Is my Back-UPS 550G faulty - not switching back to mains after outage ?

[sbsnet_apc]

This was originally posted on APC forums on 8/11/2013

---

Having some strange behavior with my brand new 550G.

UPS is setup to support a Windows 7 machine, running powerchute personal edition. Software is configured to shutdown PC after 5 minutes.

When I disconnect the mains power, the battery kicks in keeping the PC alive, and after 5 minutes - the PC is powered down into hibernation.

When I reconnect the mains power -

1 the PC starts rebooting out of hibernation but display on UPS remains showing battery...

2 the PC once fully booted, sits there for 20 seconds or so - and then the UPS completely disconnects the PC - shutting it down power cut style - crashing it.

3 After another 10 seconds, the display on the UPS then flicks from battery to mains power display.

this behavior is totally repeatable and totally wrong ....

Any suggestions  ? Mains power is quite normal voltage - 240V (UK)

Thanks,

Julian

Birmingham, UK

[BillP]

This reply was originally posted by Angela on APC forums on 8/12/2013

---

I think you might be interrupting the pre-programmed UPS timeline while the UPS is in the middle of its reboot cycle. So I think it is working as designed.

Just because you reconnect the mains power after the shutdown/hibernation begins, it does not mean the UPS has completed its process. Please review the timelines below and I'd try your testing again and leave the UPS unplugged for several minutes and let it turn off completely and go to low voltage sleep mode and then plug it back in. Don't plug it immediately back in as soon as the computer hibernates.

Shutdown time line, software not installed:

1. UPS goes to battery, the on battery beep sounds

2. The UPS will sound the on battery beep until it reaches the last few minutes of run time when the battery has been depleted.

3. When the unit reaches the last few minutes of battery life it will then sound its low battery alarm.

4. Just before the battery is completely exhausted the ups will turn itself off.

5. If the UPS went to battery due to a brown out the unit at this point will be in LVSM (low voltage sleep mode) until the voltage becomes acceptable again.

PowerChute Personal Edition default shutdown time line:

1. UPS goes to battery and PCPE starts its preserve battery power counter.

2. When the counter expires it sends a command to the UPS to start counting its turn off delay and then commands the OS to shutdown.

3. The operating system shuts down and the UPS continues to count its turn off delay. (Once the UPS finishes counting its turn off delay it will reboot and nothing can stop this from happening.)

4. The UPS cuts power to the outlets then rechecks to see if the incoming power is acceptable. If it is not, it waits there until power returns.

5. If the UPS went to battery due to a brown out the unit at this point will be in LVSM until the voltage becomes acceptable again.

[sbsnet_apc]

This was originally posted on APC forums on 8/13/2013

---

Thanks for the info... Much Appreciated...

Hmm.. sounds like this is a design fault then - if power returns before the UPS reboot cycle is complete - the UPS will effectively un-hibernate and then crash a protected device... Not Good...

If I programme my PC to shut down after 5 minutes, and then there is a one minute reboot cycle - I am effectively unprotected for any power cuts that last between 5 & 6 minutes...

Is this correct ?

Ideally, if the UPS is in its reboot cycle - and power returns -  it should NOT provide any power to connected devices until reboot is complete - the would solve everything...

Does the smart line of UPS have the same behavior ? I may just upgrade....

[BillP]

This reply was originally posted by Secret on APC forums on 8/13/2013

---

Hi sbsnet,

Hopefully I can help to clarify the need for this function. Once the Powerchute software reaches the user designated parameters for shutdown, the Powerchute software initiates a system Shutdown as if the User themselves had initiated a system shutdown. Just like the User initiated Shutdown, this can not be disrupted. Interruption of the system shutdown at this point would result in system errors and loss of materials designated for hibernation. In addition, utility power when lost may fluctuate randomly while the electrical provider is attempting to re-stabilize. A momentary return of utility power may not be sufficient enough to support the UPS in the Online state. Due to the limited runtime present in the UPS and the inherent obligation of the unit to protect the computer and the data contained there-in, interrupting the System Shutdown prematurely would be considered an unnecessary risk, as the UPS may not have retained enough "runtime" to initiate and complete a System Shutdown a second time.

[sbsnet_apc]

This was originally posted on APC forums on 8/13/2013

---

Thanks for that.

For the record - how long is the turn off delay for a back-ups 550g (ie how long before the UPS reboots upon receiving a reboot signal from the PCPE software) ?

I guess its been designed to be just long enough for majority of slow devices to go into hibernation...

For the Smart range of UPS - do they behave in the same way ? and if normal power resumes BEFORE reboot of UPS has occured - will protected device get re-awoken and then promptly subjected to a power cut - which is what i'm observing ?

[BillP · Accepted solution]

This reply was originally posted by Secret on APC forums on 8/14/2013

---

Hi Julian,

The symptom you have indicated seeing during your testing is not what is expected from the unit during normal operation. I believe the issue may lie in the method we are using to test this device. By removing the plug from the wall, we are eccentially resetting the unit's connection to neutral and earthground. In doing so, I believe we are effectively reinitiallizing the computer powersupply. If this same scenario were to occur naturally while still connected to the utility outlet, the computer would not return to an "ON" status until the UPS had completely cycled power to iteself and returned to an Online state. This scenario would occur for both Back-UPS and Smart-UPS units. The best way to test the operation of the units would be to lower or remove utility power with the use of a Variac device. This would be the best method for simulating a poweroutage.