Packing line upgrade time...
My bin dump water pump is the largest noise maker in the system. I
quickly tried a VFD a couple years ago and it SQUEALED far worse than
the excess motor noise. Just as pleasant as listening to chalk squeal
on a blackboard.
Anyway, this time I want to buy a 1/2 hp VFD that doesn't have carrier
wave noise. Suggestions? BTW, the unit will be located 75' of wire
from the motor. Is a reactor needed in this case?
Like Gunner said, and you implied, I just had bad luck last time. i
also have many VFDs with no noise. But, this is a much quiter level,
trying to get less noise than a dot matrix printer.
The problem was two years ago, maybe more. Folks on this group said it
was carrier wave and I seem to remember reactor being suggested. But
my memory sux and maybe who ever said it was full of beans.
Anyway, should i pop for a reactor? I've bought from automation direct
before with good results.
If the squeal is coming from the motor itself, the reactor(s) will help
smooth the 'simulated sine wave' coming out of the inverter drive.
Good VFD's divide the stepped waveform up into small enough slices so
that the noise is of a high enough frequency not to be heard by us old
men, and not annoying to anything but cats and bats and teenagers (a good
I've used the Automation Direct VFDs and also Motortronics, with which I
have had very good experience and reliability. No noise from either
On Mon, 19 Aug 2013 18:02:08 -0500, "Lloyd E. Sponenburgh"
The later Rockwells I've used had a menu item to change the carrier
frequency if noise was evident. Our vendor recommended reactors if
200' or more. Something to do with harmonics on the feed line. Mine
were usually about 10' or less. Mitsubishis I have now are quiet
except I can hear the cooling fans.
I think that the squeal is likely from loose laminations in the
stator of the motor -- and likely just right to be resonant at the
default frequency of the VFD -- so a change in frequency would likely
make a big difference. (An alternative is to force a varnish into the
laminations -- but be sure to pick one which will not attack the
varnish/enamel on the wires wound on there.) Maybe a very thin epoxy
A reactor might reduce the high frequency part getting to the
motor windings -- but is otherwise unlikely to be necessary.
A replacement motor will likely not show the same problem --
even if the same brand. But it might be the most expensive approach.
My impression has always been that the PWM frequency was simply too low on
first-generation inverters; and that while anything built within the past
couple decades might well still create some annoyong electrical noise,
acoustic emmissions will be at a frequency substantionally above the human
I don' know what the total range of human hearing is, but when I was younger
I could hear or be aware of frequencies upto about 20kz. Depending on the
sound generator somewhere between 19.5 and 20.5 I would notice it go
substantially silent. Now as I have gotten older I have noticed that I
can't hear much above about 17.5.
Anyway, the range of human varies with age, and does so noticeably with men
in the high frequency range. Also, its possible that some people have a
wider range of hearing atleast at the peak level of their physical
development. All of that being said, who knows what odd frequencies can be
generated by a VFD.
Hmmmm... I'm not sure any of that makes a point, but its some nice anecdotal
information to consider. LOL.
I used not to be comfortable in a room with a TV which had a loose
bracket on the flyback transformer. The 17.5KHz deflection frequency
literally drove me out of the room!
At 64, I can't hear much above 10KHz, and suspect that's diminishing due
to my fireworks and explosives activities (and Viet Nam, where I had an
eardrum perforated by a nearby and unexpected firing of a Browning .50).
On Wed, 21 Aug 2013 14:04:31 -0500, "Lloyd E. Sponenburgh"
Im fortunate I can still hear..mostly. I have however gotten pretty
good at lip reading most women. I can hear their voices..I just cant
make out what many say. Way above my hearing range.
I had my hearing checked by a pro a few years ago..and he had the
chart with my hearing range in his hand..he looked up at me...looked
at the chart..and said..let me guess..combat vet right?
The chart had holes in the hearing ranges all over the place. He said
only combat vets have a chart that looks like it was hit with a
shotgun a couple times..with scattered holes all over it.
Its been years since Ive heard a violin.
yep, flipped a couple of digits.
And... it was back in the BW days, when I was young enough to hear that
We didn't have color TV until about three years after I got married!
(don't say it... no, I didn't know Marconi, except by reputation!)
12:06:15 -0400 typed in rec.crafts.metalworking the following:
Some people are more "perceptive" than others. The effect of
fluorescent light bulbs for some folks is not "illumination" but
"disco strobe light" - which makes concentrating in school or at work
Tangent question - AM radio reception in a pickup truck. ('98
Mazda, EFI, manual 244000 miles)
I leave 'near' Everett WA, twenty miles as the seagull flies from
Paine Field (a bit farther if the seagull is driving and stuck in
traffic.) I cannot believe that I live so far out in the boonies,
that I can't pick up local radio stations. (At night - the two
strongest stations are in Calgary and Vancouver BC. Kind of tough to
figure the local weather from their reports - in Celsius, no less. But
Regardless, and I realize diagnosing electrical troubles by mail
is right up there with getting financial advice on the radio and other
forms of occult prognostication, I have noticed a couple things. I
get over the ridge - and past the high-tension power lines - and I can
generally get the Seattle Stations. But sometimes, especially when I
tune to ~550 AM, I get a "sound" - sort of like a marlin Brando
clearing his throat on sideband. a sort of 'pop' - gargle, 'pop' -
gargle, 'pop' - gargle,'pop' - gargle', pop' - gargle.
It isn't (as far as I can tell) related to engine speed - in fact
I can shut off the engine, energize the circuit and the radio is
clear, then pop the clutch, resume engine running - and no pop-gargle.
Also, on occasion I have "joggled" the key - returning it back to the
proper detent for "engine is running", not part way to "engage starter
solenoid!" - it has cleared up. For a while.
Now with that collection of wonderfully accurate set of technical
descriptions, no doubt you can channel the mighty psychic powers of
the Late Great Carnac and know exactly what is the source of my woes.
(Aside from the County PUD.) And what the solution is, aside from
"Plug the ipod in and listen to that instead."
thanks in advance.
"With Age comes Wisdom. Although more often, Age travels alone."
On Thu, 22 Aug 2013 11:10:05 -0700, pyotr filipivich
Try removing your instrument fuse - see if it goes away. Don't know
what kind of instrument regulator they are using theses days, byt they
used to use a thermal unit that could (and often did) make terrible
noise on AM radio. I replaced quite a few with solid state regulators
over the years. (no, the dash instruments do NOT work on 12 volts) If
the BZZ POP BZZ POP goes away with the instrument (not instrument
lighting) fuse pulled, you know where to look.
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