Generators are a key to data center reliability. Supplementing a battery-based uninterruptible power supply (UPS) with an emergency generator should be considered by all data center operators. The question has become increasing important as super storms such as Hurricane Sandy in the Northeast United States knocked out utility power stations and caused many downed power lines, resulting in days and weeks of utility power loss.
Beyond disaster protection, the role of a backup generator to provide power is important when utility providers consider summer rolling blackouts and brownouts and data center operators see reduced utility service reliability. In a rolling blackout, power to industrial facilities is often shut down first. New data center managers should check the utilities contract to see if a data center is subject to such utility disconnects.
Studies show generators played a role in between 45 and 65 percent of outages in data centers with an N+1 configuration (with one spare backup generator). According to Steve Fairfax, President of MTechnology, “Generators are the most critical systems in the data center.” Mr. Fairfax was the keynote speaker at the 2011 7×24 Exchange Fall Conference in Phoenix, Arizona.
What Should You Consider Before Generator Deployment?
Generator Classification / Type. A data center design engineer and the client should determine if the generator will be classified as an Optional Standby power source for the data center, a Code Required Standby power source for the data center, or an Emergency back-up generator that also provides standby power to the data center.
- Generator Size. When sizing a generator it is critical to consider the total current IT power load as well as expected growth of that IT load. Consideration must also be made for facility supporting infrastructure (i.e. UPS load) requirements. The generator should be sized by an engineer, and specialized sizing software should be utilized.
- Fuel Type. The most common types of generators are diesel and gas. There are pros and cons to both as diesel fuel deliveries can become an issue during a natural disaster and gas line feeds can be impacted by natural disasters. Making the right choice for your data center generator depends on several factors. The fuel type needs to be determined based upon local environmental issues, (i.e. Long Island primarily uses natural gas to protect the water aquifer under the island), availability, and the required size of the standby/emergency generator.
- Deployment Location. Where will the generator be installed? Is it an interior installation or an exterior installation? An exterior installation requires the addition of an enclosure. The enclosure may be just a weather-proof type, or local building codes may require a sound attenuated enclosure. An interior installation will usually require some form of vibration isolation and sound attenuation between the generator and the building structure.
Exhaust and Emissions Requirements. Today, most generator installations must meet the new Tier 4 exhaust emissions standards. This may depend upon the location of the installation (i.e. city, suburban, or out in the country).
- Required Run-time. The run-time for the generator system needs to be determined so the fuel source can be sized (i.e. the volume of diesel or the natural gas delivery capacity to satisfy run time requirements).
What Should You Consider During Generator Deployment?
- Commissioning The commissioning of the generator system is basically the load testing of the installation plus the documentation trail for the selection of the equipment, the shop drawing approval process, the shipping documentation, receiving and rigging the equipment into place. This process also should include the construction documents for the installation project.
Load Testing Typically, a generator system is required to run at full load for at least four (4) hours. It will also be required to demonstrate that it can handle step load changes from 25% of its rated kilowatt capacity to 100% of its rated kilowatt capacity. If the load test can be performed with a non-linear load bank that has a power factor that matches the specification of the generator(s) that is the best way to load test. Typically, a non-linear load bank with a power factor between 75% and 85% is utilized.
- Servicing The generator(s) should be serviced after the load test and commissioning is completed, prior to release for use.
What Should You Consider After Generator Deployment?
- Service Agreement. The generator owner should have a service agreement with the local generator manufacturer’s representative.
- Preventative Maintenance. Preventative Maintenance should be performed at least twice a year. Most generator owners who envision their generator installation as being critical to their business execute a quarterly maintenance program.
- Monitoring. A building monitoring system should be employed to provide immediate alerts if the generator and ATS systems suffer a failure, or become active because the normal power source has failed. The normal power source is typically from the electric utility company, but it could be an internal feeder breaker inside the facility that has opened and caused an ATS to start the generator(s) in an effort to provide standby power.
- Regular Testing. The generator should be tested weekly for proper starting, and it should be load tested monthly or quarterly to determine that it will carry the critical load plus the required standby load and any emergency loads that it is intended to support.
Maintenance. The generator manufacturer or third party maintenance organization will notify the generator owner when important maintenance milestones are reached such as minor rebuilds and major overhauls. The run hours generally determine when these milestones are reached, but other factors related to the operational characteristics of the generator(s) also apply to determining what needs to be done and when it needs to be done.
To learn more about PTS recommended data center generators, contact us or visit (in alphabetical order):
- Bloom Energy – Energy Server Generator Solution
- Caterpillar – Data Center Diesel Generators
- Caterpillar – Data Center Gas Generators
- Cummins – Data Center Diesel Generators
- Cummins – Data Center Gas Generators
- Generac – Data Center Diesel Generators
- Generac – Data Center Gas Generators
- MTU Onsite Energy – Data Center Diesel Generators
- MTU Onsite Energy – Data Center Gas Generators
To learn more about PTS Data Center Solutions available to support your Data Center Electrical Equipment & Systems needs, contact us or visit:
- PTS Electrical Equipment & Systems Solutions
- Data Center Commissioning
- Delivery & Rigging Coordination
- Data Center Power & Cooling Systems Analysis
- Data Center Availability & Risk Assessment
- Data Center Support Infrastructure Equipment Services
- Data Center Maintenance (DCMMS)
- Managed Services – Outsourced IT & Facility Solutions