just stating that it gives the motor a push or boost, I should have
been more specific on how it's doing this. My apologies for not having
done so previously.


Like I said, and keep saying, my only point was that the cap doesn't
work like a charge reservoir, using stored charge to give a kick
to the compressor. It doesn't work like the cap in the DC car
example you used. You're not the only one here who has it wrong.
Maybe you don't care, don't want to learn, but I think some people
want to know how it really works. The incorrect version leads to
other misconceptions, like Ralph thinking that having the HS cap
means that it pulls more surge current initially to get the motor
going. It doesn't, it pulls less. And that is again explained by
the fact that what it really does is provide phase shift to get
the right rotating magnetic field that gets the motor started
easier, faster, and with less current.

Diesel explained :
trader_4
Mon, 29
Aug 2016 22:20:06 GMT in alt.home.repair, wrote:

Yes, I know that. The point is the start cap is not holding a
charge to send to the motor. As I showed you, all the cap would
have in the way of charge is whatever it accumulates in under
1/120 of a second and that's insignificant.

I'm not talking about a run cap...

The start cap already has a charge, depending on the wiring to the
relay. It's waiting to be connected to the motor for startup assistance
and when it's disconnected, thanks to the relay wiring, it'll be
recharged for the next run.

There is no charge to make a surge. It works by creating a phase
shift, which is necessary to get the motor rotating. Where is
this alleged surge coming from? The start cap has no power to it

Oh, but there is.. The start capacitor is energized and patiently waits
to be tied into the compressor motor, usually on the start windings.

This is why hvac techs always drain capacitors when they encounter
them. Only an idiot would assume a capacitor isn't storing a charge and
proceed to screw around with things connected to it. Especially if the
device it's connected to has been powered up (or tried to power up)
recently.

You'll notice (if you watched the video from the first url I posted)
that the start caps usually have bleeding resistors attached to them;
that's because they do store current and you wouldn't want to expose
yourself to it while servicing the machine.

https://highperformancehvac.com/star...c-compressors/

Start Capacitors for HVAC Compressors - Potential Relay

The next method to help the compressor on start up is to add a start
capacitor. This is added to the HVAC compressor circuit along with a
potential relay. The potential relay is necessary. Necessary because we
do not want to leave the start capacitor in the compressor circuit
after the compressor starts. The potential relay allows the start
capacitor to assist the compressor to start. It then opens the circuit
between the compressor and the start capacitor after the compressor
starts and is running.

The potential relay does this using back EMF or back electromotive
force. Otherwise known as back voltage coming from the compressor. As
the compressor starts and voltage goes through the system it sends out
a back EMF voltage. This voltage energizes the coil in the potential
relay for the start capacitor.
Start Capacitors for HVAC Compressors | Back EMF

The back EMF is constant while the compressor is running. The relay
will hold the start capacitor out of the compressor circuit because of
the Back EMF. Until the compressor stops. Then the coil in the relay is
de-energized and start capacitor awaits another start up. The start
capacitor can assist the compressor on the next start up.

Other methods of taking the start capacitor out of the circuit include
a current relay. The current relay opens the circuit between the
compressor windings and the start capacitor. The current relay
works off a certain amount of current.

I (like the previous website) was summerizing the entire process and
saying it 'boosts' (by boosts, it gives the motor a shove of sorts, if
you will to get the rotor spinning) the motor for startup; which it
does. You're the one who wanted to get all technical about how it does
this. Which is fine, I'm usually anal about details myself.

You are.

Depending on your pov, I suppose. I said it boosts it (it does) but
neglected to provide the gory details upon how it's doing this.

Sometimes even folks that should know better get it wrong. They're
a supplier, but they have it wrong. There is no "surge", it's a
phase shift. They only understand the static concept of a cap,
ie how it stores charge.

You might want to review the videos also included at the link. The
first url I shared isn't from a distributor, but a manufacturer of
start/run caps. I'd think they have some idea of what their own
products do and how they do it.

The above is also consistent with the fact that many motors have
a run capacitor. If caps work in motors by doing a "surge",
then what is one doing in some motors all the time? The answer
is those motors need that phase shift to run.

