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| Author |
Balance on 3 phase system
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|
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| I have the following situation.
We use generators supplying 120 volt 3 phase service.
At the distribution panel at the generator, ground and neutral are bonded
together.
Ground and neutral are then routed to separate service panels for different
shelters (comm) at the sites.
At the service panel for the separate shelters the ground and neutral that
come from the generator shelter are grounded inside the service panel, which
is then connected to the shelter ground bus.
Most of the load is placed on phase A, which includes both telecommunication
systems, and environmental units. Phase B takes on the overflow service
requirements, with Phase C having hardly any load on it at all.
We are seeing quite a lot of ripple on our ground, as well as on our 120v
lines. The ripple is not coming from the generator, as that ripple is well
within specs.
The ripple we are seeing is in excess of 100mv as measured with an Oscope.
This is seen on both the ground, as well as on our DC distribution hot leg.
The DC rectifier is bonded to the same ground that the incoming service
neutral is connected to. And the rectifier does show that the input 120v
voltage swings quite a bit. (in excess of 20 volts, while the 60hz phase
remains pretty stable). On my telecommunication circuits I am seeing quite a
bit of noise in excess of the 20mv usually seen.
Any ideas I what I can do to reduce this excess noise/imbalance on our 120v
service and on the ground/neutral.
The environmental units are 120 single phase systems.
| |
| Dale Farmer 2005-06-17, 11:30 pm |
|
Dana wrote:
quote:
> I have the following situation.
>
> We use generators supplying 120 volt 3 phase service.
> At the distribution panel at the generator, ground and neutral are bonded
> together.
> Ground and neutral are then routed to separate service panels for different
> shelters (comm) at the sites.
> At the service panel for the separate shelters the ground and neutral that
> come from the generator shelter are grounded inside the service panel, which
> is then connected to the shelter ground bus.
> Most of the load is placed on phase A, which includes both telecommunication
> systems, and environmental units. Phase B takes on the overflow service
> requirements, with Phase C having hardly any load on it at all.
> We are seeing quite a lot of ripple on our ground, as well as on our 120v
> lines. The ripple is not coming from the generator, as that ripple is well
> within specs.
> The ripple we are seeing is in excess of 100mv as measured with an Oscope.
> This is seen on both the ground, as well as on our DC distribution hot leg.
> The DC rectifier is bonded to the same ground that the incoming service
> neutral is connected to. And the rectifier does show that the input 120v
> voltage swings quite a bit. (in excess of 20 volts, while the 60hz phase
> remains pretty stable). On my telecommunication circuits I am seeing quite a
> bit of noise in excess of the 20mv usually seen.
> Any ideas I what I can do to reduce this excess noise/imbalance on our 120v
> service and on the ground/neutral.
> The environmental units are 120 single phase systems.
I suggest that you balance the loads more or less equally between the
three phases of the electrical service. Or get a single phase generator. My
guess is that your generator doesn't like the unbalanced load.
Next I don't see you mentioning a ground rod to the earth, this is a needful
safety precaution. I will guess that you are in the US, and thus come under
NEC rules. Other countries have different specific laws.
If you are treating each equipment shelter power panel as a building
entry panel, then you don't actually need to run a separate ground conductor
from the generator. You still need to ground the generator, and each building
entry panel to good earth ground systems. This is something you and your
local electrical inspector have to agree on.
--Dale
| |
|
|
"Dale Farmer" <dale@cybercom.net> wrote in message
news:424F8063.5FA58C2D@cybercom.net...
quote:
>
>
> Dana wrote:
>
bonded[vbcol=seagreen]
different[vbcol=seagreen]
that[vbcol=seagreen]
which[vbcol=seagreen]
telecommunication[vbcol=seagreen]
120v[vbcol=seagreen]
well[vbcol=seagreen]
Oscope.[vbcol=seagreen]
leg.[vbcol=seagreen]
quite a[vbcol=seagreen]
120v[vbcol=seagreen]
>
> I suggest that you balance the loads more or less equally between the
> three phases of the electrical service. Or get a single phase generator.
My
quote:
> guess is that your generator doesn't like the unbalanced load.
How important is it for a 3 phase system be balanced in regards to the loads
placed on it??
If we are unbalanced in regards to load distribution does that pose any
issues, besides that the generator may not like that?
quote:
> Next I don't see you mentioning a ground rod to the earth, this is a
needful
Yes we have a ground rod at the generator building, as well as at all the
shelters.
