I put the circuit on slightly bigger breakers and tried again. The
result is that my phase converter (17.5 HP idler capacity) is not big
enough to restart the compressor when PSI reaches 100. I do not suspect
unloaders, based on what I hear when it starts, unloaders do work.

This time motor overloads tripped, quite rightly. I would not try to
defeat them. The motor clearly was not doing well.

i

Ignoramus20839 wrote:
I put the circuit on slightly bigger breakers and tried again. The
result is that my phase converter (17.5 HP idler capacity) is not big
enough to restart the compressor when PSI reaches 100. I do not suspect
unloaders, based on what I hear when it starts, unloaders do work.

This time motor overloads tripped, quite rightly. I would not try to
defeat them. The motor clearly was not doing well.

i
If the pressure makes a difference, then the unloaders are NOT
working, in some manner or other. Can you hear the unloaders
cut out after the compressor spins up? There should be a VERY
pronounced change in the sound of the compressor. Mostly it
should make a whirring when unloaded, that changes to a deep
rumble when loaded. Possibly, your phase converter is taking
too long to start such a big motor with heavy inertia of the
flywheel. You want the unloaders to wait until the compressor
is fully up to speed, so the motor doesn't have to fight inertia
plus pressure. The different sound my compressor makes can
easily be heard rooms away when it switches between loaded and
unloaded. (Actually, mine might be different, there are two
pistons 180 degrees apart in rotation, and they are connected to
one air filter. So, when unloaded, the air mostly shuttles back
and forth between the two cylinders. Yours has a separate
filter on each bank. So, it may still hum when unloaded, but
the sound should get much louder/sharper when it is compressing.)

As for the overloads, you might check the voltage and line
current, and see if your converter is holding up the generated
phase under the heavy load, or if it is allowing the voltage to
sag. A single-phase start will be REAL tough on a compressor load.

Jon

Ignoramus20839 wrote:

I put the circuit on slightly bigger breakers and tried again. The
result is that my phase converter (17.5 HP idler capacity) is not big
enough to restart the compressor when PSI reaches 100. I do not suspect
unloaders, based on what I hear when it starts, unloaders do work.


Will the motor take an empty tank up to desired pressure w/o exceeding FLA
rating motor? Is FLA inside your phase converters capacity?

If so, you need to look at unloader system.

Wes

On 2007-10-26, Jon Elson wrote:
Ignoramus20839 wrote:
I put the circuit on slightly bigger breakers and tried again. The
result is that my phase converter (17.5 HP idler capacity) is not big
enough to restart the compressor when PSI reaches 100. I do not suspect
unloaders, based on what I hear when it starts, unloaders do work.

This time motor overloads tripped, quite rightly. I would not try to
defeat them. The motor clearly was not doing well.

i
If the pressure makes a difference, then the unloaders are NOT
working, in some manner or other. Can you hear the unloaders
cut out after the compressor spins up?

It is not able to fully spin up when unloaders kick in. That's the
issue. It starts spinning, accelerates slowly, then unloaders kick in,
and it slows down, then it blows the overload.

There should be a VERY pronounced change in the sound of the
compressor. Mostly it should make a whirring when unloaded, that
changes to a deep rumble when loaded.

Exactly.

Possibly, your phase converter is taking too long to start such a
big motor with heavy inertia of the flywheel.

You are spot on.

You want the unloaders to wait until the compressor is fully up to
speed, so the motor doesn't have to fight inertia plus pressure.
The different sound my compressor makes can easily be heard rooms
away when it switches between loaded and unloaded. (Actually, mine
might be different, there are two pistons 180 degrees apart in
rotation, and they are connected to one air filter. So, when
unloaded, the air mostly shuttles back and forth between the two
cylinders. Yours has a separate filter on each bank. So, it may
still hum when unloaded, but the sound should get much
louder/sharper when it is compressing.)

Are unloaders adjustable?

As for the overloads, you might check the voltage and line
current, and see if your converter is holding up the generated
phase under the heavy load, or if it is allowing the voltage to
sag. A single-phase start will be REAL tough on a compressor load.

