Re: [time-nuts] Oscilloquartz BVA has been sold. Thank you all who expressed an interest.
Can't I just use a high quality APC backup power system
like we use to power racks of gear in our Telco and compute closets?
Very few UPS's are good at long-run applications, they are typically built to
run a heavy load for minutes, not a tiny load for hours or even days on end.
That matches my expectations, but somebody might expect their telco gear to
stay up longer than the few minutes it takes to cleanly shut down a computer.
Is there a branch of UPS gear aimed at telco rather than computers? That is
good efficiency at low power and long time rather than high power for short
time.
Does all telco gear that is expected to run off UPS take 48V?
Is there a market in small 48V supplies with UPS option for the telco market?
You would have to build a 48V to 24V converter rather than the whole thing.
You can probably get a brick for that.
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On Sat, Sep 26, 2020 at 7:36 AM Hal Murray hmurray@megapathdsl.net wrote:
Can't I just use a high quality APC backup power system
like we use to power racks of gear in our Telco and compute closets?
Very few UPS's are good at long-run applications, they are typically
built to
run a heavy load for minutes, not a tiny load for hours or even days on
end.
That matches my expectations, but somebody might expect their telco gear
to
stay up longer than the few minutes it takes to cleanly shut down a
computer.
Is there a branch of UPS gear aimed at telco rather than computers? That
is
good efficiency at low power and long time rather than high power for
short
time.
Does all telco gear that is expected to run off UPS take 48V?
48VDC is common. Historically facilities that provide highly available AC
usually do so via generator. The UPSes just need to last long enough for
the generators to start.
Keep in mind that during a long run HVAC needs to be supported too.
Hal Murray writes:
Very few UPS's are good at long-run applications, they are typically built to
run a heavy load for minutes, not a tiny load for hours or even days on end.
That matches my expectations, but somebody might expect their telco gear to
stay up longer than the few minutes it takes to cleanly shut down a computer.
Real Telco gear runs from -48VDC fed from, literally, tons of lead-acid batteries.
Google "telco battery room" pictures if you dont belive me.
Incidentally, the best batteries for this kind of application are literally
called "circular telco batteries", and almost all of them are still in use,
some of them pushing 50 years now:
https://archive.org/details/bstj49-7-1253/page/n23/mode/2up
Does all telco gear that is expected to run off UPS take 48V?
In the sense that telcos rarely buy anything but -48VDC kit: Yes.
Is there a market in small 48V supplies with UPS option for the telco market?
You would have to build a 48V to 24V converter rather than the whole thing.
You can probably get a brick for that.
All of 12, 24 and 48VDC are commonly used, and IMO most timing kit is 24VDC.
24VDC is also popular in industrial control settings, for instance:
https://www.pulspower.com/products/supplementary-units/dc-ups-and-buffer-modules/
It's expensive and good, but these days almost all of it is switch-mode.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
A few decades ago I worked with some quite large Telecom gear that ran from 208 volt AC. The equipment had its own internal 48 volt supplies and short term battery back up system (basically so the redundant CPU units could gracefully shut down in the event of a power failure.) The manufacturer also sold similar systems that ran from customer supplied 48 volts but many enterprise customers who already had large UPS systems and back up generators preferred the versions that ran from 208 volt AC.
Some smaller office phone systems back in the early 1990's also featured large external battery packs to get multi hour run times. The vendors would typically send technicians out to peridoically check the battery systems. The few that I was able to examine were typically made up from 2 volt sealed lead acid cells. The used cells used to be some what available to hobbyists as the tended to get replaced before they failed.
Yes some large UPS systems don't work very well at supplying low levels of power for long the periods. During a multi hour maintenance shut down at work a few decades ago we had one device that we hoped to keep running (essentially a small digital voice play back unit that played phone system messages, ie. "The number you have reached is not in service.") It drew well under 100 watts and was the only load at the time for a large UPS system with multiple battery banks which stopped running after a few hours and I had to re record the messages. None of us were very surprised.
Mark Spencer
mark@alignedsolutions.com
604 762 4099
On Sep 26, 2020, at 12:33 AM, Hal Murray hmurray@megapathdsl.net wrote:
Can't I just use a high quality APC backup power system
like we use to power racks of gear in our Telco and compute closets?
Very few UPS's are good at long-run applications, they are typically built to
run a heavy load for minutes, not a tiny load for hours or even days on end.
That matches my expectations, but somebody might expect their telco gear to
stay up longer than the few minutes it takes to cleanly shut down a computer.
Is there a branch of UPS gear aimed at telco rather than computers? That is
good efficiency at low power and long time rather than high power for short
time.
Does all telco gear that is expected to run off UPS take 48V?
Is there a market in small 48V supplies with UPS option for the telco market?
You would have to build a 48V to 24V converter rather than the whole thing.
You can probably get a brick for that.
