A+ Hardware Service Technician: Upgrades, Troubleshooting and Preventative Maintenance

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Power

There are several classifications of power problems you may experience with the normal A/C power.

Surges: a surge, also called a spike, is a very brief change in voltage

Sags: a brief dip in available voltage (similar to a very short brown-out)

Brownout: a sag which is there for an extended period of time. With a brown-out, you still have power coming through, just not the normal amount

Blackout: complete loss of power

UPS

A UPS, an Uninterruptible Power Supply, is a battery backed up unit which provides continuous power (for a short period of time) in case of a brownout, sag, or blackout.

There are two classifications of UPS: online and offline. An online UPS is one which supplies power from its battery and recharges from the incoming power. An offline unit switches to battery power when power loss is sensed.

An online UPS protects the machine more by providing a steady voltage.

Things to Consider About UPSs

UPSs are very useful devices though there are several elements you need to consider when purchasing or installing them.

The cost is an important issue to consider. For a workstation, a simple 10-20 minute UPS can range from $50 - 150. For a machine which requires a significant amount of power (e.g. a server or a whole rack of servers) the costs can go up significantly.

One other important thing to consider with a no-failure environment is more than one UPS combined with a generator. At one position I held, we had a server room with around 25 servers. Each server had dual power supplies which were balanced between different industrial strength surge protectors. The surge protectors were balanced between two large online UPSs. These UPSs were designed to provide power to the server room for about an hour without failure. With this balanced approach, if one power supply, one surge protector, or one UPS failed, the server could still function.

One other consideration for server room battery backups - don't forget to provide UPS units for the network hardware! I have seen enterprises setup an exquisite battery backup system for the servers to keep them up in case of power failure but fail to support their switches. When a power loss would occur, the employees would lose network access, thus oftentimes losing what they were working on.

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