On Sat, 13 Sep 2008 05:41:13 -0400, ml wrote:

hi Paul

see responces below, and thanks very much

In article
,
" wrote:


so assuming * , *they let me do that, * and *my test *reveils *noise *
along the *wires * , *what *types *of snap on *chokes /material would *
be *recomened?

i wonder if they conduit is a 'poor' *shield * i could easily wrap that
w/rf tape

Hi.
I am coming into ths discussion kind of late, but see no mention as to
changes in the noise level as the elevator is operating or not. Is the
motor and control circuit live all the time or just when the elevator
is occupied or in motion.
from being inside my house i can't really tell elevator
movement, i can say the noise is constantly intermittant, that is
on a few min off a few min, it 'seems' not to correspond to
elevator movement but i'd need a second guy to prove that

However being in the elevator room, as previously mentioned w/my
ft817 i can tell you the motor and magnatek is always slightly
energized however with no elevator movement the noise is
extreemly small soo as the motor kicks in the magnatek makes a
ton of noise same test standing ontop of the motor shows little
noise i didn't test the conduit


As far as snap-on ferrite chokes, they must allow the largest wire to
pass and should be fairly large for the low frequency involved.

Perhaps this has been mentioned before, but conduit will certainly
radiate if it is not connected to a common ground point at each end.
Otherwise, it is an antenna. No amount of tape will stop that. If
connected to two "ground" points, the conduit could still radiate as a
loop antenna. The building framework may make an electrical ground,
but not an RF ground.
yea that got me thinking i noticed the manual for the magnatek
actually talked about how to keep one end only 'grounded' and the
book was very good at explaning it, i have to go back up and see if
they did that i bet they sure didn't my guess is they didn't use
shielded wire to the motor sensor i'd guess iether plain wire or if
i am luckey

they have really only an electrical ground up their they did make a
single buss on the bottom and everything terminates at least to a
single point the conduit is 'grounded' by connecting with the metal
cabinet which is connected to that elec ground my building water,
heat, Ibeams and elec ground seem to all be at same potential and do
connect with earth soil, naturally the elevator room on the roof is
14stories high

i disagree with you however that 'no ammount' of tape would help if
the conduit was radiating copper or mu-metal, or lead or RFpaint
wrapped around the conduit and possibly grounded i think would have
an effect but i could be wrong my guess is it could work why do you
think it's not possible?

Do you have a portable am shortwave radio with an external antenna?
Use it to explore (safely!) the wiring with the external antenna. I
did this at home and discovered lots of HF noise coming from a VCR,
DVD player and TV that were always on, but on standby. I think this
exercise will let you track the noise a lot easier than your expensive
ham rig.
Yes the ft817 also has am but i've been testing ssb easier on
the ears and just a strong interference hihi

yeah it's funny how sometimes you find a vcr or a cable modem
that puts out so much noise on even standbuy a lot of companies these
days really are rf poluters and seem to get away with murder

I wonder if that magnetek is legal , just say the unit by itself
is it fcc approved to radiate such a strong signal so broad ??
second to that since it is interfering with a licensed ham station
per rules and regs would it be in violation? i wonder how i
confirm that ultimately i might hve to file a complaignt





Good luck!

Paul, KD7HB

Seeing as you are trying to stop RF, using copper tape / foil and
copper screens / expanded sheet metal / densely perforated sheet metal
is the best bet for shielding approaches. Very large ferrites for
creating chokes (high motor currents). Try very large snap on
ferrites around the lead groups entering and exiting the Magnetek.
Both on individual leads and on three / (four ?) / six lead groups
headed to the motor.

On Sep 11, 2:58*pm, ml wrote:
hi

a while ago i posted * hoping to get *some *ideas *how to *eliminate *
some s9 noise caused by my buildings new elevators

only took them 9months to install * *some electrical filters *but the
guy doing it *was very nice *and *showed *me a few things

since the filters *didn't help *seemingly at all, * i wanted to provide *
some more information *and see *what *anyone might *think would be
either some *good *tests * to make and or *further corrective *actions

a recap, jan 08 *we got a new *elevator system *the original 1940's unit
was just a rack of relays *there *are 2 elevators * *motor and *stuff in
a small room * rooftop * noise was always *s0 or s1

the new *system *i can see is made by galaxy *believe it or not made in
the bronx ny *i am told they are a large world wide supplier *since i
live in the bronx *at least they are local

my first look * in there today * shows *they did *at least *take pride
in there *work, *all the wiring in there * is *really nice

there is kinda *2 main parts in the cabinet * *a large *pc board *and a *
magnetek HPV 600

i took *my ft817 *shut the other elevator *off * and *moving *the rig *
around *i see i got * no interference from the *computer board *getting
near *the magnetek * big time noise

they have the manual onlinehttp://www.elevatorcontrols.com/downloads/files/hpv600.pdf

pretty interesting * a *section in there *on how to *mitigate *noise *
perhaps a few things in there *i could *maybe double check

when noone is using the elevator *they throw *out some noise *like about *
s2 maybe *more * when the elevator *starts moving *it jumps *naturally
to about *s9

i was wondering *how *to *first see *where the noise *is leaking from *
the metal cabinet *is *pretty *think *i say double the gague *of *say a
file cabnet *, it does *have *slits *on either side *for * air * * a few *
holes *for *conduit * which runs * to the power *and to the motor *

they seemed *to pay attention to grounding * the door *had a *little *
ground *wire on it, * etc *naturally this is all *fast first impression
stuff i didn't have a lot *of time up there

i thought *perhaps * painting the cabinet w/rf paint and getting some *
screens *over the vent slits *thou obv that wouldn't help if it's *
radiating along the conduit *didn't have a chance *to measure for that

the *magnetek *is a bread sized box it gets *hot and has a fan *so i
can't *cover *it, but perhaps a perferated copper/lead *enclousure might
help?(assuming it's not *radiating along its wires)

as a last resort *perhaps *replacing the magnatek w/another brand known
to be *rf quite * *however *i personally don't *know how i would *find
that out *and *no garantee *they would *risk swaping the unit oout

so i am hoping * *that *there might be some brainstorming *and thoughts *
you all might *share?

any advice *tips * * much *appreciated

thanks for all

Elevator motors are DC, in the old one the DC was supplied by a motor/
generator combination, The new ones get their DC from a huge SMPS and
they can be electrically noisy. They can also induce harmonics into
the electrical system that UPSs dont like at all. It is my
understanding the elevator rehab project where I work has been put on
hold for that reason.

Jimmie

JIMMIE wrote:
On Sep 11, 2:58 pm, ml wrote:
hi


Elevator motors are DC, in the old one the DC was supplied by a motor/
generator combination, The new ones get their DC from a huge SMPS and
they can be electrically noisy. They can also induce harmonics into
the electrical system that UPSs dont like at all. It is my
understanding the elevator rehab project where I work has been put on
hold for that reason.

Jimmie

Modern elevators use AC induction motors with a variable speed drive.