--
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Where I work on a smaller isolated network we have an APC that takes up one
full rack. Most of the rack is modular batteries that are 6 batteries in
19" x 4U high... A bunch of rows of these in one rack with a few units that
are the control and monitoring system. That one rack can support 6 rows of
racks of equipment 5 19" racks wide. That one APC rack can run all the
computers, NAS, blade centers, etc. for about an hour. Some of the racks
are 110AC some are 208AC depending on circuit it's on. It seems like I
could get one of the bottom of the rack APC units (really heavy) that are I
think 4U high. The batteries usually last longer depending on the load.
Our big unit tells you right on the front how long in minutes it will last
based on the current load.
Are you saying if the load is small it'll still run out pretty quickly? I
was thinking just plug a few things in:
BVA power supply, HP 105B, some GPS/GNSSDO's and the HP5065A. I don't even
think there's any reason to plug a Cesium into it. If a Cesium in storage
mode is off for a while who cares right? I have a few older Efratom Rb too
FRK-L and a couple M-100. Would those benefit from staying on? I have a
few newer Rb but they would just run until Rubidium ran out right like SRS
PRS-10 and L-Pro's? I've heard the older Rb can be ran all the time
because they have much more Rubidium in them. Up to this point I usually
run them for a couple days to stabilize them before using them. I'm not
100% sure if leaving them on all the time is of much benefit? I know Ed
told me he leaves his 5065 on all the time so I'm planning the same thing
right now also mines recently put back together and as it runs it's getting
better and better right now.
I really like these older Rb units with larger physics packages.
Best Regards,
Bill
On Sat, Sep 26, 2020, 9:16 AM Mark Spencer mark@alignedsolutions.com
wrote:
A few decades ago I worked with some quite large Telecom gear that ran
from 208 volt AC. The equipment had its own internal 48 volt supplies
and short term battery back up system (basically so the redundant CPU units
could gracefully shut down in the event of a power failure.) The
manufacturer also sold similar systems that ran from customer supplied 48
volts but many enterprise customers who already had large UPS systems and
back up generators preferred the versions that ran from 208 volt AC.
Some smaller office phone systems back in the early 1990's also featured
large external battery packs to get multi hour run times. The vendors
would typically send technicians out to peridoically check the battery
systems. The few that I was able to examine were typically made up from 2
volt sealed lead acid cells. The used cells used to be some what
available to hobbyists as the tended to get replaced before they failed.
Yes some large UPS systems don't work very well at supplying low levels of
power for long the periods. During a multi hour maintenance shut down at
work a few decades ago we had one device that we hoped to keep running
(essentially a small digital voice play back unit that played phone system
messages, ie. "The number you have reached is not in service.") It drew
well under 100 watts and was the only load at the time for a large UPS
system with multiple battery banks which stopped running after a few hours
and I had to re record the messages. None of us were very surprised.
Mark Spencer
mark@alignedsolutions.com
604 762 4099
On Sep 26, 2020, at 12:33 AM, Hal Murray hmurray@megapathdsl.net
wrote:
Can't I just use a high quality APC backup power system
like we use to power racks of gear in our Telco and compute closets?
Very few UPS's are good at long-run applications, they are typically
built to
run a heavy load for minutes, not a tiny load for hours or even days on
end.
That matches my expectations, but somebody might expect their telco gear
to
stay up longer than the few minutes it takes to cleanly shut down a
computer.
Is there a branch of UPS gear aimed at telco rather than computers?
That is
good efficiency at low power and long time rather than high power for
short
time.
Does all telco gear that is expected to run off UPS take 48V?
Is there a market in small 48V supplies with UPS option for the telco
market?
You would have to build a 48V to 24V converter rather than the whole
thing.
You can probably get a brick for that.
--
These are my opinions. I hate spam.
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You want a substantial UPS go to Victron Energy and get a charger Inverter Multi Plus and add a battery I have done it. Bert Kehren In a message dated 9/26/2020 12:16:16 PM Eastern Standard Time, mark@alignedsolutions.com writes:
A few decades ago I worked with some quite large Telecom gear that ran from 208 volt AC. The equipment had its own internal 48 volt supplies and short term battery back up system (basically so the redundant CPU units could gracefully shut down in the event of a power failure.) The manufacturer also sold similar systems that ran from customer supplied 48 volts but many enterprise customers who already had large UPS systems and back up generators preferred the versions that ran from 208 volt AC.
Some smaller office phone systems back in the early 1990's also featured large external battery packs to get multi hour run times. The vendors would typically send technicians out to peridoically check the battery systems. The few that I was able to examine were typically made up from 2 volt sealed lead acid cells. The used cells used to be some what available to hobbyists as the tended to get replaced before they failed.
Yes some large UPS systems don't work very well at supplying low levels of power for long the periods. During a multi hour maintenance shut down at work a few decades ago we had one device that we hoped to keep running (essentially a small digital voice play back unit that played phone system messages, ie. "The number you have reached is not in service.") It drew well under 100 watts and was the only load at the time for a large UPS system with multiple battery banks which stopped running after a few hours and I had to re record the messages. None of us were very surprised.