These grounds are not at the same potential, yet we have them
interconnected with grounding wires.
From the distro panel at the generator shelter as well as each comm shelter.
The distance is just over 100 feet between each shelter.
The ground is not uniform as the area is very rocky (mountain tops in
Alaska)
quote:
>
> safety precaution. I will guess that you are in the US, and thus come
under
quote:
> NEC rules.
Our engineers none of whom are licensed electricians by the state, insist
that they do not have to follow any kind of codes.
Other countries have different specific laws.
quote:
> If you are treating each equipment shelter power panel as a building
> entry panel, then you don't actually need to run a separate ground
conductor
quote:
> from the generator. You still need to ground the generator, and each
building
quote:
> entry panel to good earth ground systems. This is something you and your
> local electrical inspector have to agree on.
The electrical work performed is not inspected, nor is there any kind of QA
process involved.
This is why I am trying to find out what I may be able to do to clean up the
noise on the power and ground distribution.
I Think the noise is coming from the unbalance via the neutral to ground
bonding of our service panel, which is also attached to the ground bus
system used inside the shelter for our DC powered telecomm systems, like
microwave radios and T3 and T1 multiplexers, as well as other data comm
equipment.
We have constant current on our ground bus which is bonded to the service
panel.
quote:
>
> --Dale
>
>
| |
| Bruce Durdle 2005-06-17, 11:30 pm |
| One reason for using 3-phase generators is that a balanced three-phase
load imposes a fixed power demand on the prime mover. If the bulk of
your electrical load is on one phase, the mechanical load on the
generator engine will pulsate at 120 Hz (if you are on a 60 Hz supply).
Whether or not this will affect the engine will depend on how good the
governor and fuel control system is.
Bruce.
Dana wrote:
quote:
> "Dale Farmer" <dale@cybercom.net> wrote in message
> news:424F8063.5FA58C2D@cybercom.net...
>
>
> bonded
>
>
> different
>
>
> that
>
>
> which
>
>
> telecommunication
>
>
> 120v
>
>
> well
>
>
> Oscope.
>
>
> leg.
>
>
> quite a
>
>
> 120v
>
>
> My
>
>
>
> How important is it for a 3 phase system be balanced in regards to the loads
> placed on it??
> If we are unbalanced in regards to load distribution does that pose any
> issues, besides that the generator may not like that?
>
>
>
>
> needful
>
> Yes we have a ground rod at the generator building, as well as at all the
> shelters.
> These grounds are not at the same potential, yet we have them
> interconnected with grounding wires.
> From the distro panel at the generator shelter as well as each comm shelter.
> The distance is just over 100 feet between each shelter.
> The ground is not uniform as the area is very rocky (mountain tops in
> Alaska)
>
>
> under
>
>
>
> Our engineers none of whom are licensed electricians by the state, insist
> that they do not have to follow any kind of codes.
>
>
> Other countries have different specific laws.
>
>
> conductor
>
>
> building
>
>
>
> The electrical work performed is not inspected, nor is there any kind of QA
> process involved.
>
> This is why I am trying to find out what I may be able to do to clean up the
> noise on the power and ground distribution.
> I Think the noise is coming from the unbalance via the neutral to ground
> bonding of our service panel, which is also attached to the ground bus
> system used inside the shelter for our DC powered telecomm systems, like
> microwave radios and T3 and T1 multiplexers, as well as other data comm
> equipment.
> We have constant current on our ground bus which is bonded to the service
> panel.
>
>
>
>
>
| |
| Dale Farmer 2005-06-17, 11:30 pm |
|
Dana wrote:
quote:
> "Dale Farmer" <dale@cybercom.net> wrote in message
> news:424F8063.5FA58C2D@cybercom.net...
> bonded
> different
> that
> which
> telecommunication
> 120v
> well
> Oscope.
> leg.
> quite a
> 120v
> My
>
> How important is it for a 3 phase system be balanced in regards to the loads
> placed on it??
> If we are unbalanced in regards to load distribution does that pose any
> issues, besides that the generator may not like that?
>
You will get significant current flow on the neutral going back to the
generator, since this is connected to the ground system, some of that
voltage will contaminate your ground bus.
quote:
> needful
>
> Yes we have a ground rod at the generator building, as well as at all the
> shelters.
> These grounds are not at the same potential, yet we have them
> interconnected with grounding wires.
> From the distro panel at the generator shelter as well as each comm shelter.