I am sure that the phase converter does not give enough 3rd leg
voltage. I also feel that a little more idler capacity will make a
differencwe. I could check, but I see little point, as I will be
mounting an electronic drive on it anyway, hopefuly this weekend.

i

On 2007-10-26, Wes wrote:
Ignoramus20839 wrote:

I put the circuit on slightly bigger breakers and tried again. The
result is that my phase converter (17.5 HP idler capacity) is not big
enough to restart the compressor when PSI reaches 100. I do not suspect
unloaders, based on what I hear when it starts, unloaders do work.


Will the motor take an empty tank up to desired pressure

Yes, if it starts, it pumps to 150 PSI and stops properly as directed
by the regulator.

w/o exceeding FLA rating motor? Is FLA inside your phase converters
capacity?

Yes, running is OK, but starting loaded is not.

If so, you need to look at unloader system.

If I could adjust it somehow to close valves not 2 seconds, but 5-10
seconds into the run, I think that I would be fine.

i

Ignoramus3971 wrote:

If I could adjust it somehow to close valves not 2 seconds, but 5-10
seconds into the run, I think that I would be fine.

I suspect your unloader sees head pressure coming up while not connected to
tank so you are bleeding air as the compressor pumps. Eventually, as the
head comes up to operating speed, the rate of venting can't keep up with the
increasing rate of flow causing enough pressure to be developed to shut off
venting and directly couple head to tank. Ed may need to do a rewrite on
this

I'm thinking an electric valve and electronic timer in place of the head
pressure sensing stuff that directly operates whatever valve connects tank
to head. A guy into pneumatics could use a pneumatic timer too.

Wes

Wes fired this volley in
:

I'm thinking an electric valve and electronic timer in place of the
head pressure sensing stuff that directly operates whatever valve
connects tank to head. A guy into pneumatics could use a pneumatic
timer too.


I'm thinking all you have to do is drill out the relief oriface so that
the unloader doesn't close until a much larger airflow is felt.
Alternatively, you could try a stronger spring on the poppet.

My shop compressor is a home-built with a Quincy head. It has a
conventional unloader, and never struggles to start. For construction
work, I have a portable Emglo with a "protracted open" unloader. The
compressor is one of those high-speed types with a small motor, and needs
to come up to speed before it can develop enough torque to run at
pressure. The unloader doesn't close until the motor is almost at full
rpms.

LLoyd

On 2007-10-26, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote:
Wes fired this volley in
:

I'm thinking an electric valve and electronic timer in place of the
head pressure sensing stuff that directly operates whatever valve
connects tank to head. A guy into pneumatics could use a pneumatic
timer too.


I'm thinking all you have to do is drill out the relief oriface so that
the unloader doesn't close until a much larger airflow is felt.
Alternatively, you could try a stronger spring on the poppet.

I am thinking I should just install that 25 HP electronic drive. If I
was stuck with a phase converter, I would just add another idler.

i

On Fri, 26 Oct 2007 07:25:53 -0500, with neither quill nor qualm,
Ignoramus3971 quickly quoth:

On 2007-10-26, Jon Elson wrote:
Ignoramus20839 wrote:
I put the circuit on slightly bigger breakers and tried again. The
result is that my phase converter (17.5 HP idler capacity) is not big
enough to restart the compressor when PSI reaches 100. I do not suspect
unloaders, based on what I hear when it starts, unloaders do work.

This time motor overloads tripped, quite rightly. I would not try to
defeat them. The motor clearly was not doing well.

i
If the pressure makes a difference, then the unloaders are NOT
working, in some manner or other. Can you hear the unloaders
cut out after the compressor spins up?

It is not able to fully spin up when unloaders kick in. That's the
issue. It starts spinning, accelerates slowly, then unloaders kick in,
and it slows down, then it blows the overload.

I understand that it uses hydraulic unloaders. Perhaps they have grime
or jelled oil around them and simply need to be cleaned. I've never
even seen the style, but that's the direction I'd look, FWIW.

--
Jewish Zen:
Be here now. Be someplace else later. Is that so complicated, already?
------------------------------------------------------------------------
www.diversify.com - Uncomplicated Website Design, here and now.

On Fri, 26 Oct 2007 13:23:04 -0000, with neither quill nor qualm,
"Lloyd E. Sponenburgh" lloydspinsidemindspring.com quickly quoth:

I'm thinking all you have to do is drill out the relief oriface so that
the unloader doesn't close until a much larger airflow is felt.

