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Making a Hybernating UPS and PC System

For Unattended PC Systems, it is essential to have the PC and the UPS set up for Hybernation.

What is Hybernation:

XP allows a PC and a UPS to control the PC into a special shutdown hybernation mode.

In a normal case, if the AC power is removed a PC will stop and if the AC power is reapplied it will not re-start without pushing the power button.

In a hybernate case, if the AC power is removed a PC will stop and if the AC power is reapplied it will re-start without pushing the power button.

This mode is selected in the control panel in smost PCs computers and at BIOS level in others.


However that isn’t the end of the story. The UPS will monitor the AC Power and talk via a serial or USB port to the UPS control software in the PC.

When the AC Power turns off, the UPS will sense this and tell the PC — “Power Off”, and will also continue the PC’s operation on battery backup.

At some point the UPS will need to save the RAM state of the PC and shut down the PC, as the batteires will run low. It does this control using the Serial or USB cable and commands to the software in the PC.

What to do when you get your new UPS:-

Suggestion 1:

Before you connect your UPS to the computer, ALWAYS do this.

Charge the UPS battery, by plugging the UPS into the AC mains wall socket and leave it charging for at least 12 hours. This will give the UPS battery an excellent start in it’s service for you.

Suggestion 2:

After the charge, connect the computer to the UPS. Next, power up the UPS and the computer, then turn the AC mains power off at the wall. The computer will now run off the UPS battery. Verify that everything on the computer runs correctly and then turn back on the wall AC mains. Don’t run the computer too long on the battery, always be gentle to the battery and it will be your life line when you need it.


Don’t and I mean DON’T see how long the computer will run off the battery and let it run until it stops. Battery life is determined by several factors but the biggest factor is how badly abused they are, deep discharges will shorten the life.

Suggestion 3:

If your UPS can be controlled by Shutdown Software, please install the software. Then trial the software and make sure the UPS shuts down after a programmed time. The software manual will explain this in detail. The reason for this software is not only to safe guard your work on the computer but also it will protect the UPS battery from being discharged to deeply, thereby prolonging its life. Don’t make the “up time” too long, just enough to get your work finished and saved.

Suggestion 4:

Another scenario.At night when leaving the work site, some users turn their computers off and then also turn the mains AC power off at the wall but do not turn the UPS power switch off. If you do this, the UPS will continue to run over night or the weekend and will discharge the battery. If this is over a weekend, on Monday morning the battery will most likely be completely discharged and the UPS will not restart when you turn the wall AC mains back on. As a good rule, never turn the UPS off or the AC mains off feeding it.

Some other tips:
  • Don’t put anything over the ventilation slots on the UPS, especially the sticky UPS caution labels. The UPS will get hot if you do this.
  • Don’t put the UPS in enclosed space, like a cupboard. The UPS will also get hot.
  • Put the UPS on the floor in an open area so air will circulate around and through it

At the PK and TrippLite Service Center, we follow these suggestions closely and we have PK or TrippLite product on every computer and on our PABX.

We always want to hear any useful UPS tips from users, email info@mastec.co.nz with your tip.

TIP: All suggestions are important but number 4 is the biggest cause of problems, especially with UPS models that don’t have a beeper to tell you they are running off the battery when you turn the AC mains off.

Controlling Alarm Device with your UPS Dry Contact outputs

If you have an alarm system that requires driving with dry contacts from a UPS we can do this.

TrippLite, Powercom, JST/Power Kinetics, and APC all have dry contacts either in their UPSs or as an accessory.

A question that is often asked, is can I use Open Collector on dry contact systems, because many UPSs have open collector outputs and not relay closures.

Companies like Alpha, TrippLite and lower cost APCs have Open Collector outputs.

The answer is usally yes: If the alarm system is controllable with signal levels from 0-24VDC this is usally possible.

The reason: If you measure the dry contact inputs of an alarm, they are excited with a bias voltage. When the dry contact is open, this bias voltage stops the alarm system from running, when the dry contacts close the bias voltage is shorted to ground via a bias resistor and the alarm runs.

An Open Collector system does exactly the same thing.

However check the dry contact bias voltage can be accepted by the open collector outputs.

I am searching for good graphics on this to expalin it, if you have some send them to me please.

What to do when you get your new UPS

Controlling Alarm Device with your UPS Dry Contact Outputs

Making a Hybernating UPS and PC System