Mark Spencer
mark@alignedsolutions.com
604 762 4099
On Sep 26, 2020, at 12:33 AM, Hal Murray hmurray@megapathdsl.net wrote:
Can't I just use a high quality APC backup power system
like we use to power racks of gear in our Telco and compute closets?
Very few UPS's are good at long-run applications, they are typically built to
run a heavy load for minutes, not a tiny load for hours or even days on end.
That matches my expectations, but somebody might expect their telco gear to
stay up longer than the few minutes it takes to cleanly shut down a computer.
Is there a branch of UPS gear aimed at telco rather than computers? That is
good efficiency at low power and long time rather than high power for short
time.
Does all telco gear that is expected to run off UPS take 48V?
Is there a market in small 48V supplies with UPS option for the telco market?
You would have to build a 48V to 24V converter rather than the whole thing.
You can probably get a brick for that.
--
These are my opinions. I hate spam.
time-nuts mailing list -- time-nuts@lists.febo.com
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Bill Notfaded writes:
Are you saying if the load is small it'll still run out pretty quickly?
Yes.
The constant loss of the inverter-stage will be nothing compared
to the full design load, but will totally swamp your light load.
This is why UPS vendors only publish hold-up times for full load.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Hi,
On 2020-09-27 09:02, Poul-Henning Kamp wrote:
Bill Notfaded writes:
Are you saying if the load is small it'll still run out pretty quickly?
Yes.
The constant loss of the inverter-stage will be nothing compared
to the full design load, but will totally swamp your light load.
This is why UPS vendors only publish hold-up times for full load.
Which is why it is a good idea to run the load directly off the
batteries. In telecom, that is -48 VDC (check out the ETSI EN 300 132-2
spec) but there is also one for modern switch-mode supplies for more
IT-infrastructure which is feeding the 230 VAC side the DC it achieves
after rectifier (ETSI EN 300 132-3 spec), but that has not taken off as
far as I know. Both avoids the inverter part. Running straight of the
batteries for 24 VDC matches many of our devices. For instance, all the
atomic clocks and many OCXOs I have essentially run off 24 VDC, so that
will be my focus.
The voltage range for the -48 VDC is really -40 VDC to -60,5 VDC to
match the out of charge to charging voltages of normal lead-acid batteries.
Sure, the 24 V or 48 V may not fit the needs of applications, but you
can usually find DC/DC converters that can be decent enough loss-wise as
they do switched mode drop-regulation. Choosing wisely amongst those,
you can get better losses than a large supply which runs in a
non-optimal mode.
Cheers,
Magnus
Yes running being able to run at least some of my OCXO's from a DC battery system is my desired state of affairs for my home time lab. It is nice to have two devices that have been running for a decade.
Anyways thanks all for the comments about various ways to power my BVA and the trip down memory lane re large UPS systems, Telecom battery plants etc.
It will be nice to have the BVA powered from the a DC battery system. I will be curious to see how the BVA performs after being powered up for at least a year. Currently after running for a month or so it seems to often outperform the other OCXO's that have been running for a decade or so. Between occasional power outages that exceed typical UPS run times and the need to change batteries on occasion in the consumer grade UPS systems I use in my home time lab, getting multi year un interrupted run times without using a DC battery system to power devices during AC power outages seems unlikely for me.
Mark Spencer
mark@alignedsolutions.com
604 762 4099
On Sep 27, 2020, at 4:06 AM, Magnus Danielson magnus@rubidium.se wrote:
Hi,
On 2020-09-27 09:02, Poul-Henning Kamp wrote:
Bill Notfaded writes:
Are you saying if the load is small it'll still run out pretty quickly?
Yes.
The constant loss of the inverter-stage will be nothing compared
to the full design load, but will totally swamp your light load.
This is why UPS vendors only publish hold-up times for full load.
Which is why it is a good idea to run the load directly off the
batteries. In telecom, that is -48 VDC (check out the ETSI EN 300 132-2
spec) but there is also one for modern switch-mode supplies for more
IT-infrastructure which is feeding the 230 VAC side the DC it achieves
after rectifier (ETSI EN 300 132-3 spec), but that has not taken off as
far as I know. Both avoids the inverter part. Running straight of the
batteries for 24 VDC matches many of our devices. For instance, all the
atomic clocks and many OCXOs I have essentially run off 24 VDC, so that
will be my focus.
The voltage range for the -48 VDC is really -40 VDC to -60,5 VDC to
match the out of charge to charging voltages of normal lead-acid batteries.
Sure, the 24 V or 48 V may not fit the needs of applications, but you
can usually find DC/DC converters that can be decent enough loss-wise as
they do switched mode drop-regulation. Choosing wisely amongst those,
you can get better losses than a large supply which runs in a
non-optimal mode.
Cheers,
Magnus
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