Hall Effect for outlet strips

[David Lesher]

So on the NANOG list, there's a thread on where to find a rack-mount
outlet strip with per-outlet measurement, for bill-back purposes in
a server hotel environment.

The data so far is grim:

{baytech}
I had moderate success with this suggestion. Their technical support said
the only product they had that does this is the 4 outlet RPC5 or RPC6
(ethernet version vs serial version). Unfortunately, it costs $644 each
(lowest price I've found so far) and accomplishes it's individual
monitoring by replicating power in and power out plus an ethernet port 4
times. Still, if it's the only one out there I guess they win (although
at $150 per outlet, ouch, that goes over my $4000 budget for this).

http://www.baytech.net/products/prodlist.php?show=RPC5

And it's not UL-approved.

So I was thinking; is there a Hall-effect package that could
cheaply tell you raw amps at least on each of n outlets?


--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

David Lesher <wb8foz@panix.com> wrote:

So on the NANOG list, there's a thread on where to find a rack-mount
outlet strip with per-outlet measurement, for bill-back purposes in
a server hotel environment. The data so far is grim: [Baytech RPC5/6
4 outlets for $644] And it's not UL-approved.

This may have come up before, but:

Buy a regular outlet strip and n Kill-A-Watt single-plug watthour meters,
about US$35 each. These meters don't have data output, but this can be
somewhat fixed by 1 to n cheap webcams and creating a web page for someone
in the billing department to look at this month's reading, last month's
reading, and doing the math. For more automation, there is a single-plug
watthour meter with serial port, the Watts Up Pro. About US$125 each.

I think some UPSes (APC Smart-UPS?) report the current load, even when
they're not on battery. Maybe you could buy a cheap, small UPS for each
server, and use its built-in monitoring. You're not after the UPS
functionality - that is still provided by the big UPS and generator for
the whole data center.

If the hotel owner can run their own code on the servers, you might be
able to do it by proxy. Temporarily install a watthour meter and note
its reading for the server in each of three states: idle, running all
the disks ('find /'?) only, and running 100% CPU (Seti@Home?) on all
CPUs only. Then use something like MRTG to collect stats from each
machine and compute electrical usage based on the disk and CPU load and
the measured energy consumption.

I've only bought co-lo space, and not sold it, but I wonder: is price so
important and margin so low that the ability to charge a customer less
if they use less electricity is that important?

So I was thinking; is there a Hall-effect package that could
cheaply tell you raw amps at least on each of n outlets?

Digi-Key sells a Melexis MLX90215 Hall-effect IC that looks like it might
work for $11/1 and $7/50. There is a page on the data sheet about using
it for current sensing. I don't know anything about it other than it
exists.

Matt Roberds

 

[John Larkin]

On Wed, 10 Aug 2005 01:42:09 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

So on the NANOG list, there's a thread on where to find a rack-mount
outlet strip with per-outlet measurement, for bill-back purposes in
a server hotel environment.

The data so far is grim:


{baytech}
I had moderate success with this suggestion. Their technical support said
the only product they had that does this is the 4 outlet RPC5 or RPC6
(ethernet version vs serial version). Unfortunately, it costs $644 each
(lowest price I've found so far) and accomplishes it's individual
monitoring by replicating power in and power out plus an ethernet port 4
times. Still, if it's the only one out there I guess they win (although
at $150 per outlet, ouch, that goes over my $4000 budget for this).

http://www.baytech.net/products/prodlist.php?show=RPC5

And it's not UL-approved.

So I was thinking; is there a Hall-effect package that could
cheaply tell you raw amps at least on each of n outlets?

A small current transformer+burden resistor will cost a couple of
dollars per load, with isolation. Run ton of these into a cheap 32 or
64-channel ADC card, from Measurement Computing or somebody. Then just
hack a little code to sample and process the current signals. One
cheap PC could handle a hundred loads or so. Not much more work would
get you true power, not just amps.