> The distance is just over 100 feet between each shelter.
> The ground is not uniform as the area is very rocky (mountain tops in
> Alaska)
Earth ground is never uniform. If you are tying the different hut ground
systems together into one system, then that voltage flow will also flow back
and forth on the ground connections between the huts. In this case, I'd try
breaking the ground-nuetral tie in each hut's power panel, leaving the only
connection between neutral and ground back at the generator. You then
have to have all five wires from the generator to each hut power panel. This
will move the source of the ground currents back to the generator.
quote:
>
> under
>
> Our engineers none of whom are licensed electricians by the state, insist
> that they do not have to follow any kind of codes.
>
Write up a memo for the record stating that, and make them all sign
and notarize the document. Then send a copy to your company or
university legal department for their review. This may be legally true,
but the NEC is primarily concerned with safety. Not following the
code is asking for trouble. Hopefully the only things being damaged
is the data being collected, not the equipment or the people there.
quote:
>
> Other countries have different specific laws.
> conductor
> building
>
> The electrical work performed is not inspected, nor is there any kind of QA
> process involved.
Bad idea. Everyone has a bad day, getting another set of qualified eyeballs
looking at an installation to check for mistakes is always a good idea. I won't
share with you my stories about EEs who felt they were qualified to to work
on things and subsequently caused destruction and fires. And up there on
the mountain top, you are a loooong way from the nearest fire department
or ambulance service. You should be extra diligent in your practices because
of this isolation. Hopefully you have a couple of folks who are at least CPR
certified on the crew up there.
quote:
>
>
> This is why I am trying to find out what I may be able to do to clean up the
> noise on the power and ground distribution.
> I Think the noise is coming from the unbalance via the neutral to ground
> bonding of our service panel, which is also attached to the ground bus
> system used inside the shelter for our DC powered telecomm systems, like
> microwave radios and T3 and T1 multiplexers, as well as other data comm
> equipment.
> We have constant current on our ground bus which is bonded to the service
> panel.
Very likely. The unbalanced loads put significant current on the neutral
conductor going back to the generator. Since you have bonds between
neutral and ground at each hut and at the generator, that current also
flows on the ground cables between the huts, producing the differing
ground potentials between the hut ground systems.
Balance the electrical loads between the three hot phases. Break the
additional ground/neutral connections, leaving only the one in the generator.
Increase the size of the ground conductors between the huts. Check your
lightning protection system. You may be getting issues from cloud
potentials on a mountiantop.
--Dale
| |
|
|
"Dale Farmer" <dale@cybercom.net> wrote in message
news:42502526.5D7CE857@cybercom.net...
quote:
>
>
> Dana wrote:
>
neutral[vbcol=seagreen]
panel,[vbcol=seagreen]
service[vbcol=seagreen]
is[vbcol=seagreen]
hot[vbcol=seagreen]
service[vbcol=seagreen]
120v[vbcol=seagreen]
phase[vbcol=seagreen]
our[vbcol=seagreen]
the[vbcol=seagreen]
generator.[vbcol=seagreen]
loads[vbcol=seagreen]
>
> You will get significant current flow on the neutral going back to the
> generator, since this is connected to the ground system, some of that
> voltage will contaminate your ground bus.
This is exactly the situation I am seeing. And the data comm equipment is
using this same ground bus, I am under the impression this is where my
errors on the circuits are coming from.
quote:
>
a[vbcol=seagreen]
the[vbcol=seagreen]
shelter.[vbcol=seagreen]
>
> Earth ground is never uniform. If you are tying the different hut
ground
quote:
> systems together into one system, then that voltage flow will also flow
back
quote:
> and forth on the ground connections between the huts. In this case, I'd
try
quote:
> breaking the ground-nuetral tie in each hut's power panel, leaving the
only
quote:
> connection between neutral and ground back at the generator. You then
> have to have all five wires from the generator to each hut power panel.
This
quote:
> will move the source of the ground currents back to the generator.
Thanks.
quote:
>
insist[vbcol=seagreen]
>
> Write up a memo for the record stating that, and make them all sign
> and notarize the document. Then send a copy to your company or
> university legal department for their review. This may be legally true,
> but the NEC is primarily concerned with safety. Not following the
> code is asking for trouble. Hopefully the only things being damaged
> is the data being collected, not the equipment or the people there.
We have had equipment damage, and yes the safety issue with the power distro
at these sites is very questionable.
