Mike,
Thanks for the clarification...And the information provided is All good and
helpful. But this is where I'm confused....
With "constant" switching
What makes characteristics of "Constent" switching.
It should only switch ONCE or TWICE unnecessarilly (which is not
"Constent"), when the backup generator first kicks in.
Not sure why thats considered a big problem.
Unless one is thinking ahead, that the UPS Batteries may not be good enough,
at the time a Power failure occurs and Generator activity is required.
Unless suggesting that running on the generator, will cause constant voltage
drops, causing repeat UPS false detects.
If your supply is not clean, the UPS will not fix it.
Most UPSs made by APC above 500VA, both low cost Pulse Modulation models and
Smart Online (pure Sinewave) models have Voltage Regulation built-in, and
minor surge protection (350 joules or so) for the purpose to "clean up the
power". With the exception of the really cheapo Desktop models shaped like
thick surge protector trips.
I recognize that the switch setting on the APC UPS, is what allows one to
set the Voltage Variation Range to be less sensitive to the Voltage drops
and such, possibly solving the problem using them with generators.
Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband
----- Original Message -----
From: "Mike Hammett" <[EMAIL PROTECTED]>
To: "WISPA General List" <wireless@wispa.org>
Sent: Sunday, July 01, 2007 2:14 PM
Subject: Re: [WISPA] Low cost generator
Unclean power will cause it to switch back and forth to\from the battery.
As said, this is an adjustable setting on the UPS.
What Felix is talking about is the switch from line to battery is detected
as zero voltage by the powered equipment. There is no doubt that this
exists and is an issue that more sensitive electronics have problems with.
With constant switching, the powered equipment may fail. If your supply
is not clean, the UPS will not fix it. I am unsure if clean power is
produced when on battery. A line conditioner's job is to clean up the
power.
-----
Mike Hammett
Intelligent Computing Solutions
http://www.ics-il.com
----- Original Message -----
From: "Tom DeReggi" <[EMAIL PROTECTED]>
To: "WISPA General List" <wireless@wispa.org>
Sent: Sunday, July 01, 2007 12:39 PM
Subject: Re: [WISPA] Low cost generator
automatic transfer does not take place at
one quarter of a cycle in a 60 cycle per second AC
power supply, then the sensitive logic controllers of
any network equipment, PLCs, etc will detect the
automatic transfer as a possible zero voltage
condition.
So What? Does that matter, as it is a one time event when the initial
transfer occurs?
So the 750VA UPS, temporarilly switches to the UPS battery standby power,
keeping Radios up, until the Generator power stablizes as on, then UPS
switches back to line power from the generator. IF the generator
delivers unclean unstable power so what, that is the purpose of the small
APC UPS to keep clean power going to the radio devices. So what if the
UPS regularly switches back and forth from battery to Line voltage, as
long as the switch is quick within required tolerances, and that it is
not to frequent to drain the UPS battery.
From my experience, when the UPS did not do its job, it was because the
UPS
had a bad battery that could not handle the load, or a low grade UPS that
did not have a fast enough transfer time itself, not a flaw in the
generator's or its autoswitch.
What I had understood that George had said was not the the UPS switched
back and forth between line and battery, but he said the UPS itself kept
switching OFF and ON, as if the UPS was then malfunctioning.
What I was wondering was what type of power output was the problematic
generator putting out? Pure Sinewave or Pulse Modulated. Many low cost
devices put out PulseModulated, which is easier to regulate, to put out
regulated power. However, the Squared edge nature of the wave can be
interpreted by a UPS further downstream as Bad Power, and possibly even
damage the downstream UPS. Which is a reason one is never supposed to
install a ppure sinewave UPS downstream of a Pulsemodulated UPS.
We had designed some battery backup systems usign Tripplite's Power
Inverters (pulse modulated output), which worked great, but we could not
use APC Online UPS (puresinewave) UPSes in the racks. To add better
surve protection we put the protection directly in the Panel box with AC
surge protection. To check status of power outage, we install a cheap
Linksys router, plugged directly into the AC outlet prior to the backup
power systems, and then when this device stops responding, we know that
there is not power beign sent to it. (yes there is an issue where the
Linksys could lock up, and then us not know if it is the Linksys locked
up or no power). One thing we were considering was to plug it inline with
the Generators AC output feed, so teh Linksys bydefault is always off,
and then when generator power kicks in the Linksys powers up, and if we
can get to it, we know we are runnign on backup power.
So the point I'm making is, many generators, just put out raw voltage
without regulation, purposely, so a UPS can be used after it to protect
against drops and surges, and so Rack based UPSes do not need to be
removed. The acception to this is if it has high end voltage regulation
that puts out Pure Sinewave power.
Its actually relevent that we are specifically talkign about the APC
750VA rackmount UPS. I'm assuming you are talking about the Pure sine
wave Online version.
That model is a sweat spot model because it is inexpensive, has SNMP
model support, and it allows external batteries, and uses the slighly
larger battery type, which enables longer run-time. Its worth finding a
generator compatible with it. I was surprised to hear you were having the
problem you represent.
Thats my take on it. But will be interesting what you guys find out on
what ends up working best.
Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband
----- Original Message -----
From: "Felix A. Lopez" <[EMAIL PROTECTED]>
To: "WISPA General List" <wireless@wispa.org>
Sent: Saturday, June 30, 2007 3:33 PM
Subject: Re: [WISPA] Low cost generator
George/Mike: I worked for 6 years in deep UPS and
power quality at PG&E in Silicon Valley including
IEEE1159 and CBEMA curve. Our field work demonstrated
that if an automatic transfer does not take place at
one quarter of a cycle in a 60 cycle per second AC
power supply, then the sensitive logic controllers of
any network equipment, PLCs, etc will detect the
automatic transfer as a possible zero voltage
condition. The weblink provided below did not specify
the automatic transfer switch cycle time (see pages 18
to pages 23). A true UPS with continuous power will
actually provide your utility power source through a
battery system including power conditioning along
with generator backup. I had the opportunity to work
with the FAA in Fremont, California which has true
UPS> it was quite a setup.
So you may want to ask at what level you of continuity
you need for your wireless network.
I know of a few subject matter experts in the industry
should you need a consultant.
Felix
Energy and Wireless practioneer
Silicon Valley Area
--- Mike Hammett <[EMAIL PROTECTED]> wrote:
You can change this all via the APC management
software.
-----
Mike Hammett
Intelligent Computing Solutions
http://www.ics-il.com
----- Original Message -----
From: "Eric Muehleisen" <[EMAIL PROTECTED]>
To: "WISPA General List" <wireless@wispa.org>
Sent: Saturday, June 30, 2007 12:23 PM
Subject: Re: [WISPA] Low cost generator
> Travis,
> How do you go about tweaking a UPS? We use APC
750's at most small tower
> sites. During the event of a power outage we use
1000watt generators but
> as you said...the UPS just shuts off and on,
repeatedly.
>
> -Eric
>
> Travis Johnson wrote:
>> Brad,
>>
>> You can adjust the sensitivity of the APC UPS's
to handle just about any
>> type of incoming power. We have run a tower off a
cheap Home Depot
>> 2000watt by adjusting the APC so it would not
keep switching off an on.
>>
>> Travis
>> Microserv
>>
>> Brad Belton wrote:
>>> We have found many (most all?) <10kW "job site"
type generators do not
>>> work
>>> well if at all with APC UPS. In the event of a
power failure we simply
>>> rent
>>> a 25kW towable diesel generator. Granted 25kW
is way overkill for most
>>> any
>>> HUB site, but apparently the larger generators
provide "cleaner" power
>>> that
>>> the APC UPS's are happy with.
>>>
>>> Does anyone have one of these 7kW Guardian
standby generators in use
>>> with
>>> APC UPS's? $1999.00 delivered with transfer
switch is a pretty strong
>>> deal!
>>>
>>> Best,
>>>
>>>
>>> Brad
>>>
>>>
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On
>>> Behalf Of Scott Reed
>>> Sent: Saturday, June 30, 2007 11:30 AM
>>> To: WISPA General List
>>> Subject: Re: [WISPA] Low cost generator
>>>
>>> The Guardian comes as small as 7KW for about
$2100 and goes up a long
>>> way from there.
>>> I have seen Guardians at cell sites and waste
water lift stations around
>>> here.
>>>
>>> George Rogato wrote:
>>>
>>>
http://www.electricgeneratorsdirect.com/catalog/product_info.php?products_id
>>> =538
>>>> I'm in the market for a generator and came
across this one.
>>>> The auto transfer switch and propane caught my
eye and I figured I'd
>>>> share it with the list.
>>>>
>>>>
>>>
>>>
>
> --
> WISPA Wireless List: wireless@wispa.org
>
> Subscribe/Unsubscribe:
> http://lists.wispa.org/mailman/listinfo/wireless
>
> Archives:
http://lists.wispa.org/pipermail/wireless/
>
--
WISPA Wireless List: wireless@wispa.org
Subscribe/Unsubscribe:
http://lists.wispa.org/mailman/listinfo/wireless
Archives: http://lists.wispa.org/pipermail/wireless/
____________________________________________________________________________________
Take the Internet to Go: Yahoo!Go puts the Internet in your pocket:
mail, news, photos & more.
http://mobile.yahoo.com/go?refer=1GNXIC
--
WISPA Wireless List: wireless@wispa.org
Subscribe/Unsubscribe:
http://lists.wispa.org/mailman/listinfo/wireless
Archives: http://lists.wispa.org/pipermail/wireless/
--
No virus found in this incoming message.
Checked by AVG Free Edition.
Version: 7.5.472 / Virus Database: 269.9.6/865 - Release Date: 6/24/2007
8:33 AM
--
WISPA Wireless List: wireless@wispa.org
Subscribe/Unsubscribe:
http://lists.wispa.org/mailman/listinfo/wireless
Archives: http://lists.wispa.org/pipermail/wireless/
--
WISPA Wireless List: wireless@wispa.org
Subscribe/Unsubscribe:
http://lists.wispa.org/mailman/listinfo/wireless
Archives: http://lists.wispa.org/pipermail/wireless/
--
Internal Virus Database is out-of-date.
Checked by AVG Free Edition. Version: 7.5.472 / Virus Database:
269.9.6/865 - Release Date: 6/24/2007 8:33 AM
--
WISPA Wireless List: wireless@wispa.org
Subscribe/Unsubscribe:
http://lists.wispa.org/mailman/listinfo/wireless
Archives: http://lists.wispa.org/pipermail/wireless/