John

 

[Ban]

David Lesher wrote:

So on the NANOG list, there's a thread on where to find a rack-mount
outlet strip with per-outlet measurement, for bill-back purposes in
a server hotel environment.

The data so far is grim:


{baytech}
I had moderate success with this suggestion. Their technical
support said the only product they had that does this is the 4
outlet RPC5 or RPC6 (ethernet version vs serial version).
Unfortunately, it costs $644 each (lowest price I've found so far)
and accomplishes it's individual monitoring by replicating power in
and power out plus an ethernet port 4 times. Still, if it's the
only one out there I guess they win (although at $150 per outlet,
ouch, that goes over my $4000 budget for this).

http://www.baytech.net/products/prodlist.php?show=RPC5

And it's not UL-approved.

So I was thinking; is there a Hall-effect package that could
cheaply tell you raw amps at least on each of n outlets?

That is not how it works, you have to sample the momentary values and
multiply them, process, then embed an ethernet controller etc. Not a trivial
task. I also would use just current transformers, hall sensors (Lem makes
them) are even more expensive and require extensive analog conditioning.
So with a PIC and a CT per outlet you could probably come along. But you
will not have the skills, if you don't know about phase angle. Go buy that
ready made outlet!

--
ciao Ban
Bordighera, Italy

 

[John Larkin]

On Wed, 10 Aug 2005 04:43:13 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> writes:

And it's not UL-approved.

So I was thinking; is there a Hall-effect package that could
cheaply tell you raw amps at least on each of n outlets?

A small current transformer+burden resistor will cost a couple of
dollars per load, with isolation.

UL-satifying isolation? I suspect not...

Certainly with insulation type and thickness compliant with UL rules.
Maybe even listed, for a couple more bucks in quantity. I've bought
100 amp metering-quality CTs from Crompton, UL listed, for about $8.

John

 

[David Lesher]

mroberds@worldnet.att.net writes:

This may have come up before, but:

Buy a regular outlet strip and n Kill-A-Watt single-plug watthour meters,
about US$35 each. These meters don't have data output, but this can be
.....
watthour meter with serial port, the Watts Up Pro. About US$125 each.

So skipping the ugly kludge; you're talking $125/port.

I think some UPSes (APC Smart-UPS?) report the current load, even when
they're not on battery. Maybe you could buy a cheap, small UPS for each
server, and use its built-in monitoring. You're not after the UPS
functionality - that is still provided by the big UPS and generator for
the whole data center.

Look; space is money. The wasted space of the UPS's is just that...

If the hotel owner can run their own code on the servers, you might be
able to do it by proxy. Temporarily install a watthour meter and note

Does not fit the requirements.. They want data, not SWAGs...

I've only bought co-lo space, and not sold it, but I wonder: is price so
important and margin so low that the ability to charge a customer less
if they use less electricity is that important?

When you consider each watt bites you twice -- once for the box, again
for the HVAC to remove the heat...

--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[David Lesher]

John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> writes:

And it's not UL-approved.

So I was thinking; is there a Hall-effect package that could
cheaply tell you raw amps at least on each of n outlets?

A small current transformer+burden resistor will cost a couple of
dollars per load, with isolation.

UL-satifying isolation? I suspect not...
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[Ban]

David Lesher wrote:

mroberds@worldnet.att.net writes:

This may have come up before, but:

Buy a regular outlet strip and n Kill-A-Watt single-plug watthour
meters, about US$35 each. These meters don't have data output, but
this can be .... watthour meter with serial port, the Watts Up Pro.
About US$125 each.

So skipping the ugly kludge; you're talking $125/port.

I think some UPSes (APC Smart-UPS?) report the current load, even
when they're not on battery. Maybe you could buy a cheap, small UPS
for each server, and use its built-in monitoring. You're not after
the UPS functionality - that is still provided by the big UPS and
generator for the whole data center.

Look; space is money. The wasted space of the UPS's is just that...

If the hotel owner can run their own code on the servers, you might
be able to do it by proxy. Temporarily install a watthour meter and
note

Does not fit the requirements.. They want data, not SWAGs...