A run cap isn't the same as a start cap. You can't interchange them and
expect the device to run reliably. It won't. You could use a run cap as
a start cap, but you can't use the start cap as a run cap; it can't
handle being connected for more than a few seconds. And, if you decided
to use a run cap as a start cap, you'd probably need quite a few to
makeup the difference in capacitance.

The start cap has a different capacitance and is only intended to give
the motor a boost (boost is easier to use than explaining EMF, etc to a
lay person) to get it rolling. At that point, it's pulled from the
motor and the run capacitor takes over. If you left the start capacitor
tied into the circuit for more than a few seconds, you'll kill it. It
could just vent, leak, and/or release it's internal core from the outer
casing (semi violently) OTH, A run capacitor can be tied into the power
all day long and you won't hurt it. It will hold a charge though, so,
don't be touching it with your fingers when you shut it down. You'll
want to use a resistor and bleed it off. Also, make sure you set your
meter to test for DC current to verify the cap is dead. Why DC? If you
turn the cap off during the period of AC wave form other than zero
crossing, the cap will store DC voltage upto dangerous/lethal levels.

On AC motors, they rely on EMF and 'phase shifting'. OTH, on a DC Motor
(I know this because I was once banned for cheating on an rc race
track) they will give it a boost in the more, legit sense. As in,
dumping everything they got at once into your motor, giving it more
torque, more rpms, faster car. [g]

I tied a bank of small caps into my car, and when I pressed 'turbo' it
dumped the banks entire charge directly into the motor. As soon as I
let off the turbo button and/or the caps drained down, they'd
automatically kick a small (tiny) relay over to put the motor back on
the battery pack and also reconnect them to the battery pack to
recharge, quickly. It would take a few seconds and then, I could hit
turbo again. [g]

The result? Assuming the drive train held up and I didn't lose
traction, off and away it would go, leaving the other cars in it's
dust.

I realize the cap is functioning in a slightly different manner when
using AC, but the end result is the same; the motor gets a loving push
(help to start) without it having to pull a massive ****load of amps to
free it's rotor. You know, the infamous 'rotor locked' on startup
position.

I'll try to be much more specific with you in the future, ok? Instead
of just stating that it gives the motor a push or boost, I should have
been more specific on how it's doing this. My apologies for not having
done so previously.

Without seeing the circuit diagram of the motor in question, I can only
assume that said motor has a 'start winding' which tells the
non-rotating motor which might have stopped in a position lined up with
a pole (or exactly between poles) to move off (in a certain direction)
the pole it is currently lined up with (or between) so that it "knows"
which direction it is meant to rotate in.

The *uncharged* capacitor presents an instantaneous short which
effectively connects the power to that 'start winding'. Once rotating,
the regular rotating poles take over and the start capacitor is
switched out by a centrifugal switch or other mechanism/device and if
needed there is a 'run capacitor' still in the circuit which provides
whatever shift is needed if any.

There are too many variations of motor types for me to know exactly
what kind is used in modern air conditioners, but a little reading
indicates that both start and run caps are often housed together in a
single unit to save space. Each "side" of such a capacitor would have a
different value indicated on the can.

A 'bleeding' resistor is American for what the Brits call a 'bloody'
resistor. I think what you meant was a 'bleeder' resistor which a
lot of equipment uses to bleed off any residual charge left in a
capacitor when the equipment is turned off.

On Tuesday, August 30, 2016 at 8:34:07 AM UTC-5, trader_4 wrote:
On Monday, August 29, 2016 at 11:20:08 PM UTC-4, Uncle Monster wrote:
On Monday, August 29, 2016 at 5:46:21 PM UTC-5, Tony944 wrote:
"Ralph Mowery" wrote in message
k.net...

In article ,
says...

The hard start cap is only good for momentary contact. It's to be
disconnected as soon as the motor has achieved 'run' rpms. Otherwise,
you'd toast the cap. IE; it sends a surge of current to the start
windings to get the motor up and going, and within a few seconds, a
relay is supposed (in some) to kick it off the start cap/windings and
onto the run cap/run windings.

