Re: [time-nuts] The home time-lab
So, since I need to power the 5370 (preferably both) I'm looking at a deep cycle battery, a charger, and an inverter? At this point in the process, a power line monitor is looking like a good solution. At least it would tell me to ignore the test results.
Bob
-----------------------------------------------------------------------------------
GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
From: Hal Murray <hmurray@megapathdsl.net>
To: Bob Stewart bob@evoria.net; Discussion of precise time and frequency measurement time-nuts@febo.com
Cc: hmurray@megapathdsl.net
Sent: Thursday, July 7, 2016 8:43 PM
Subject: Re: [time-nuts] The home time-lab
bob@evoria.net said:
So, what to do? I've been looking at UPS devices, and I don't even
understand enough to waste my money on a bad one.
A UPS has 2 major properties. One is the amount of power it can put out.
The other is the battery size which translates into how long it will last.
The low cost market is for a unit that will last long enough to let a PC and
friends shut down cleanly. The battery isn't very big. It will cover
typical blink-the-lights glitches. Beyond that, the time is measured in
minutes rather than hours.
--
These are my opinions. I hate spam.
Some UPSes like my old Powerware 9120 monitor the AC line condition
for various things and keep a log but I do not know if that would be
sufficient for what you have in mind.
On Fri, 8 Jul 2016 01:54:58 +0000 (UTC), you wrote:
So, since I need to power the 5370 (preferably both) I'm looking at a deep cycle battery, a charger, and an inverter? At this point in the process, a power line monitor is looking like a good solution. At least it would tell me to ignore the test results.
Bob
On Thu, Jul 7, 2016 at 6:54 PM, Bob Stewart bob@evoria.net wrote:
So, since I need to power the 5370 (preferably both) I'm looking at a deep cycle battery, a charger, and an inverter? At this point in the process, a power line monitor is looking like a good solution. At least it would tell me to ignore the test results.
But then you may find that you can NEVER finish a test. The AC line
is typically full of transients.
I've never thought UPS were a good idea for anything but a computer
that needs to shut down gracefully. For your use you need something
that cleans up the AC mains power. The best ones have a ferroresonant
transformer inside and will hand those few millisecond glitches.
--
Chris Albertson
Redondo Beach, California
But then you may find that you can NEVER finish a test. The AC line
is typically full of transients.
I've never thought UPS were a good idea for anything but a computer
that needs to shut down gracefully. For your use you need something
that cleans up the AC mains power. The best ones have a ferroresonant
transformer inside and will hand those few millisecond glitches.
Chris Albertson
Redondo Beach, California
Chris,
Do you mean like these:
http://www.aelgroup.co.uk/products/agt.php
I have an old 75W unit somewhere....
Cheers,
David
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
Twitter: @gm8arv
Chris wrote:
I've never thought UPS were a good idea for anything but a computer
that needs to shut down gracefully. For your use you need something
that cleans up the AC mains power.
A proper "online" (or "double conversion") UPS does just that. It
always provides cleanly-generated sine-wave power from a DC-AC
converter. Most will even deliver crystal-controlled power (i.e.,
non-synchronous with the AC line) in several frequency increments, if
you desire, as well as a choice of regulated output voltages. (For
obvious reasons, they are usually operated synchronously.)
They are much more effective than ferroresonant supplies at removing
glitches from the mains supply.
You must be referring to "offline" backup supplies.
Best regards,
Charles
Hi
If you go back far enough in time …. there is another alternative:
Big rectifier bank, turning AC into DC, often off of multiple phases or sources.
Big DC motor running into a fairly large flywheel.
AC generator (or in some cases DC generators) running off of the shaft
A tuning fork (yes state of the art timing) based control on the AC output frequency
A saturated reactor control loop on the generator side, same thing on the motor side.
Wonderfull stuff. State of the art UPS for your shipboard computer in 1962. Ear muffs anyone?
Bob
On Jul 25, 2016, at 8:39 AM, Charles Steinmetz csteinmetz@yandex.com wrote:
Chris wrote:
I've never thought UPS were a good idea for anything but a computer
that needs to shut down gracefully. For your use you need something
that cleans up the AC mains power.
A proper "online" (or "double conversion") UPS does just that. It always provides cleanly-generated sine-wave power from a DC-AC converter. Most will even deliver crystal-controlled power (i.e., non-synchronous with the AC line) in several frequency increments, if you desire, as well as a choice of regulated output voltages. (For obvious reasons, they are usually operated synchronously.)
They are much more effective than ferroresonant supplies at removing glitches from the mains supply.
You must be referring to "offline" backup supplies.
Best regards,
Charles
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Charles is correct and most data centers and metrology laboratories operate from power produced by large versions of these systems i.e. From 50KW to megawatts generally backed by one or more generators to carry facility when utility power is not available
Content by Scott
Typos by Siri
On Jul 25, 2016, at 8:39 AM, Charles Steinmetz csteinmetz@yandex.com wrote:
Chris wrote:
I've never thought UPS were a good idea for anything but a computer
that needs to shut down gracefully. For your use you need something
that cleans up the AC mains power.