I've only bought co-lo space, and not sold it, but I wonder: is
price so important and margin so low that the ability to charge a
customer less if they use less electricity is that important?

When you consider each watt bites you twice -- once for the box, again
for the HVAC to remove the heat...

Hey you talk like a computer tech. Have you ever ask yourself, what should
this expensive investment be good for? The guest will only hook up his
laptop or his cellphone charger. One hot shower or 10 min. of hairdryer will
cost more than 10h of all that equipment. And what can the hotel owner
charge? 1$ per kWh? Then this investment will never pay off.
--
ciao Ban
Bordighera, Italy

 

[legg]

On Wed, 10 Aug 2005 01:42:09 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

So on the NANOG list, there's a thread on where to find a rack-mount
outlet strip with per-outlet measurement, for bill-back purposes in
a server hotel environment.



So I was thinking; is there a Hall-effect package that could
cheaply tell you raw amps at least on each of n outlets?

I should have thought that a simple hook-up fee would more than cover
any energy usage that was physically possible/probable, if all you
want is another frigging item line on the hotel user's bill.

RL

 

[Richard H.]

David Lesher wrote:

So on the NANOG list, there's a thread on where to find a rack-mount
outlet strip with per-outlet measurement, for bill-back purposes in
a server hotel environment.

This won't appease the techies on NANOG, but this problem doesn't scream
for a technical solution.

Servers shouldn't vary their consumption much, so why meter? Set the
billing rate based on either the rating plate of the power supply, or a
one-time reading of the server before it's installed. Both are easy
one-time checks, and they're defined values that both parties can plan
around. (And yes, they both have weaknesses that could be exploited,
but significant enough to need a much more complex solution?)

The facility needs this data to size the circuit anyway, and all the
facilities I know charge by the circuit anyway to recover power and
cooling costs (widely varying, but ballpark $200/20A per month).

Richard

 

[David Lesher]

"Ban" <bansuri@web.de> writes:

When you consider each watt bites you twice -- once for the box, again
for the HVAC to remove the heat...

Hey you talk like a computer tech. Have you ever ask yourself, what should
this expensive investment be good for? The guest will only hook up his
laptop or his cellphone charger. One hot shower or 10 min. of hairdryer will
cost more than 10h of all that equipment. And what can the hotel owner
charge? 1$ per kWh? Then this investment will never pay off.

Sir:

I fear you misunderstand the basic issue.

A "server hotel" is a term for a dedicated facility that houses
servers, hundreds of servers, and nothing else but same. There
are no hot showers, hairdryers, or even windows. [1] And the only
food MIGHT be a junk food vending machine in the office area,
if there even is one. {Most are unmanned...} If there's someone
there at night, they are most likely frantically trying to get
their customer's server back on-line.

And depending on the lease terms, the landlord does ndeed charge
back for every KWH used. The question was and is how to easily log
same.

[1] Well...If there's a large battery room + UPS, there may be a
OSHA-required cold shower..

--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[legg]

On Wed, 10 Aug 2005 23:46:23 +0000 (UTC), David Lesher
<wb8foz@panix.com> wrote:

I fear you misunderstand the basic issue.

A "server hotel" is a term for a dedicated facility that houses
servers, hundreds of servers, and nothing else but same. There
are no hot showers, hairdryers, or even windows.
snip.....
And depending on the lease terms, the landlord does ndeed charge
back for every KWH used. The question was and is how to easily log
same.

I guess he's not the only one mislead by your use of the term "server
hotel".

Perhaps you might consider a portable 'mousetrap'-type monitoring of
slow-peak energy usage - as this is what affects your hardware sizing
and infrastructure costs, rather than actual consumption. The two
readings are likely corelated.

A self-powered CT with a long time constant average current
measurement, a (latching?) presetable threshold and indicators of
in/out of range. The user pays for the in-range threshold setting
applied, with out-of range penalties. Very manual monitoring and all
hardware - I know - but low-tech and also potentially log-able at
'one' link per monitor. How the info is handled.......

