news / tech talk

Generator Use

by Lee LeClair
As seen in Inside Tucson Business

Recently, I last wrote about the importance of reliable electrical power and the role of uninterruptible power supplies (UPS) as part of a reliable power strategy. For many businesses, a UPS provides sufficient mitigation for the risk of a power sag, spike, or short term interruption. With software to automatically shutdown attached systems, the risk of data corruption can be minimized. However, if systems must always be up and online, then one must plan for power losses longer than 15 minutes or so.

There are two main ways of dealing with power losses longer than 15-20 minutes: host your systems at a data center or provide your own generators and electrical switching systems. There are considerable upfront costs and complexity associated with providing your own contingency power in a long term outage situation, so hosting critical systems at a data center has several advantages. First, the data center provides the expensive electrical infrastructure which includes UPS, auto-switching circuits, and generators. Second, the data center provides the knowledgeable personnel to maintain and test these systems as well as the logistics of keeping generator fuel on hand. Finally, a data center will typically have the ancillary services required (air conditioning, fire detection and suppression systems, etc.) necessary for critical systems. The primary issue with data centers is their recurring cost. Data centers must cover their extensive space, personnel, and infrastructure costs. Also, some businesses want their systems to be physically in their own control.

The second option is to obtain your own electrical infrastructure to maintain power during outages longer than 15-20 minutes. When considering this option, keep in mind that you must estimate for the infrastructure you plan to keep running and that includes the supporting systems like air conditioning and all your network equipment to your perimeter. If you fail to put your AC on emergency power then your servers will only continue to run until they get hot enough to drop due to a component failure which could be much more serious than a power loss shutdown. Electrical power is complex business so I strongly recommend working with an electrician to get things done. Basics for consideration are the circuits you will need to have on emergency power, the electrical load you will need to maintain (in VA or Watts), the speed and sizing of electrical switching gear, and the capacity and type of generator(s) you will need.

Many types of generators are available including portable units, fixed units, systems that run on gas, diesel, propane, or natural gas. Pretty much all of them rely on a combustion engine to operate and that means they are noisy and create exhaust just like a car. Keep that in mind as well as the physical protection they will require before selecting where the generator will go. As far as fuels go, consider that must liquid fuels have a shelf life so you will need to work out a schedule for how to cycle fuel through your inventory so that you always have a supply of good fuel for whatever length of outage time you are planning for. Natural gas systems are great in that they eliminate the need for this fuel management hassle but these types of systems are often not available in commercial locations. Opting for your own electrical infrastructure also implies regular maintenance and testing of the equipment. I cannot stress enough the importance of regular running your generators and conducting full tests of electrical switch-overs to ensure the switching gear and everything will operate as planned.

It isn't a simple task keeping systems up reliably 24x7 so weigh the alternatives carefully and factor in the personnel costs of commercial hosting vs providing your own backup power. Plan well though and you should be able to meet your uptime goals.