As I said though, hvac isn't my specialty and I fully admit I could
be wrong in how the cap is being used in this way.

Everyone seems to be dancing around the hard start capacitor.

It allows the motor to draw lots more current for a very short time to
get the motor up to speed faster. As the motor spins up it draws less
and less current. When it is at its rated speed , it will draw less
current .
As most fuses and breakers do not trip at the instant they reach their
marked current, but take some time to heat up and trip depending on how
much over the marked value the current is. By using the hard start kit
the current will be over the marked value by a good ammount, but it will
be short enough not to trip the breaker. Where without the kit it will
take the motor longer to get up to speed and the breaker will trip
during the longer slightly over loaded condition.

Think of it as how long you can hold your hand to a hot surface. You
can touch a very hot object for a very short time and not get burnt.
YOu can touch a cooler object longer before a burn.
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

Again yes MOV are used in power supplies, but MOV came out about 30 years
ago
what was used before that time? There some Capacitors that are made for very
high-power in switching circuits like power station that can very easily
kill person
but I do not think that we are talking about those.
Electrolytic common definition in DC systems not necessarily in the AC
systems
and no commonly they do not get charge in AC systems as I said, they are use
limit current but 90 deg. out of phase to the AC line to start or run
motors, what
would be classification of running Capacitor which is on at all the time
when power
source is applied. You can also change power consumption by change the value
of capacitor. (Don't do it unless you know what you are doing)
Go back to DC: the DC voltage most not be able to pass through any capacitor
unless it is bad and is leaking through, but the CA will' because that is
what is should do.
Some of you guys can say whatever you want I am not here to squabble over
some stupidity.
So gents have nice day...

I've repaired industrial control discrete component loaded circuit boards from the early 1960's that had MOV's mounted on them. Those particular axial lead components were the size and shape of AA batteries. It was only circuit boards from some years later that I saw disk shaped MOV's. The MOV has been around longer than you may think. Some of them are huge. Look at the symbol for it used in electronic diagrams which closely resembles the early component shape but I feel it may be more a representation of it being a voltage dependent "resistor". ^_^

[8~{} Uncle Bored Monster

I was going to comment that MOVs were around longer than 30 years too,
but figured it was a nit, as MOVs aren't the issue at hand. I know they
were around at least in the 70s and there were varistors of other types
before that. Also, they weren't nearly as important prior to that time,
because most appliances didn't have sensitive semiconductors in them
that were particularly prone to surge damage.


I want an MOV the size of the one in the picture to protect my computer power supply. ^_^

https://en.wikipedia.org/wiki/Varist...e:Varistor.jpg

[8~{} Uncle Huge Monster

trader_4
Tue, 30
Aug 2016 15:08:14 GMT in alt.home.repair, wrote:

Neither am I. The above is specific to either a run cap or a
start cap. Neither has any charge on it prior to throwing the
switch to apply power to the motor. The point is there is no
energy there prior to that, no reservoir, to
aid in starting the motor. You compared it to a cap at an
amplifier in a car. That is very different, because there it's a
DC circuit and the cap is fully charged and available to supply
instantaneous current needs instead of it all having to come from
the battery which is located many feet away, through the impedance
of that wire.

I agree, bad comparison on my part. When using AC it's phase
shifting. When using DC, it's holding and dumping it's charge. For
simplicty sake, I just say it boosts them and don't go further into
the specific details. One (DC) actually does boost and the other
assists it with a phase shift (so not technically a boost, but, it
does cause less of a startup drain on the panel and the motor comes
up to speed quickly)

I also clearly messed up the explanation when I said the start cap
holds a charge (I was confusing it for the DC type which is what I
have more hands one experience with) and dumps it into the AC motor.
My apologies. That's what I get for playing on usenet on little
sleep. [g]

The AC compressor is an AC motor and it uses the phase shift
that a cap provides to help create the proper rotating magnetic
field. The two uses are very different. That is all that I'm
saying.

Understood.

You specifically compared it to a cap in a car amplifier, which is
a DC circuit. The function of the cap there is completely
different than how it works in an AC motor.

