supplying accurate output voltage < input voltage

On Jun 15, 6:02 pm, Laurav &lt;p...@cyberspace.org&gt; wrote:
On Jun 15, 8:58 pm, Jamie

jamie_ka1lpa_not_valid_after_ka1l...@charter.net&gt; wrote:
  Yes, I hear you and still, it is a mass air flow and motor design
problem..

I haven't noticed that the motor speed is sensitive to anything else
besides voltage, and the guy who makes the motor says that's the only
thing that causes changes in speed.
You could send your suggestions to Turbine Products, see what he says.
In any case I need to deal with this particular motor, not some future
verarsion.
Click to expand...
Have you considered that Turbine Products, whatever that may be, have
sold you a piece of unusable garbage? Why are they not modifying their
equipment to make it usable? Or at least providing you the
applications support that you are seeking here? They're responsible
for the halfassed design of this POS.
 
"Laurav" &lt;pbbl@cyberspace.org&gt; wrote in message
news:da6258ee-6447-4d1f-b700-766b5e0affd3@r3g2000yqh.googlegroups.com...
On Jun 15, 11:10 pm, Bennett &lt;bjpr...@cal.berkeley.edu&gt; wrote:

BTW, what is an Air Turbine; what does it do?
Click to expand...
It pushes air through a long hose to an airline respirator. So unlike
a fan, it's pushing a small amount of air, 4-5 CFM typically, but high
pressure is needed to push the air.
Really, the people who are criticizing the motor design should send
their ideas to Turbine Products. I'd be interested to hear what he
has to say.
Laura


_______

Do you have a link to any additional information, pictures, specs, etc.?
 
On Fri, 15 Jun 2012 18:02:58 -0700 (PDT), Laurav &lt;pbbl@cyberspace.org&gt;
wrote:

On Jun 15, 8:58 pm, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net&gt; wrote:

  Yes, I hear you and still, it is a mass air flow and motor design
problem..

I haven't noticed that the motor speed is sensitive to anything else
besides voltage, and the guy who makes the motor says that's the only
thing that causes changes in speed.
You could send your suggestions to Turbine Products, see what he says.
In any case I need to deal with this particular motor, not some future
version.
Laura
Greetings Laura,
Click to expand...
Can you supply any info on the motor itself? Not the current draw but
the type of motor? Maybe a picture of the motor? I suspect it is a
shaded pole motor. Also, you wrote about a rheostat controlling the
motor speed. Is that all there is to control the motor speed? Just a
variable resistor like a volume control in a radio?
Thanks,
Eric
 
On Jun 15, 11:10 pm, Bennett &lt;bjpr...@cal.berkeley.edu&gt; wrote:

BTW, what is an Air Turbine; what does it do?
Click to expand...
It pushes air through a long hose to an airline respirator. So unlike
a fan, it's pushing a small amount of air, 4-5 CFM typically, but high
pressure is needed to push the air.
Really, the people who are criticizing the motor design should send
their ideas to Turbine Products. I'd be interested to hear what he
has to say.
Laura
 
On Jun 15, 11:10 pm, Bennett &lt;bjpr...@cal.berkeley.edu&gt; wrote:

BTW, what is an Air Turbine; what does it do?
Click to expand...
It pushes a small airflow, like 4-6 CFM, through a long hose to a
respirator. It needs to generate a lot of pressure to push the air,
unlike a fan.
Laura
 
The following sounds sarcastic, but the question is unavoidable...

WHY does the flow have to be so precisely regulated? Are you worried about
bursting the lungs of the person on the respirator?

It would be much easier to have the turbine run at a constant speed and use
a simple valve at the patient's end to bleed off excess flow. (Of course, if
respirators were made that way, we wouldn't be discussing how to regulate
the turbine speed.)
 
WHY does the flow have to be so precisely regulated? Are
you worried about bursting the lungs of the person on the
respirator?

Because the motor is too noisy at high speed. Yes, excess
flow passes through a valve to the outside.
Click to expand...
Okay. Then why is such tight regulation required?
 
On Jun 16, 12:57 am, e...@whidbey.com wrote:
Can you supply any info on the motor itself? Not the current draw but
the type of motor?
Click to expand...
He said it's a universal motor. It has brushes.
It would be enough to control the input voltage, that's what I'm now
trying to do by hand. I think if I were standing by the rheostat all
the time, I could control the motor speed well enough.
It's in a metal box, I don't know what's inside the box.
What Jamie seemed to be saying is that there's some kind of feedback
loop that might make the motor very voltage-sensitive, that he said
would apply to a fan motor. This isn't a fan, it's an air turbine.
In any case, this is what I have, and what I'd like to get running
more evenly.
It's not like there are a huge variety of airline respirators on the
market. I'm not sure if the very expensive NIOSH-certified ones have
more sophisticated motor control or not. I somewhat doubt it - I
called one company and he said the innards were about the same for his
NIOSH-certified version vs the home use version.
These airline respirators are used by auto body workers or hobbyists,
sandblasters, etc. Precise volume control might not be necessary for
them.
The voltage at an outlet does seem to vary more than the utility co.
voltage, so I may have electrical problems that can be fixed and would
give more even airflow.
Laura
 
Here's what the guy who makes the respirator said, relevant to voltage
sensitivity:
"the motor speed change should be proportional to the voltage change,
but that effect is amplified by the lowering of static pressure and
the head loss in the air line, so the air flow reduction at free flow
(at the air pump with no hose) would be reduced even more if measured
at the end of the air hose."
 
