Case Study PAGE 1

CASE STUDY Mission Critical/Power Quality

With Dollar General’s high growth rate they needed to expand their corporate data center. They also wanted to enhance the reliability of the electrical and mechanical infrastructure systems that support the data center’s operations by reconfiguring the systems for redundancy. As the prime consultant, Puckett Engineering was initially retained to evaluate the existing facility and electrical and mechanical systems to provide recommendations for supporting a data center expansion and adding Tier III/Tier IV redundancy to the systems. The study also needed to address the probable costs and to weigh the benefits versus costs. Puckett Engineering evaluated various options while utilizing as much of the existing infrastructure as possible. In addition, it was paramount that the upgrades be implemented so as not to require any interruptions to the data center’s operations. As a result of the study and collaboration with Dollar General’s personnel, Puckett Engineering’s solutions for expanding the data center and improving the reliability of the infrastructure systems in a cost effective manner included the following:

• Add a 500kW/625kVA emergency generator system and move the non-data center emergency power loads from the existing emergency generators to the new generator in order to free-up capacity on the current generators and distribution systems.

• Reconfigure the Normal and Emergency power distribution and loads for the two existing electrical services and two 800kW/1000kVA emergency generator systems in order to provide 2N redundant emergency power for the data center’s I.T. and mechanical loads.

• Add two additional UPS systems and additional Power Distribution Units (PDUs) in order to provide 2N redundancy in the UPS and PDU capacities up to 405kW/450kVA per side. UPS systems configured with maintenance bypass capabilities.

• Reconfigure the existing UPS power distribution and loads in order to provide 2N redundancy to the data center’s I.T. loads from the UPS systems and PDUs.

• Add additional Computer Room Air Conditioners (CRACs) in the data center for the expansion and for providing N+1 redundancy on each side of the data center.

• Reconfigure the power distribution and circuits to the CRACs in order to provide 2N redundant emergency power to the CRACs on each side of the data center.

• Surge protection for power distribution systems and the generator data and control circuits.

• Expansion of fire alarm system for the expanded data center and the two additional UPS rooms.

• Monitoring of all critical power system and air conditioning equipment via the Owner’s existing building management system.

• Cable tray system for data cabling in data center.

• Expanded under floor water detection system for data center expansion.

Dollar General Corporation Data Center Expansion and Infrastructure Redundancy Goodlettsville, TN

PROBLEM OR NEED

Data Center Expansion Needed redundancy in the critical infrastructure systems for improved reliability. PUCKETT SOLUTIONS

Comprehensive study to evaluate options and costs. 2N redundant utility transformers and switchgear 2N redundant emergency power systems. 2N redundant UPS systems. 2N redundant power to I.T. and mechanical loads. N+1 redundancy in data center air conditioning. Clean Agent Fire Extinguishing and Pre-action Sprinkler Systems. No downtime to data center

Year Completed: 2014 Contact: John Heisse Facilities Manager 615.855.4136

Case Study PAGE 2

CASE STUDY Mission Critical/Power Quality

• Expansion of the Owner’s Falcon monitoring system for monitoring power and other parameters of various feeder circuits and equipment and direct data connection to transfer switch power monitor.

• Complete re-design and replacement of the data center’s Emergency Power Off (EPO) system for code compliance, including features to avoid accidental activation, proof-testing without shutdown of loads, status indications, and monitoring for fault conditions.

• Circuit breaker coordination studies for selective coordination of devices.

• Identified all electrical and mechanical equipment and devices in order to readily ID equipment and devices and know where they feed from. In addition, color-coded nameplates were utilized to quickly identify whether a circuit is supplied from Side A or Side B of the redundant power distribution systems.

• Add an electrical room for housing new emergency power distribution equipment.

• Add spaces for the two additional UPS systems.

• Add additional structural steel for the existing floor structures for supporting the data center expansion and the UPS rooms.

• Concrete pad for new generator.

• Computer room air conditioners (CRACs) for the data center expansion area and UPS rooms.

• Expansion of the existing data center’s pre-action sprinkler system to cover the expanded area.

• Clean-agent fire extinguishing systems and pre-action sprinkler systems were provided for the two new UPS rooms.

• Special considerations were incorporated into the design for minimizing any negative impacts on the facility’s aesthetics.

• Design was implemented in phases on a fast-track basis.

• Special considerations and coordination during design and installation were included for maintaining daily operations and minimizing power interruptions during the work. All additions and modifications were achieved without any downtime to the data center’s operations.

• Construction administration services were also provided, including coordination, submittal reviews, site observations, extensive commissioning, and closeout documentation.

• Commissioning of generators, transfer switches, UPS systems and monitoring system, included load-bank testing, functional testing, battery capacity, thermal imaging, and simulating fault conditions. Adjustable settings for generator, transfer switches, and UPS systems were specified for compatibility with loads, controlling motor inrush, and to avoid nuisance transfers and retransfers.

Dollar General Data Center Expansion and Infrastructure Redundancy, continued