The engineers swapped out a rectifier that places more current onto the
building distro without increasing the size of the conductors. The existing
conductors were not rated for this kind of load, hence our power distro
lines are warm to the touch, and the fuse in the service panel was blowing,
so they bypassed the fuse.
I have lost about 5 power supplies in various equipment since this has been
done.
quote:
>
building[vbcol=seagreen]
your[vbcol=seagreen]
QA[vbcol=seagreen]
>
> Bad idea. Everyone has a bad day, getting another set of qualified
eyeballs
quote:
>
> looking at an installation to check for mistakes is always a good idea. I
won't
quote:
>
> share with you my stories about EEs who felt they were qualified to to
work
quote:
> on things and subsequently caused destruction and fires. And up there on
> the mountain top, you are a loooong way from the nearest fire department
> or ambulance service. You should be extra diligent in your practices
because
quote:
> of this isolation. Hopefully you have a couple of folks who are at least
CPR
quote:
> certified on the crew up there.
The company does give yearly CPR training. When I need to work on the power
at this remote site, I tend to turn the entire site down, and just power up
what I need to work on, as there is no individual disconnects on the circuit
feeding the different equipment, including our battery stack. This has been
the first place where I have see no way to disconnect the batteries, without
physically removing the connection on the battery stack.
quote:
>
the[vbcol=seagreen]
service[vbcol=seagreen]
>
> Very likely. The unbalanced loads put significant current on the neutral
> conductor going back to the generator. Since you have bonds between
> neutral and ground at each hut and at the generator, that current also
> flows on the ground cables between the huts, producing the differing
> ground potentials between the hut ground systems.
> Balance the electrical loads between the three hot phases. Break the
> additional ground/neutral connections, leaving only the one in the
generator.
quote:
> Increase the size of the ground conductors between the huts. Check your
> lightning protection system. You may be getting issues from cloud
> potentials on a mountiantop.
On a wireless site you would normally ground your transmission lines coming
off the tower to a ground outside the shelter, here we attach these grounds
to the inside ground bus, which all the equipment is hooked to. So any
strike on the tower, or any currents developed on the tower essentially go
to my equipment ground bus.
quote:
>
> --Dale
>
>
| |
| Dale Farmer 2005-06-17, 11:30 pm |
|
Dana wrote:
quote:
> "Dale Farmer" <dale@cybercom.net> wrote in message
> news:42502526.5D7CE857@cybercom.net...
> eyeballs
> won't
> work
> because
> CPR
>
> The company does give yearly CPR training. When I need to work on the power
> at this remote site, I tend to turn the entire site down, and just power up
> what I need to work on, as there is no individual disconnects on the circuit
> feeding the different equipment, including our battery stack. This has been
> the first place where I have see no way to disconnect the batteries, without
> physically removing the connection on the battery stack.
GOod god. This site sounds like a disaster waiting to happen. If you are
in a position to do so, I'd refuse to work on this anymore. OSHA has
jurisdiction as this is your workplace, and this place is unsafe until you have
a qualified power engineer come in and rework the power system from the
ground up.
quote:
>
> the
> service
> generator.
>
> On a wireless site you would normally ground your transmission lines coming
> off the tower to a ground outside the shelter, here we attach these grounds
> to the inside ground bus, which all the equipment is hooked to. So any
> strike on the tower, or any currents developed on the tower essentially go
> to my equipment ground bus.
>
Get a qualified lightning protection engineer up there to design a proper
protection scheme. I'm not qualified in that field, consult some of the
broadcast tower folks who have to design such things. I know that they
take great care to keep the tower ground system separate from the building
electrical safety ground. I'm amazed that you have only lost equipment. It's
only a matter of time until you burn the place down and/or kill someone.
--Dale
| |
| Dale Farmer 2005-06-17, 11:30 pm |
|
Dale Farmer wrote:
quote:
> Dana wrote:
>
>
> GOod god. This site sounds like a disaster waiting to happen. If you are
>
> in a position to do so, I'd refuse to work on this anymore. OSHA has
> jurisdiction as this is your workplace, and this place is unsafe until you have
> a qualified power engineer come in and rework the power system from the
> ground up.
>
>
> Get a qualified lightning protection engineer up there to design a proper
> protection scheme. I'm not qualified in that field, consult some of the
> broadcast tower folks who have to design such things. I know that they
> take great care to keep the tower ground system separate from the building
> electrical safety ground. I'm amazed that you have only lost equipment. It's
> only a matter of time until you burn the place down and/or kill someone.