A proper "online" (or "double conversion") UPS does just that. It always provides cleanly-generated sine-wave power from a DC-AC converter. Most will even deliver crystal-controlled power (i.e., non-synchronous with the AC line) in several frequency increments, if you desire, as well as a choice of regulated output voltages. (For obvious reasons, they are usually operated synchronously.)
They are much more effective than ferroresonant supplies at removing glitches from the mains supply.
You must be referring to "offline" backup supplies.
Best regards,
Charles
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Yes, "ferroresonant" is also called CVT. Typically rather than buying
just the transformer you buy a box that has one in it but also some
other components to clip spikes (some MOVs) and and LC low pass
filter. I know it seems a saturated core might produce a non-sine
wave but current CVTs have very low distortion.
The other option is an on-line UPS, one that always runs off the
battery. These are expensive if you need a good sine wave output.
The UPS has an output stage not unlike an audio amplifier. Not nearly
as efficient as MOSFET switches. (question: I'd guess that modern
versions would be designed with class-D output stages and have decent
power efficiency??)
The best solution is what the phone companies did. The telco style
equipment, like computers and such runs off 48VDC. and batteries are
connected in parallel from a "battery room". If designing your own
GPSDO, it should be built to run of 12V battery power.
For AC the best solution is a motor generator. Basically an iron
flywheel rides out any small dropouts in the utility power. They had
one for a mainframe computer at a place I worked at a long time ago.
But only that one output 280V at 400Hz as the computer required 400Hz
power.
On Mon, Jul 25, 2016 at 2:43 AM, David J Taylor
david-taylor@blueyonder.co.uk wrote:
Chris,
Do you mean like these:
http://www.aelgroup.co.uk/products/agt.php
I have an old 75W unit somewhere....
--
Chris Albertson
Redondo Beach, California
I have never seen one which did not use a class-D output with L-C
filtering. Total efficiency is in the 84 to 92 percent range.
These days they also include power factor correction on their line
input so they can be used to apply power factor correction to any
load.
Refurbished ones are available online for reasonable prices.
Another option if you just want superior line filtering is an active
power conditioner which is an online UPS using a capacitor bank
instead of batteries. They should be less expensive since they do not
have the large impedance jump down to 48 volts but in practice they
are not because of a small market compared to online UPSes. Some
online UPSes will operate this way without batteries.
On Mon, 25 Jul 2016 08:28:45 -0700, you wrote:
...
The other option is an on-line UPS, one that always runs off the
battery. These are expensive if you need a good sine wave output.
The UPS has an output stage not unlike an audio amplifier. Not nearly
as efficient as MOSFET switches. (question: I'd guess that modern
versions would be designed with class-D output stages and have decent
power efficiency??)
...
Hi Chris:
The APC RS1500 uses what they call modified sine wave, but I call modified square wave, i.e. it's a square wave with a
couple of parts that are at zero volts.
Don Lancaster promoted "Magic Sinewaves" where a pulse modulated waveform drives an H-bridge. The leading and trailing
edges are determined using the idea of FFT so that all the harmonics up to some number (typically 9 to thirty something)
are zero. There were also 3-phase versions. But he no longer sells any hardware.
PS I'm looking for a source of 3-phase 400 Hz 115 VAC to power a North Finding Gryo.
http://www.prc68.com/I/WildARK2.html
--
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
The lesser of evils is still evil.
-------- Original Message --------
Yes, "ferroresonant" is also called CVT. Typically rather than buying
just the transformer you buy a box that has one in it but also some
other components to clip spikes (some MOVs) and and LC low pass
filter. I know it seems a saturated core might produce a non-sine
wave but current CVTs have very low distortion.
The other option is an on-line UPS, one that always runs off the
battery. These are expensive if you need a good sine wave output.
The UPS has an output stage not unlike an audio amplifier. Not nearly
as efficient as MOSFET switches. (question: I'd guess that modern
versions would be designed with class-D output stages and have decent
power efficiency??)
The best solution is what the phone companies did. The telco style
equipment, like computers and such runs off 48VDC. and batteries are
connected in parallel from a "battery room". If designing your own
GPSDO, it should be built to run of 12V battery power.
For AC the best solution is a motor generator. Basically an iron
flywheel rides out any small dropouts in the utility power. They had
one for a mainframe computer at a place I worked at a long time ago.
But only that one output 280V at 400Hz as the computer required 400Hz
power.
On Mon, Jul 25, 2016 at 2:43 AM, David J Taylor
david-taylor@blueyonder.co.uk wrote:
Chris,
Do you mean like these:
http://www.aelgroup.co.uk/products/agt.php
I have an old 75W unit somewhere....