The usual problem with VAR relationships occur, when current is the
unit of measure, but there would always be bitching, anyways.

Alternately, simply charge by the input power label rating of
plugged-in equipment. A calculation of total plant usage vs total
label ratings would give a ballpark cost per label-watt-hour in any
billing period. Utility rates are a variable. Accuracy is probably
unimportant - you just need an administrative procedure that produces
cashflow, supposedly for energy delivery cost compensation.

RL

 

David Lesher <wb8foz@panix.com> wrote:

watthour meter with serial port, the Watts Up Pro. About US$125 each.

So skipping the ugly kludge; you're talking $125/port.

Yep. Specs stated or implied in your first post were: rack-mount outlet
strip, per-outlet power measurement, UL approved, price to beat is
$161/port. In the absence of other data, I figured kludginess vs.
~$80/port savings was a good trade-off.

Look; space is money. The wasted space of the UPS's is just that...

The APC 350 VA "fat power strip" UPSes can be had for $30 each.
$95/port vs. space.

If the hotel owner can run their own code on the servers, you might be
able to do it by proxy.

Does not fit the requirements.. They want data, not SWAGs...

But they don't want to pay very much for the data.

I wonder: is price so important and margin so low that the ability to
charge a customer less if they use less electricity is that important?

When you consider each watt bites you twice -- once for the box, again
for the HVAC to remove the heat...

And, AFAIK, this is normally reflected in the pricing of the rack space
- when you pay for a 15A or 20A circuit, you're paying for the electricity
to bring the heat in and the cooling to take it back out.

Again, it would be really interesting to see the business case for this.

Matt Roberds

 

[Ban]

David Lesher wrote:

"Ban" <bansuri@web.de> writes:

When you consider each watt bites you twice -- once for the box,
again for the HVAC to remove the heat...

Hey you talk like a computer tech. Have you ever ask yourself, what
should this expensive investment be good for? The guest will only
hook up his laptop or his cellphone charger. One hot shower or 10
min. of hairdryer will cost more than 10h of all that equipment. And
what can the hotel owner charge? 1$ per kWh? Then this investment
will never pay off.

Sir:

I fear you misunderstand the basic issue.

A "server hotel" is a term for a dedicated facility that houses
servers, hundreds of servers, and nothing else but same. There
are no hot showers, hairdryers, or even windows. [1] And the only
food MIGHT be a junk food vending machine in the office area,
if there even is one. {Most are unmanned...} If there's someone
there at night, they are most likely frantically trying to get
their customer's server back on-line.

And depending on the lease terms, the landlord does ndeed charge
back for every KWH used. The question was and is how to easily log
same.

[1] Well...If there's a large battery room + UPS, there may be a
OSHA-required cold shower..

So you *are* a computer tech. I'm not that familiar with IT slang, only know
server farms. THX for the explanation. BTW it's kWh not KWH.
A pity you are not familiar with circuit design, because in your case where
hundreds of monitors are needed, it might be useful to develop a small
gadget with a PIC that does accumulate the consumed kWh and reads them out
via ethernet. And such a gadget will even sell to other similar businesses,
so there might be a nice-market for the power/work monitor. I would guess
the hardware costs below 25$ for moderate runs.
--
ciao Ban
Bordighera, Italy

 

[Keith Williams]

In article <bxBKe.63744$fm.4205927@news4.tin.it>, bansuri@web.de
says...

David Lesher wrote:
"Ban" <bansuri@web.de> writes:

When you consider each watt bites you twice -- once for the box,
again for the HVAC to remove the heat...

Hey you talk like a computer tech. Have you ever ask yourself, what
should this expensive investment be good for? The guest will only
hook up his laptop or his cellphone charger. One hot shower or 10
min. of hairdryer will cost more than 10h of all that equipment. And
what can the hotel owner charge? 1$ per kWh? Then this investment
will never pay off.

Sir:

I fear you misunderstand the basic issue.