If it were a Chiwanese hunka arn, I might agree. But it's a Quincy.
I'd trust their engineers to come up with the best setup. Methinks
it's a maintenance issue rather than a design issue. YMMV


Alternatively, you could try a stronger spring on the poppet.

Wouldn't that cause undue wear and tear on the components? (unless the
original spring was weakened somehow)

--
Jewish Zen:
Be here now. Be someplace else later. Is that so complicated, already?
------------------------------------------------------------------------
www.diversify.com - Uncomplicated Website Design, here and now.

On 2007-10-26, Larry Jaques novalidaddress@di wrote:
On Fri, 26 Oct 2007 07:25:53 -0500, with neither quill nor qualm,
Ignoramus3971 quickly quoth:

On 2007-10-26, Jon Elson wrote:
Ignoramus20839 wrote:
I put the circuit on slightly bigger breakers and tried again. The
result is that my phase converter (17.5 HP idler capacity) is not big
enough to restart the compressor when PSI reaches 100. I do not suspect
unloaders, based on what I hear when it starts, unloaders do work.

This time motor overloads tripped, quite rightly. I would not try to
defeat them. The motor clearly was not doing well.

i
If the pressure makes a difference, then the unloaders are NOT
working, in some manner or other. Can you hear the unloaders
cut out after the compressor spins up?

It is not able to fully spin up when unloaders kick in. That's the
issue. It starts spinning, accelerates slowly, then unloaders kick in,
and it slows down, then it blows the overload.

I understand that it uses hydraulic unloaders. Perhaps they have grime
or jelled oil around them and simply need to be cleaned. I've never
even seen the style, but that's the direction I'd look, FWIW.


The point is, unloaders do work. But the compressor does not have
enough time to accelerate with my phase converter, until they rightly
kick in. It accelerates, but not fully, and then they kick in in 2
seconds and it stops.

i

Ignoramus3971 wrote:
It is not able to fully spin up when unloaders kick in. That's the
issue. It starts spinning, accelerates slowly, then unloaders kick in,
and it slows down, then it blows the overload.

Are unloaders adjustable?

Well, it depends on how the things work. In most systems, air
pressure operates the unloader. Apply air pressure, and a pin
drops down into the intake port and tips the valve disc to hold
the intake valve open. On many of the larger Quincy's, the
unloader is operated by a valve that is controlled by oil pressure.
That valve has to cut off air supply and then bleed the pressure
off the unloaders to make the compressor start pumping. If you
can find where the air escapes when the valve releases the air,
and put an orifice there, you should be able to delay the
loading of the compressor. The Quincy hydraulic unloader
control valve # 110827 (may not be similar to the one on your
compressor) has a 1/4" NPT oil port, and a 1/8" NPT air supply
port opposite it. It has a 1/8" NPT outlet to the unloaders on
the side. Opposite that is a slanted passage marked "vent" on
the drawing. You might be able to epoxy a thin brass tube to
the vent, and then attach a needle valve to the brass tube to
get the delay you need. If your phase converter takes too long
to spin it up, my guess is the VFD won't be able to go a whole
lot faster. On the other hand, it could manage a nice
acceleration with perfect phase balance, so that the overloads
don't trip. (You wouldn't have the overloads conneced, anyway,
as the VFD can sense an overload.)

Jon

Lloyd E. Sponenburgh wrote:
I'm thinking all you have to do is drill out the relief oriface so that
the unloader doesn't close until a much larger airflow is felt.
Alternatively, you could try a stronger spring on the poppet.
I haven't seen an airflow-controlled unloader control on a
Quincy. Most of the larger ones have a hydraulically-activated
air valve. When oil pressure comes up, then the pressurized air
that is holding the intake valves open is released.

Jon

On 2007-10-26, Jon Elson wrote:
Ignoramus3971 wrote:
It is not able to fully spin up when unloaders kick in. That's the
issue. It starts spinning, accelerates slowly, then unloaders kick in,
and it slows down, then it blows the overload.

Are unloaders adjustable?