On Jun 16, 9:45 am, "William Sommerwerck" &lt;grizzledgee...@comcast.net&gt;
wrote:

WHY does the flow have to be so precisely regulated? Are you worried about
bursting the lungs of the person on the respirator?
Click to expand...
Because the motor is too noisy at high speed. Yes, excess flow passes
through a valve to the outside.

Laura
 
On Jun 15, 8:51 pm, Laurav &lt;p...@cyberspace.org&gt; wrote:
On Jun 15, 11:10 pm, Bennett &lt;bjpr...@cal.berkeley.edu&gt; wrote:

BTW, what is an Air Turbine; what does it do?

It pushes air through a long hose to an airline respirator.  So unlike
a fan, it's pushing a small amount of air, 4-5 CFM typically, but high
pressure is needed to push the air.
Really, the people who are criticizing the motor design should send
their ideas to Turbine Products.  I'd be interested to hear what he
has to say.
Click to expand...
You are the only person here who is their customer. You have a
contractual relationship. You have a legitimate complaint with the
product you gave them your hardearned money in exchange. Any queries a
merely curious third party -- like the posters here -- might have can
be safely ignored.
 
On Jun 16, 6:15 am, Laurav &lt;p...@cyberspace.org&gt; wrote:
On Jun 16, 12:57 am, e...@whidbey.com wrote:

Can you supply any info on the motor itself? Not the current draw but
the type of motor?

He said it's a universal motor.  It has brushes.
It would be enough to control the input voltage, that's what I'm now
trying to do by hand.  I think if I were standing by the rheostat all
the time, I could control the motor speed well enough.
It's in a metal box, I don't know what's inside the box.
What Jamie seemed to be saying is that there's some kind of feedback
loop that might make the motor very voltage-sensitive, that he said
would apply to a fan motor.  This isn't a fan, it's an air turbine.
In any case, this is what I have, and what I'd like to get running
more evenly.
It's not like there are a huge variety of airline respirators on the
market.  I'm not sure if the very expensive NIOSH-certified ones have
more sophisticated motor control or not.  I somewhat doubt it - I
called one company and he said the innards were about the same for his
NIOSH-certified version vs the home use version.
These airline respirators are used by auto body workers or hobbyists,
sandblasters, etc.  Precise volume control might not be necessary for
them.
Click to expand...
So it's OK if something designed to protect human life works like
crap? I'm not sure how they figured that that was OK.

The voltage at an outlet does seem to vary more than the utility co.
voltage, so I may have electrical problems that can be fixed and would
give more even airflow.
Laura
Click to expand...
You said that the speed varied completely within a 20 VAC range --
100-120VAC -- that the input voltage was critical to fan speed.
Turbine Products did not design a product to cope with normal voltage
fluctuations, which can easily be +/-10%.

Is this UL approved? Is there some safety standard it's supposed to
comply with? Have you contacted NIOSH to tell them of your complaint?
 
Actually the other brands of airline respirators that I looked at
don't even have a volume control. They just push air at a very high
volume. Very loud.
Laura
 
On Jun 16, 10:53 am, "William Sommerwerck"
&lt;grizzledgee...@comcast.net&gt; wrote:

Okay. Then why is such tight regulation required?
Click to expand...
Because it's noisy at high speed. Both inside and outside the mask.
 
Laurav wrote:

Here's what the guy who makes the respirator said, relevant to voltage
sensitivity:
"the motor speed change should be proportional to the voltage change,
but that effect is amplified by the lowering of static pressure and
the head loss in the air line, so the air flow reduction at free flow
(at the air pump with no hose) would be reduced even more if measured
at the end of the air hose."
Click to expand...
If you remove the load from a series wound motor (universal), it'll
increase in RPM's, greatly in many cases.

That type of motor is very sensitive to supply and exhaust flow..

essentially, you have a vacuum loader/cleaner motor.. The only way
to properly regulate that is to measure the air mass flow and use that
as the feed back. RPM's is going to vary to maintain flow.

In a series wound motor, like you have, it is almost a natural.

P.S.
They make Brushless vacuum/blower motors that produce high volumes
with integrated electronics for speed control of a simple 0..10 volts.