>
> --Dale
By the way, I'd like to get some pictures of this installation if you have them.
I know a fellow who is collecting pictures of stupid electrical installations
and he puts them into his slide presentations as bad examples.
--Dale
| |
| Michael 2005-06-17, 11:30 pm |
| "Dana" <anon@noneya.com> wrote in
news:1150aogo9c8f1af@corp.supernews.com:
quote:
> We have had equipment damage, and yes the safety issue with the power
> distro at these sites is very questionable.
> The engineers swapped out a rectifier that places more current onto
> the building distro without increasing the size of the conductors. The
> existing conductors were not rated for this kind of load, hence our
> power distro lines are warm to the touch, and the fuse in the service
> panel was blowing, so they bypassed the fuse.
> I have lost about 5 power supplies in various equipment since this has
> been done.
Several things come to my mind when I read this:
- The installation was not planned with any headroom for further
extensions.
- Swapping a rectifier to a model with a higher output power without
increasing the cable size (when necessary like here) does not only
violate any regulation, but also lacks common sense.
- I would consider bypassing the fuse under such conditions as a criminal
act. Any other ideas how to call a move that overrides safety measures
and puts other people in a dangerous situation (fire hazard)?
- The fact that you lost (fortunately only) equipment due to this
installation makes it look pretty shaky.
quote:
> The company does give yearly CPR training. When I need to work on the
> power at this remote site, I tend to turn the entire site down, and
> just power up what I need to work on, as there is no individual
> disconnects on the circuit feeding the different equipment, including
> our battery stack. This has been the first place where I have see no
> way to disconnect the batteries, without physically removing the
> connection on the battery stack.
Batteries deserve uttermost respect from a handling and connection point of
vieew. The answer is simple: Tremendous short-circuit currents, fast
current rise and a serious amount of stored energy,
I planned a small lab installation of a DC power supply unit with battery
strings recently and I had to go through several standards to get approval
(now it is installed and working fine).
The point is that there is no path without fuse/switch in the installation.
There is a lot of work ahead! Good luck!
Michael
| |
| Michael 2005-06-17, 11:30 pm |
| "Dana" <anon@noneya.com> wrote in
news:114v1aup458nsc5@corp.supernews.com:
quote:
> Yes we have a ground rod at the generator building, as well as at all
> the shelters.
> These grounds are not at the same potential, yet we have them
> interconnected with grounding wires.
> From the distro panel at the generator shelter as well as each comm
> shelter. The distance is just over 100 feet between each shelter.
> The ground is not uniform as the area is very rocky (mountain tops in
> Alaska)
> under
>
> Our engineers none of whom are licensed electricians by the state,
> insist that they do not have to follow any kind of codes.
Wait - is this installation connected to a telephone network, e.g. of one
of the RBOCs? In this case is could be in conflict with NEC rules and the
safety requirements from NEBS. This could be an interesting case ...
Michael
| |
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"Dale Farmer" <dale@cybercom.net> wrote in message
news:42506992.DC28A85F@cybercom.net...
quote:
>
>
> Dale Farmer wrote:
>
qualified[vbcol=seagreen]
idea. I[vbcol=seagreen]
to[vbcol=seagreen]
there on[vbcol=seagreen]
department[vbcol=seagreen]
practices[vbcol=seagreen]
least[vbcol=seagreen]
power[vbcol=seagreen]
power up[vbcol=seagreen]
circuit[vbcol=seagreen]
been[vbcol=seagreen]
without[vbcol=seagreen]
you are[vbcol=seagreen]
you have[vbcol=seagreen]
clean up[vbcol=seagreen]
ground[vbcol=seagreen]
bus[vbcol=seagreen]
systems, like[vbcol=seagreen]
comm[vbcol=seagreen]
neutral[vbcol=seagreen]
also[vbcol=seagreen]
Break the[vbcol=seagreen]
your[vbcol=seagreen]
coming[vbcol=seagreen]
grounds[vbcol=seagreen]
essentially go[vbcol=seagreen]
proper[vbcol=seagreen]
building[vbcol=seagreen]
equipment. It's[vbcol=seagreen]
>
> By the way, I'd like to get some pictures of this installation if you have
them.
quote:
> I know a fellow who is collecting pictures of stupid electrical
installations
quote:
> and he puts them into his slide presentations as bad examples.