Well, it depends on how the things work. In most systems, air
pressure operates the unloader. Apply air pressure, and a pin
drops down into the intake port and tips the valve disc to hold
the intake valve open. On many of the larger Quincy's, the
unloader is operated by a valve that is controlled by oil pressure.
That valve has to cut off air supply and then bleed the pressure
off the unloaders to make the compressor start pumping. If you
can find where the air escapes when the valve releases the air,
and put an orifice there, you should be able to delay the
loading of the compressor. The Quincy hydraulic unloader
control valve # 110827 (may not be similar to the one on your
compressor) has a 1/4" NPT oil port, and a 1/8" NPT air supply
port opposite it. It has a 1/8" NPT outlet to the unloaders on
the side. Opposite that is a slanted passage marked "vent" on
the drawing. You might be able to epoxy a thin brass tube to
the vent, and then attach a needle valve to the brass tube to
get the delay you need. If your phase converter takes too long
to spin it up, my guess is the VFD won't be able to go a whole
lot faster. On the other hand, it could manage a nice
acceleration with perfect phase balance, so that the overloads
don't trip. (You wouldn't have the overloads conneced, anyway,
as the VFD can sense an overload.)

Jon, the oil pressure can be only sensed in pressure lubricated
compressors, right? Mine is splash lubricated.

I have some strange attachment near the pump where some thin copper
lines go, which is separate from the regulator switch. I think that it
is the unloader adjustment thingy, but I do not know how to operate
it. I can take some pictures.

the drive, I think that a 25 HP rated drive should accelerate the
10 HP motor just fine, not much slower than actual 3 phase power. I
will probably know by Sunday.

Indeed I will not have overloads, however, I will probably mount a
fused disconnect in before the VFD, as a CYA measure.

i

In article ,
Ignoramus7291 wrote:

On 2007-10-26, Larry Jaques novalidaddress@di wrote:
On Fri, 26 Oct 2007 07:25:53 -0500, with neither quill nor qualm,
Ignoramus3971 quickly quoth:

On 2007-10-26, Jon Elson wrote:
Ignoramus20839 wrote:
I put the circuit on slightly bigger breakers and tried again. The
result is that my phase converter (17.5 HP idler capacity) is not big
enough to restart the compressor when PSI reaches 100. I do not suspect
unloaders, based on what I hear when it starts, unloaders do work.

This time motor overloads tripped, quite rightly. I would not try to
defeat them. The motor clearly was not doing well.

i
If the pressure makes a difference, then the unloaders are NOT
working, in some manner or other. Can you hear the unloaders
cut out after the compressor spins up?

It is not able to fully spin up when unloaders kick in. That's the
issue. It starts spinning, accelerates slowly, then unloaders kick in,
and it slows down, then it blows the overload.

I understand that it uses hydraulic unloaders. Perhaps they have grime
or jelled oil around them and simply need to be cleaned. I've never
even seen the style, but that's the direction I'd look, FWIW.


The point is, unloaders do work. But the compressor does not have
enough time to accelerate with my phase converter, until they rightly
kick in. It accelerates, but not fully, and then they kick in in 2
seconds and it stops.

Will Quincy sell or give you the service manual? Might be worthwhile.

Joe Gwinn

Just for the heck of it, did you check the crankcase oil level? On an old
compressor with worn rings can allow a lot of water buildup in the sump,
which also whips up the oil into goo, and can hinder the movement of the
pistons.

Tony

"Ignoramus20839" wrote in message
...
I put the circuit on slightly bigger breakers and tried again. The
result is that my phase converter (17.5 HP idler capacity) is not big
enough to restart the compressor when PSI reaches 100. I do not suspect
unloaders, based on what I hear when it starts, unloaders do work.

This time motor overloads tripped, quite rightly. I would not try to
defeat them. The motor clearly was not doing well.

i

On Fri, 26 Oct 2007 10:03:33 -0500, with neither quill nor qualm,
Ignoramus7291 quickly quoth:

On 2007-10-26, Larry Jaques novalidaddress@di wrote:

I understand that it uses hydraulic unloaders. Perhaps they have grime
or jelled oil around them and simply need to be cleaned. I've never
even seen the style, but that's the direction I'd look, FWIW.

The point is, unloaders do work. But the compressor does not have
enough time to accelerate with my phase converter, until they rightly
kick in. It accelerates, but not fully, and then they kick in in 2
seconds and it stops.

Then you've already determined that it's a motor/timing problem.
Is there any adjustment possible on the unloader timing? Orifice
change or something? Have you talked directly to the guys at Quincy
about it?

--
Jewish Zen:
Be here now. Be someplace else later. Is that so complicated, already?
------------------------------------------------------------------------
www.diversify.com - Uncomplicated Website Design, here and now.