||Commissioning in an Operational Datacenter
The 108,000 ft2 datacenter was originally built in the 1990's with a 72,000 ft2 raised floor area at a density of 100 Watts/ft2. The current owner purchased it several years ago and immediate business needs forced the owner to fill the datacenter to its design capacity. As the datacenter approached capacity in its original configuration, the present owner was faced with the option of using an additional site or rebuilding this site to accommodate anticipated future growth.
The owner undertook to expand this working datacenter in place to meet its immediate and future needs.Â The general design concept was to upgrade 36,000 ft2 of the datacenter's raised floor from 100 watts/ft2 to 220 watts/ft2.Â This would give the datacenter 8 MW total connected UPS load.Â
Electrically the design called for a 5 buss distribution system in an N+1 configuration.Â Mechanically, the design called for an N+1 configuration, no interruption to the operation of the datacenter during transfer from an air cooled to a water cooled mechanical system, and no change to the existing server cabinet size, load or the layout of the server rows.Â
CDCDG was retained by the owner to commission the upgraded datacenter. This work was done while the datacenter was completely operational; in fact, the commissioning work was woven into datacenter expansion efforts.
That is to say, as parts of the datacenter were upgraded, CDCDG was called on to test and certify those parts so that the owner could put them online to support business growth. This required significant flexibility on the part of CDCDG, including the departure from a classic commissioning effort.
The work scope for CDCDG included review and comment on the basis of design and Owner's Project Requirements, review of Pre-Functional Test scripts, Factory Witness Testing of selected equipment, development and execution of Functional Test Scripts, and development and execution of a modified Integrated Systems Test. While these are all steps included in classical commissioning efforts, CDCDG had to adapt them to the owner's rigorous schedule for increasing the datacenter's capacity for processing business transactions.
|The existing Electrical System was substantially increased with a completely new 21 KV incoming service coming from PG & E, the local utility. The emergency electrical power system was completely replaced and increased in capacity. Five (5) generators each of 2MW was installed and linked with paralleling switchgear, along with the supporting UPS System.
The existing air-cooled mechanical air-conditioning system was replaced with a water cooled system. The cornerstone of the new system was a five (5) chiller system installed in a modular fashion, so that the existing air-cooled system was gradually phased out while the new water cooled system was phased in. Each Trane chiller is 900 Ton capacity as required to support the ultimate loading expected.
Air distribution was accomplished with Stulz Computer Room Air Conditioning Units and Liebert XDP and XDV systems. The XD systems were be required because of the heat load density gradually being added to the datacenter.
The startup of the Mechanical System was particularly challenging, requiring additional temporary AC systems to cover "hot spots" created as the air-cooled system was dismantled and replaced with the water cooled system. The XD System, originally designed to serve rows of servers with similar heat loads, has had to be redesigned to cope with rows of servers that have significantly different loading patterns that vary over time.
The changes to the controls that handle Electrical and Mechanical Systems had to be integrated into the existing building control system.
As noted above, CDCDG reviewed the Design Basis, and the Owner's Project Requirements. Part of the challenge for this project was the fact that some of each had to change as the project progressed.
FACTORY WITNESS TESTING
CDCDG has also attended Factory Witness Testing. Unique to this project for instance, CDCDG attended the Factory Witness Testing of the individual Chillers, and then attended the Factory Witness Testing of the Modular Chilled Water System. The Modular Chilled Water System was built out at the Modular System Factory of Systecon, hooked up to Chilled and Condenser Water Systems at the factory and tested for parameters of operation. A key benefit of this testing was the ability of the Modular System Control System Supplier and the Building Management Control System Supplier to work out interface issues, so that installation at the site was virtually seamless.
LEVEL IV - FUNCTIONAL TESTING
Functional Testing Scripts for Level IV testing were created by CDCDG, reviewed by the Owner and the Contractors and approved for testing as would happen for a classic Commissioning project. In this case, the individual components could be tested against conditions in the field using Load Banks where necessary to simulate Design Conditions.
Flexibility was required to allow the operating datacenter to continue production while the testing was being conducted. This limited some of the Functional Testing Scope; educated simulations were sometimes required.
This has required that systems be partially tested, sometimes more than once to ensure proper operation. This has required that CDCDG provide its services in a flexible manner while maintaining their professional standards.
LEVEL V - INTEGRATED SYSTEM TESTING
Level V testing, the classic "pull the plug" test could not be performed for the total datacenter; the operating portions of the datacenter were off limits, so transferring power from utility to generator and return was necessarily restricted in scope, again requiring educated simulations in some cases. For instance, all the chillers could not run at load at once; there was not enough load to test all the generators at one time, and there were other situations.
The Owner was pleased with the segregated testing schemes, and their outcomes. The datacenter has continued to operate successfully during this testing period which will extend well into 2011.