They just cost more... Are you getting the image now?

http://www.grainger.com/Grainger/DOMEL-Brushless-DC-Blower-5DVY4?Pid=search

That is the idea of what I am talking about, however, that unit there
is far to large for what you're talking about. You seem to think what
you have is some high volume unit? It is actually very small compared to
what I deal with. In your case, I can understand why. You don't need to
be over inflated! ;)

Seeing that this is a medical device you have, I don't see you getting
much help from those that cold make that unit more suitable for your
needs, even though there are many that can do it for you. I think you
understand what I am talking about there, it's to bad but that has what
the world has turned to.

Personally, I can't believe they put in a universal motor, in the
first place? You need to keep an eye on the brushes! They don't last
like you think they should. It's called cheap, cheap!...

Jamie
 
On 6/15/2012 5:29 AM, Laurav wrote:
Can one get a control where you can specify the output AC voltage very
accurately, even though the input voltage isn't accurate?
It would be for input to my air turbine. The air turbine always needs
input voltage much lower than the line voltage. So the control
wouldn't need step-up circuitry.
With the rheostat that comes with my air turbine, it's very sensitive
to changes in the line voltage.
So I was thinking about bypassing the rheostat instead of buying a
power conditioner and trying to supply very accurate voltage to the
rheostat.
Laura

I wonder whether a viable alternative is to control the air pressure
Click to expand...
rather than the voltage. Set the turbine output somewhat high and let
an air pressure controller deliver the correct pressure to the mask.

Take a look at, e.g.,
http://www.regulatorstore.com/
http://www.controlair.com/index.php/regulatorproducts

I wouldn't worry too much about the motor's brushes wearing out too
quickly. Lots of home appliances (vacuum cleaner, blender, hair dryer,
coffee grinder) have brushes and last for years (albeit with
intermittent duty).
 
Bennett wrote:

On 6/15/2012 5:29 AM, Laurav wrote:

Can one get a control where you can specify the output AC voltage very
accurately, even though the input voltage isn't accurate?
It would be for input to my air turbine. The air turbine always needs
input voltage much lower than the line voltage. So the control
wouldn't need step-up circuitry.
With the rheostat that comes with my air turbine, it's very sensitive
to changes in the line voltage.
So I was thinking about bypassing the rheostat instead of buying a
power conditioner and trying to supply very accurate voltage to the
rheostat.
Laura

I wonder whether a viable alternative is to control the air pressure
rather than the voltage. Set the turbine output somewhat high and let
an air pressure controller deliver the correct pressure to the mask.

Take a look at, e.g.,
http://www.regulatorstore.com/
http://www.controlair.com/index.php/regulatorproducts

I wouldn't worry too much about the motor's brushes wearing out too
quickly. Lots of home appliances (vacuum cleaner, blender, hair dryer,
coffee grinder) have brushes and last for years (albeit with
intermittent duty).


She needs a Dyson Air multiplier :)
Click to expand...

Jamie
 
On Jun 15, 11:10 pm, Bennett &lt;bjpr...@cal.berkeley.edu&gt; wrote:
They are pretty expensive - $350 and up.  Output voltage usually not
adjustable; the built in rheostat that you've got would adjust the voltage.
Click to expand...
About how much would a UPS cost that regulates output voltage within
1% ?
The turbine uses about 1-2 A on the usual setting. On the highest
setting it uses 9 A, but I never use it that high.
Laura
 
On Jun 16, 12:24 pm, Laurav &lt;p...@cyberspace.org&gt; wrote:
On Jun 15, 11:10 pm, Bennett &lt;bjpr...@cal.berkeley.edu&gt; wrote:

They are pretty expensive - $350 and up.  Output voltage usually not
adjustable; the built in rheostat that you've got would adjust the voltage.

About how much would a UPS cost that regulates output voltage within
1% ?
The turbine uses about 1-2 A on the usual setting.  On the highest
setting it uses 9 A, but I never use it that high.
Laura
Click to expand...
ps Can anyone point me to such a UPS?
thanks
 
On Jun 16, 9:25 am, Laurav &lt;p...@cyberspace.org&gt; wrote:
On Jun 16, 12:24 pm, Laurav &lt;p...@cyberspace.org&gt; wrote:

On Jun 15, 11:10 pm, Bennett &lt;bjpr...@cal.berkeley.edu&gt; wrote:

They are pretty expensive - $350 and up.  Output voltage usually not
adjustable; the built in rheostat that you've got would adjust the voltage.

About how much would a UPS cost that regulates output voltage within
1% ?
The turbine uses about 1-2 A on the usual setting.  On the highest
setting it uses 9 A, but I never use it that high.
Laura

ps Can anyone point me to such a UPS?
thanks
Click to expand...
didn't see any specific responses, so

try search for UPS in the 200+VA range, to be certain it'll give no
problems find something 400+ VA that is constantly running.

When you find something that you 'think' might work within budget;
post a URL here and everyone will look at it and give excellent
critiques.

Then you can buy it and be done with it.
 
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