A "server hotel" is a term for a dedicated facility that houses
servers, hundreds of servers, and nothing else but same. There
are no hot showers, hairdryers, or even windows. [1] And the only
food MIGHT be a junk food vending machine in the office area,
if there even is one. {Most are unmanned...} If there's someone
there at night, they are most likely frantically trying to get
their customer's server back on-line.

And depending on the lease terms, the landlord does ndeed charge
back for every KWH used. The question was and is how to easily log
same.

[1] Well...If there's a large battery room + UPS, there may be a
OSHA-required cold shower..

So you *are* a computer tech. I'm not that familiar with IT slang, only know
server farms. THX for the explanation. BTW it's kWh not KWH.
A pity you are not familiar with circuit design, because in your case where
hundreds of monitors are needed, it might be useful to develop a small
gadget with a PIC that does accumulate the consumed kWh and reads them out
via ethernet. And such a gadget will even sell to other similar businesses,
so there might be a nice-market for the power/work monitor. I would guess
the hardware costs below 25$ for moderate runs.

I bought a W/kWh/VA/current/voltage/PF meter for $32:

http://www.newegg.com/OldVersion/app/ViewProductDesc.asp?description=
99-887-001&depa=0

(sorry for the wrap)

--
Keith

 

[David Lesher]

"Ban" <bansuri@web.de> writes:

Well...If there's a large battery room + UPS, there may be a
OSHA-required cold shower..

So you *are* a computer tech. I'm not that familiar with IT slang, only know
server farms. THX for the explanation. BTW it's kWh not KWH.

Not at all; I'm a EE. I just do not now do the kind of design/build
work that many others here do. (I've done some such work in decades
past....)

A pity you are not familiar with circuit design, because in your case where
hundreds of monitors are needed, it might be useful to develop a small
gadget with a PIC that does accumulate the consumed kWh and reads them out
via ethernet. And such a gadget will even sell to other similar businesses,
so there might be a nice-market for the power/work monitor. I would guess
the hardware costs below 25$ for moderate runs.

Well, one basic rule is "don't reinvent the wheel..." so I asked
here to see what, if anything, was available already. And if you
think you can deliver such a gadget, UL/etc certified, for $25/port;
I can point you to lots of potential customers.
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[David Lesher]

Keith Williams <krw@att.bizzzz> writes:

http://www.newegg.com/OldVersion/app/ViewProductDesc.asp?description=
99-887-001&depa=0

That looks like a reboxed "Kill-o-Watt" meter; they are nifty -- I
have one on my fridge right now. But it lacks a Ethernet port....

--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

 

[keith]

On Thu, 11 Aug 2005 22:58:48 +0000, David Lesher wrote:

Keith Williams <krw@att.bizzzz> writes:

http://www.newegg.com/OldVersion/app/ViewProductDesc.asp?description=
99-887-001&depa=0

That looks like a reboxed "Kill-o-Watt" meter; they are nifty

I bought it because it was nifty and to measre the power consumptioni of
my computer gear. So far all I've found is that my bedroom AC draws
400W with the compressor on, with a .9 PF. No time to play.

I have one on my fridge right now. But it lacks a Ethernet port....

Oops. Forgot that requirement. How about X10 security cameras, with... ;-)

--
Keith

 

[keith]

On Sat, 13 Aug 2005 02:39:22 +0000, David Lesher wrote:

So I have one on my fridge. The compressor is off, so the only draw
is maybe the defrost timer?

I open the door, the light goes on, and the PF gets *worse*... WHAT?
Then, later, I try again, and the PF improves to near unity.

You have too much time on your hands. ;-)

Still pondering...

Some things have no answers. I have to move the 'fridge, range, and
island out to the front porch tomorrow (good thing we have no crappy HOA),
so maybe I'll have time to play with it. ;-)

--
Keith

 

[David Lesher]

So I have one on my fridge. The compressor is off, so the only draw
is maybe the defrost timer?

I open the door, the light goes on, and the PF gets *worse*... WHAT?
Then, later, I try again, and the PF improves to near unity.

Still pondering...



--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433