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Supplying Backup Power to Data Centers

Data centers are defined as a facility used to house computer systems and associated components; such as telecommunications (satellite communications and phone systems) and storage systems (hospitals, offices and internet providers). Data centers can house the following components:

• Backup power controls
• Redundant data connections and communications
• HVAC and Security Controls

Supplying uninterrupted power to data centers 100% of the time is critical for operations. Backup generators are used to insure the components have uninterrupted power. This article will explore:

• Function of backup generators
• EPA regulations
• Diesel Service and Supply

Function of Backup Generators

The function of the backup generator is to provide power when there is interruption of main power. Data center components do not easily tolerate power spikes due to switching from a normal to emergency power supply. When these components loose power (if only for a fraction of a second), a total restart is required. This could allow for system downtimes, startup issues and loss of in-process information.

All data centers operate in one of two modes:

• Normal Operation – Operating from supplied utilities
• Emergency Operation – Operating from standby generators. Data centers are equipped with redundant cooling systems for emergency operations

General Information

It is important to understand the components in the power distribution system in the facility the datacenter is located in. The main components in the power distribution are:

• Emergency Generator – Supplies power when utility power is not available
• Utility Power – Main power source for facility
• Automatic Transfer Switch – Routes utility or emergency generator power to switch gear
• Switch Gear – Routes utility or emergency generator power throughout
• Uninterrupted Power Supply – Consists of battery bank, charger and inverter

Normal System Operation

Utility Power is routed through the automatic transfer switch and into the switchgear. Switchgear is configured into critical and non-critical supplies. Critical supplies are components (such as data centers, security centers and UPS) that cannot have power interrupted. The UPS charger is supplied power to keep batteries charged. Non-Critical components (such as HVAC and Work stations) are do not have a redundant connection to the UPS Inverter.

Emergency Operation

When utility power is lost in the facility the following chain of events occur:

1. UPS supplies power to security and data center.
2. Emergency generator starts and automatic transfer switch transfers to emergency power.
3. Switch gear routes power to Critical and Non-Critical loads.
4. UPS transfers to normal operation and Data center and security are powered by emergency generator.
5. When normal power is resumed, the automatic transfer switch routes power to utility and critical and non-critical loads are powered.

Data center and security see no power interruption and continue to operate normally through power loss. Components such as HVAC and work stations may need to be reset to regain normal operation. Often work stations contain individual UPS backup to keep computers powered for a short amount time.

EPA Regulations for Emergency Generators

The exhaust of a diesel engine contains by products from combustion. For environmental safety, the below emissions are monitored:

• Nitrogen Oxide (NOx) – Occurs naturally as a result of bacterial process, biological growth, decay, lightning, forest fires and burning of fossil fuels. Colorless non-toxic gas (referred to as laughing gas). 
• Hydrocarbons (HC) – Organic chemical compounds that consist entirely of carbon and hydrogen. They range from simple molecules such as methane to polymers such as polystyrene.
• Carbon Monoxide (CO) – Colorless, odorless, toxic gas produced from incomplete burning of fossil fuels.
• Particulate Matter (PM) – The sum of all solid and liquid particles suspended in the air.

When selecting a generator set, an important consideration is application for the following reasons:

• Emergency Generator Applications – Do not have to maintain any emissions requirements for the below instances:


For more information on EPA regulations: Emissions for Standby and Emergency Generators.

Diesel Service and Supply

Diesel Service and Supply sells generators to facilities, including data centers, that require uninterrupted power supplies. We also purchase used industrial power generators and de-install and decommission generators  when a customer desires to upgrade an existing system.



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