I agree. it was a **** poor comparison on my part. And I should have
been much more specific. I should also have started that when used in
the AC start method, it's phase shifting; so, you're right, not
technically a 'boost', but essentially in laymens terms, it is. The
motor comes up to speed quickly and doesn't draw down an excessive
amount of amps to do it, with the start caps help.

You might want to review what phase shift is. These videos are
targeted at someone who wants to buy a start cap and put it in.
They don't describe the physics involved, they just use vague
terms like the cap assists the motor in starting.

I know what phase shifting is, thanks. And, I was completely off base
with the comparison as I said, several times now. It wasn't the best
comparison I could have used for the purpose, but the idea behind the
selected comparison is this: Your mains (battery for car example) or
panel for your house isn't being taxed hard to supply the required
startup power when a start cap is put into play. That's really all I
intended to convey with the poorly chosen example.

It's actually giving it a phase shift to provide the correct
rotating field. It's not really what I'd call a "boost".

Fair enough. Is it easier to just say it gives it a boost, or try to
explain what it's actually doing to a lay person? By lay person, I
mean someone who can't even find the travelers on a 3way switch
without wiring it up several different ways, several times.




--
MID:
Hmmm. I most certainly don't understand how I can access a copy of a
zip file but then not be able to unzip it so I can watch it. That
seems VERY clever!
http://al.howardknight.net/msgid.cgi?ID=145716711400

On Tuesday, August 30, 2016 at 6:03:52 PM UTC-4, Diesel wrote:
trader_4
Tue, 30
Aug 2016 15:08:14 GMT in alt.home.repair, wrote:

Neither am I. The above is specific to either a run cap or a
start cap. Neither has any charge on it prior to throwing the
switch to apply power to the motor. The point is there is no
energy there prior to that, no reservoir, to
aid in starting the motor. You compared it to a cap at an
amplifier in a car. That is very different, because there it's a
DC circuit and the cap is fully charged and available to supply
instantaneous current needs instead of it all having to come from
the battery which is located many feet away, through the impedance
of that wire.

I agree, bad comparison on my part. When using AC it's phase
shifting. When using DC, it's holding and dumping it's charge. For
simplicty sake, I just say it boosts them and don't go further into
the specific details. One (DC) actually does boost and the other
assists it with a phase shift (so not technically a boost, but, it
does cause less of a startup drain on the panel and the motor comes
up to speed quickly)

I also clearly messed up the explanation when I said the start cap
holds a charge (I was confusing it for the DC type which is what I
have more hands one experience with) and dumps it into the AC motor.
My apologies. That's what I get for playing on usenet on little
sleep. [g]

The AC compressor is an AC motor and it uses the phase shift
that a cap provides to help create the proper rotating magnetic
field. The two uses are very different. That is all that I'm
saying.

Understood.

You specifically compared it to a cap in a car amplifier, which is
a DC circuit. The function of the cap there is completely
different than how it works in an AC motor.

I agree. it was a **** poor comparison on my part. And I should have
been much more specific. I should also have started that when used in
the AC start method, it's phase shifting; so, you're right, not
technically a 'boost', but essentially in laymens terms, it is. The
motor comes up to speed quickly and doesn't draw down an excessive
amount of amps to do it, with the start caps help.

You might want to review what phase shift is. These videos are
targeted at someone who wants to buy a start cap and put it in.
They don't describe the physics involved, they just use vague
terms like the cap assists the motor in starting.

I know what phase shifting is, thanks. And, I was completely off base
with the comparison as I said, several times now. It wasn't the best
comparison I could have used for the purpose, but the idea behind the
selected comparison is this: Your mains (battery for car example) or
panel for your house isn't being taxed hard to supply the required
startup power when a start cap is put into play. That's really all I
intended to convey with the poorly chosen example.

It's actually giving it a phase shift to provide the correct
rotating field. It's not really what I'd call a "boost".

Fair enough. Is it easier to just say it gives it a boost, or try to
explain what it's actually doing to a lay person? By lay person, I
mean someone who can't even find the travelers on a 3way switch
without wiring it up several different ways, several times.



Excellent, glad to see we're all in agreement.