Sorry to provide a personal answer but in 36 years of measuring CO battery I
have never seen it fall below 46 volts and never more than 52 volts. This
is regular plant voltage. Some special service equipment bays provide as
much as -72 volts and -130 volts for special circuits.
A typical plant of many LARGE 48 volt batteries receives a float charge of
-51 to -53 volts from the commerical power supplied through large power
rectifiers. If commercial power is lost and the standby generator fails,
the battery plant will provide -48 volts for quite some time before it
starts to drop to -46 volts. During a disaster it might be possible to drop
below that but even during the long dropouts in Chicago I never saw plants
to drop below -46 volts. This of course depends on the plant design and the
reliability of the standby power system.
My hat is off to Dave Spencer for looking up all of those requirements. If
I measured -57 volts I would think something is very wrong. Same with -40
volts.
Old Don
Nice work!!!
-40.5 to -57.0 VDC ETS 300 132-2:1996
{} -42.75 to -56.7 VDC ANSI T1.315:1994
{} -40.0 to -57.5 VDC AT&T NEDS 9069:1999
{} -42.5 to -56.5 VDC GR-499:1995 (-40.0 to -57.7 objective)
-----Original Message-----
From: Dave Machado - Network Service Providers Division
To: [email protected]
Cc: [email protected]
Sent: 2/16/2001 1:46 AM
Subject: RE: CO Battery output voltage range
Hello Tom K, Don H, David S
Thanks for this very valuable summary.
I do believe that there are two other relevant items worthy of note
in this matter, they are
1) where is the voltage being measured, and
2) what is "real world" duration/frequency of occurances
of -Vdc low limit.
I will address item 1 here.
Can you gentlemen shed some light on duration/occurances per year of
-40Vdc
appearing at products input power connectors or at the power
distribution
frames (PDFs)? Is it greater than 3 hours? Thanks
GR 499
-42.5 to -56.5 VDC is measured at the power distribution frame.
-40.0 to -57.7 objective is measured at the input connector of
Product (shelf level computer, line card bay,
etc).
-42.0V minimum and 56.7V Vdc maximum are respectively the
mandated
low (discharge) and high (charging) limits of the power plant
operating voltage measured at the at the battery stack(s).
ETSI 300-132-2
Is vague about where the voltage may appear (be measured),
due to the element of negotiation required (supplier/buyer)
to define location were power terminals connect to the
system block (interface A).
Thus measurement could be made at the line ups PDF or at input
connector to computer, line card bay, etc.
-40.5 to -57.0 VDC, is normal service steady state voltage
range for dc system having nominal voltage value of -48Vdc.
AT& T NEDs
Is clear that -40.0 to -57.5 VDC is meausred at the lugs of
the network equipment unit (I interpret this to mean input
connector to computer, line card bay, etc.)
end
{} From: David Spencer <[email protected]>
{} To: "'[email protected]'" <[email protected]>
{} Cc: [email protected]
{} Subject: RE: CO Battery output voltage range
{} Date: Thu, 15 Feb 2001 16:54:18 -0800
{} MIME-Version: 1.0
{}
{} Hey Tom,
{} There are a number of different flavors you can pick. For
Telcordia, the
{} objective in GR 499 has the widest swing. We do ours from -40 to
-60VDC.
{} The extra head doesn't cost us anything as it keeps us within the
SELV
{} limits and makes us look good to customers who wonder why the other
guy's
{} equipment only goes to 57.5VDC, the inference being ours is better.
Here is
{} a list of various standards requirements:
{}
{} -40.5 to -57.0 VDC ETS 300 132-2:1996
{} -42.75 to -56.7 VDC ANSI T1.315:1994
{} -40.0 to -57.5 VDC AT&T NEDS 9069:1999
{} -42.5 to -56.5 VDC GR-499:1995 (-40.0 to -57.7 objective)
{}
{} Have a Great Day!
{} Dave
{}
{} -----Original Message-----
{} From: [email protected] [mailto:[email protected]]
{} Sent: Thursday, February 15, 2001 1:23 PM
{} To: [email protected]
{} Cc: [email protected]
{} Subject: CO Battery output voltage range
{}
{}
{} Hi All,
{} I am trying to determine the appropriate Telcordia standard number
and title
{} which defines the absolute minimum and maximum acceptable output
voltages
{} for a CO battery plant. I suspect the range is something like 42VDC
absolute
{} minimum and 56VDC absolute maximum, but it would help to have a
reference.
{} Also, are there any RBOC generated docs that cover this?
{}
{} Thanks.
{} Tom Lavka
{} Copper Mountain Networks, Inc.
{} 10145 Pacific Heights Blvd., Suite 100
{} San Diego, CA 92121
{} Voice:(858)410-7110
{} Fax: (858)410-7286
{} email:[email protected]
====================================================================
David A Machado
Sun Microsystems
Trinity Court
Wokingham Road
Bracknell, Berkshire
United Kingdom, RG42 1PL
Tel: +44 (0)1344 316741
Fax: +44 (0)1344 300704
=====================================================================
