PureWave® Source-Transfer System Enhances Power Continuity for Data Center

To handle their expanding business, a major Midwestern insurance company built a satellite campus in a rural area about 10 miles from their downtown headquarters. The satellite campus houses a new data center, which is linked to the downtown data center that now serves as a back-up.

The continuity of electrical service on the 24.9-kV distribution line serving the new facility was of major concern.

What did they do?

After studying several options for enhancing service continuity—including a new transmission line and distribution substation—the local utility agreed to extend a 24.9-kV distribution line to the facility from another substation. The insurance company specified a split-bus S&C PureWave® Source-Transfer System to provide seamless transfer between the two sources. For additional redundancy, a customer-furnished generator and automatic transfer switch were installed on one of the distribution lines, to provide a third source of power in the event of an extended utility power outage.

Each distribution line serves approximately half of the campus load. If a voltage sag or outage occurs on either feeder, the system transfers the entire load to the other feeder in 2 to 4 milliseconds (about ¼ cycle), assuring continuous power to the facility.

Vault-Mounted Style 29-kV S&C Vista® Underground Distribution Switchgear, connected to the output bays of the source-transfer system, provides switching and overcurrent protection to downstream feeders. Vista gear was chosen because of its compact size and ease of application.

S&C’s Power Systems Services Division was contracted to oversee the field assembly and commissioning of the PureWave Source-Transfer System and Vista Underground Distribution Switchgear. PSS was also responsible for the foundation design and testing of the S&C products, as well as generator integration testing and training of the company’s maintenance personnel.

Results

Since 2003, the PureWave Source-Transfer System has operated about once a month. It has allowed the facility to avoid the impact of over 40 significant voltage sags. According to facility personnel, the equipment has performed flawlessly and load transfers between the two sources have been transparent to users. Since utility power has always been available, the data center UPS system has run much less frequently, extending the life of the batteries.