I will work on that. I will take my digital camera out when I go out to
these remote sites.
Thaks for the tips.
quote:
>
> --Dale
>
>
| |
|
|
"Michael" <hamtaro@muenchen-ist-toll.de> wrote in message
news:Xns962E444A5D6hamtaromuenchenistto@62.245.150.226...
quote:
> "Dana" <anon@noneya.com> wrote in
> news:114v1aup458nsc5@corp.supernews.com:
>
>
> Wait - is this installation connected to a telephone network, e.g. of one
> of the RBOCs? In this case is could be in conflict with NEC rules and the
> safety requirements from NEBS. This could be an interesting case ...
We are not one of the RBOCs, but we have similar equipment like T1,T3, and
DS0 circuits for voice, data and video, all backhauled from the remote sites
via microwave radio.
Military training range for aircraft is what the equipment supports.
I used to work for cellular companies, and I asked our engineers who are
attempting to implement our circuits and electrical service if they are
familiar with NEBS. Heck I tried to get the company to purchase a copy of
the relevant standards from Telcordia and was turned down.
quote:
>
> Michael
| |
| mroberds@worldnet.att.net 2005-06-17, 11:30 pm |
| Dana <anon@noneya.com> wrote:
quote:
>I have the following situation.
Normally I would send this by email, but your email address doesn't
seem to be good (and, after reading your posts, there is a good reason
for that -- posting through Supernews is also a good idea, given the
situation.)
I am not an electrician or an electrical engineer, just a hobbyist. I
_have_ worked with basic house wiring, and also stacks of batteries (small
by telecom standards -- 144 V, 25 Ah), and the things you are describing
sound at the least wrong and at the most dangerous and scary.
If you are trying to get outside verification that this is an unsafe
installation, it sounds like even Bob from Bob's Electrical Service
could tell you that the generator and power distribution setup isn't
right. The DC distribution stuff will require somebody with that
experience (telecom most likely), but even Bob will be able to tell you
"That ain't right" when you point out the bypassed fuse to him. You'll
have to pay Bob a little extra for coming out to the top of the mountain,
but it will be well worth it.
Unfortunately, given that that you seem to be working for a contractor
for .mil, your co-workers may be correct when they say they don't _have_
to follow any codes or standards. I suspect that even if the National
Electrical Code and friends does not apply, there is some other federal
or military standard that applies. But since you're not building
equipment for combat, it's probably unlikely that anyone would ever check.
I don't know how much of a problem this actually is for you, but if you
do take some pictures, be intelligent. In other words, don't take
pictures of anything that couldn't be ordered by the man in the street
given a stout enough credit card. It sounds like the place you work for
is moderately resistant to doing things right, and if you have the
corner of the wrong radio in a picture, it's a lot easier and cheaper
to revoke your clearance and fire you than it is to fix the problem.
You may well find that once you get to the right level of management,
things get easier. But, you could also find a stone wall all the way
up. Since it does seem to be a government contract, your last option is
always calling your friendly local Senator. You should have another job
lined up before you do this, though.
Good luck!
Matt Roberds
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| Dale Farmer 2005-06-17, 11:30 pm |
|
Dana wrote:
[vbcol=seagreen]
> "Michael" <hamtaro@muenchen-ist-toll.de> wrote in message
> news:Xns962E444A5D6hamtaromuenchenistto@62.245.150.226...
>
> We are not one of the RBOCs, but we have similar equipment like T1,T3, and
> DS0 circuits for voice, data and video, all backhauled from the remote sites
> via microwave radio.
> Military training range for aircraft is what the equipment supports.
> I used to work for cellular companies, and I asked our engineers who are
> attempting to implement our circuits and electrical service if they are
> familiar with NEBS. Heck I tried to get the company to purchase a copy of
> the relevant standards from Telcordia and was turned down.
You are supporting US military systems, then you have to follow DoD
rules and regs, which pretty much require you to follow the NEC and
OSHA rules unless you are in a combat situation. They are required to
follow the relevant military safety standards, which pretty much echo
OSHA and so on. The military is a lot more stringent on supporting
personnel safety than commercial operations are, when you actually
get down to the nitty gritty. They actually follow the rules, once you
point them out to them, in most cases. The managers ( aka, the officers )
will be held criminally liable for accidents caused by their failure to
follow the rules, unlike the civilian world where the company just
gets a fine and an increase in their insurance premium.
