UPS has to see AC before providing backup

This is the place for any magazine-related discussions that don't fit in any of the column discussion boards below.
Post Reply
don87109
Posts: 17
Joined: Sat Jan 02, 2010 5:19 pm
Contact:

UPS has to see AC before providing backup

Post by don87109 » Fri Nov 09, 2012 5:03 pm

I have a couple Of UPS's that seem to have a strange limitation. They have to see AC before they become "armed". IOW, if they are not plugged in when the power fails you can't use them. Similarly, if when operating on battery and it becomes discharged you cannot replace it with a fresh battery - once the battery is changed it has to see AC first to become armed. Of course if you were on UPS when the battery discharged you don't have AC power so you are dead in the water.

One of the UPS's is made by APC and a quick look at the manual doesn't seem to address this issue.

Makes no sense to me why they have this design limitation.

Anybody have any insight or workaround?

P.S. I have a separate inverter and battery that provides AC and I have used it to kick start these UPS when I encounter this limitation, but that seems like an outrageous requirement.

Don

User avatar
dacflyer
Posts: 4420
Joined: Fri Feb 08, 2002 1:01 am
Location: USA / North Carolina / Fayetteville
Contact:

Re: UPS has to see AC before providing backup

Post by dacflyer » Fri Nov 09, 2012 6:04 pm

i know how you feel..it is kind of a dumb feature
i do not seem to have this problem with tripplite ups's
not sure how to get around that problem.

User avatar
sofaspud
Posts: 531
Joined: Wed Feb 13, 2002 1:01 am
Location: San Antonio, TX
Contact:

Re: UPS has to see AC before providing backup

Post by sofaspud » Sat Nov 10, 2012 2:28 am

What model UPS do you have?
I have a couple of APC units from the 250/400/600 line. They were "orphaned" due to a hardware upgrade
so I gave them a new home. I've never used them, but was able to obtain schematics at the time. A quick
look suggests that a simulated "AC Fail" signal(s) might fool it into battery operation.
I have to admit, though, that I don't quite understand why you want to use a UPS as a simple inverter.

don87109
Posts: 17
Joined: Sat Jan 02, 2010 5:19 pm
Contact:

Re: UPS has to see AC before providing backup

Post by don87109 » Sat Nov 10, 2012 7:09 am

sofaspud wrote:What model UPS do you have?
I have a couple of APC units from the 250/400/600 line. They were "orphaned" due to a hardware upgrade
so I gave them a new home. I've never used them, but was able to obtain schematics at the time. A quick
look suggests that a simulated "AC Fail" signal(s) might fool it into battery operation.
I have to admit, though, that I don't quite understand why you want to use a UPS as a simple inverter.
I have two UPS's that are my primary focus.

One is an APC 900xl. I believe it is a true sine wave inverter and I want to use it on equipment where my modified sine wave inverter doesn't work. To buy a true sine wave inverter is a little costly (especially when I have the 900xl). Although I'll probably buy a true sine wave rather than spend a lot of time digging into the 900xl circuitry to solve the problem.

The other UPS is built into my Verizon telephone/cable support equipment. It's battery is only good for 8 hours and when Hurricane Sandy hit my power was out for many days. Unfortunately, when the battery died I couldn't easily substitute a car battery. I eventually succeeded by kick starting it with my modified sine wave inverter.

Although I have a generator for long-term power failure I like to use the inverters at night to eliminate the noise.

User avatar
haklesup
Posts: 2948
Joined: Thu Aug 01, 2002 1:01 am
Location: San Jose CA
Contact:

Re: UPS has to see AC before providing backup

Post by haklesup » Fri Nov 16, 2012 1:37 pm

maybe they had problems with the output powering on while in storage (or during factory assembly) which would deep discharge a battery and this was the solution. Its hard to know for sure. Sometimes it has nothing to do with the application but everytrhing to do with manufacturing procedures.

User avatar
dacflyer
Posts: 4420
Joined: Fri Feb 08, 2002 1:01 am
Location: USA / North Carolina / Fayetteville
Contact:

Re: UPS has to see AC before providing backup

Post by dacflyer » Fri Nov 16, 2012 7:27 pm

hi there again.. i just changed a lot of batteries in several APC 1400's here
i have found out if you hold the power button in.. and the second it beeps, let go.,and the unit will fire up with out AC.
if you hold the button in too long after the beep the unit will not start.
give it a try, let us know if it works for you..

User avatar
jollyrgr
Posts: 1289
Joined: Thu Jan 03, 2002 1:01 am
Location: Northern Illinois
Contact:

Re: UPS has to see AC before providing backup

Post by jollyrgr » Mon Nov 26, 2012 3:59 pm

I have worked on APC UPS units from 350VA to 1500VA and every one could be started without AC. (I have not tried this with the 150KVA units though. These will easily run a house.) Turning on a UPS without AC power is called "Cold Starting". Most of the time it is the method Dakflyer suggests. Sometimes you might have to wait a bit after the beep before you let go. Other times you have to wait for the beep, let go, then push the button a second time. Another method still is to push the button and you will hear a slight chirp. There will then be a long beep and you must let go of the button while the long beep is sounding. This last method is covered in the APC manual. I found one version here:

http://213.175.108.87/apc_smart-ups_620va.pdf

See the last section of the first page.

I do not recall the exact method to silence the annoying beep once it is cold started. Some units have a speaker with a slash through it that is obvious. Others you tap the power button briefly. I would try this first so you don't actually dump the load.
No trees were harmed in the creation of this message. But billions of electrons, photons, and electromagnetic waves were terribly inconvenienced!

Post Reply

Who is online

Users browsing this forum: No registered users and 13 guests