The DoD also has an anonymous safety complaint system that may
be useful to you, and the various whistle blower protection laws.
--Dale
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<mroberds@worldnet.att.net> wrote in message
news:X214e.44235$Fy.20783@okepread04...
quote:
> Dana <anon@noneya.com> wrote:
>
> Normally I would send this by email, but your email address doesn't
> seem to be good (and, after reading your posts, there is a good reason
> for that -- posting through Supernews is also a good idea, given the
> situation.)
>
> I am not an electrician or an electrical engineer, just a hobbyist. I
> _have_ worked with basic house wiring, and also stacks of batteries (small
> by telecom standards -- 144 V, 25 Ah), and the things you are describing
> sound at the least wrong and at the most dangerous and scary.
>
> If you are trying to get outside verification that this is an unsafe
> installation, it sounds like even Bob from Bob's Electrical Service
> could tell you that the generator and power distribution setup isn't
> right. The DC distribution stuff will require somebody with that
> experience (telecom most likely), but even Bob will be able to tell you
> "That ain't right" when you point out the bypassed fuse to him. You'll
> have to pay Bob a little extra for coming out to the top of the mountain,
> but it will be well worth it.
>
> Unfortunately, given that that you seem to be working for a contractor
> for .mil, your co-workers may be correct when they say they don't _have_
> to follow any codes or standards. I suspect that even if the National
> Electrical Code and friends does not apply, there is some other federal
> or military standard that applies. But since you're not building
> equipment for combat, it's probably unlikely that anyone would ever check.
>
> I don't know how much of a problem this actually is for you, but if you
> do take some pictures, be intelligent. In other words, don't take
> pictures of anything that couldn't be ordered by the man in the street
> given a stout enough credit card. It sounds like the place you work for
> is moderately resistant to doing things right, and if you have the
> corner of the wrong radio in a picture, it's a lot easier and cheaper
> to revoke your clearance and fire you than it is to fix the problem.
>
> You may well find that once you get to the right level of management,
> things get easier. But, you could also find a stone wall all the way
> up. Since it does seem to be a government contract, your last option is
> always calling your friendly local Senator. You should have another job
> lined up before you do this, though.
>
> Good luck!
>
> Matt Roberds
Every thing you have said is pretty much right on.
As for following code, the military manuals and regs that cover these kinds
of installation also reference the NEC, so I think if some how the military
found out about the cutting of corners and the non standard way that the
electrical service has been installed, as well as simple telecom circuit
installations that have been botched, they may have some questions for the
contractor.
Fighting management just to ensure things are done right the first time,
which by the way would save the contractor money related to man hours
required to fix the problems that have been caused by these installations,
as well as saving money on equipment repair or replacement (especially on
the blade time required for the helicopter trips). But management seems to
not care, even with the waste of money that occurs because of this.
But from my experience with commercial carriers before coming here, this
kind of sup par installations would not be tolerated very long.
quote:
>
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|
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"Dale Farmer" <dale@cybercom.net> wrote in message
news:42509EC0.5150596@cybercom.net...
quote:
>
>
> Dana wrote:
>
all[vbcol=seagreen]
in[vbcol=seagreen]
one[vbcol=seagreen]
the[vbcol=seagreen]
and[vbcol=seagreen]
sites[vbcol=seagreen]
of[vbcol=seagreen]
>
> You are supporting US military systems, then you have to follow DoD
> rules and regs, which pretty much require you to follow the NEC and
> OSHA rules unless you are in a combat situation. They are required to
> follow the relevant military safety standards, which pretty much echo
> OSHA and so on. The military is a lot more stringent on supporting
> personnel safety than commercial operations are, when you actually
> get down to the nitty gritty. They actually follow the rules, once you
> point them out to them, in most cases. The managers ( aka, the officers )
> will be held criminally liable for accidents caused by their failure to
> follow the rules, unlike the civilian world where the company just
> gets a fine and an increase in their insurance premium.
> The DoD also has an anonymous safety complaint system that may
> be useful to you, and the various whistle blower protection laws.
I found that site you were talking about, and have sent in a list of issues
they may want to look at on the range.
I think late last week the company found out about it, because now they are
jumping through hoops.
And are a tad bit upset that someone reported the issues to the IG.
To indicate how wide spread the problems are, the contract has never in the
13 years since the transmission lines have been on the towers conducted any
sweeps on these lines, and for years it has been known that the lines leak
water into the shelters when the ice and snow starts to melt (We are in
Alaska). Needless to say some of these transmission lines more than likely
have defective connectors at the antenna ends, and with the length of time
they have had these problems, the cables are probably in very bad shape from
corrosion.
Some of the shelters are being moved into new shelters this summer, the plan
is to just bend the transmission lines to the direction required to enter
the new building. I reccomended that we sweep the lines and this would be a
great time to replace those that are showing higher loss than is expected.
Of course this was shot down, so I am just waiting to see what happens when
they try to change the direction of the lines on the towers, after they have
been in place for 13 years.
I think I may end up making some jumper cables this summer, and have to suck
up the loss this would entail.
quote:
>
> --Dale
>
>
| |
| mroberds@worldnet.att.net 2005-06-17, 11:30 pm |
| Dana <anon@noneya.com> wrote:
quote:
>As for following code, the military manuals and regs that cover these kinds
>of installation also reference the NEC, so I think if some how the military
>found out about the cutting of corners and the non standard way that the
>electrical service has been installed, as well as simple telecom circuit
>installations that have been botched, they may have some questions for the
>contractor.
That depends on how good a kickback the Congresscritter and/or general
is getting from from the contractor...
quote:
>But management seems to not care, even with the waste of money that occurs
>because of this.
Sounds like a "cost plus" contract. More cost = more profit for the
company.
quote:
>But from my experience with commercial carriers before coming here, this
>kind of sup par installations would not be tolerated very long.
Welcome to the world of government contracting.
Matt Roberds
| |
| Roy Q.T. 2005-06-17, 11:30 pm |
| I've been reading this thread and other than exciting/dangerous and
intriguing., I wish i were there};-)
at first i thought it was just a matter of juggling circuits around.
I'm keeping you in my prayers tonight Dana.
Codes and Regs. is there for a reason, I can't, I refuse to understand
why any Professional or Government out fit would knowingly neglect or
undermine them.
The first thing you need to do is disconnect your DC & Comm systems from
the Electrical System Ground.,(this is covered by the NEC) they should
have their own separate grounding means this should in fact reduce if
not eliminate the signal to noise ratio you've been experiencing....
One good Lighting Suppression System in the Right Place is probably all
you need.
NOTE: any cloak & dagger stuff or Dubiousness revolving around Gov
Electrical Installations ~ you should call the Exo-Squad or AHJ
immediately }:-{) Let them Handle the puppets in & behind the boxes, Oh
! just carry your Ray Gun or Phasor with you at all times until it is
all resolved };-)
Best Wishes;
=AEoy
| |
| Roy Q.T. 2005-06-17, 11:30 pm |
| I also found this: it doesn't cover the exact point for your 3Ph system
but it should come i handy >~~~>
Signal Reference Grid Recommendations
Constructing the Signal Reference Grid
To prevent electrical noise from affecting computers and other equipment
containing solid-state devices, two entirely different and separate
grounding systems are required. First, the power distribution system
must be grounded in accordance with the National Electrical Code (and
all applicable local codes) requirements for safety; and second, the
computer equipment and enclosures must be connected to a signal
reference grid (SRG) system for high frequencies. This high-frequency
protection is in no way related to system grounding. In fact, the
high-frequency reference will work whether or not it is grounded to the
system ground. However, since it consists of exposed, metallic
noncurrent-carrying parts that could accidentally become energized, it
must be grounded as required by the 1999 National Electrical Code,
Section 250-110.
=A0
The intent of the signal reference grid is to establish an equipotential
ground plane where everything connected rises and falls together in the
event of an electrical disturbance, from whatever source. Electronic
equipment is affected when there is a potential difference between
devices. An equipotential grid significantly reduces potential
differences, thus reducing current flow thereby eliminating the adverse
affect on logic circuits. It should be noted that electrical noise of
any frequency cannot be completely eliminated - only reduced. Thus, the
objective of any grounding plane is noise reduction.
=A0
The signal reference grid is constructed using (in order of preference)
flat braided copper cable, flat copper strips, or round multi-strand
copper conductor. Due to the "skin effect" characteristic of
high-frequency signals, flat braided copper cable offers superior
performance. Of equal importance is cable length. High frequency noise
attenuation is dependent on cable impedance which is dependent on cable
length; the shorter the better. Of the available sizes, 1"-wide cable is
preferred but =BE"-wide is acceptable.
=A0
I hope it helps you in solving the specific problem.
Roy ~ E.E.Technician
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