Should FMs Add a Second Utility Feed For Added Backup Power?
Fourth part of a four-part article on best practices for adding power in data centers.
Should facility managers consider bringing in a second utility feed to provide additional backup power capacity? According to Mark Evanko, Bruns-Pak, it is better for smaller operations to add emergency generators for additional backup power. A second utility source, either from the same power company — which would use a different substation — or a second utility company can be expensive. Nonetheless, for large, mission critical data centers, in which an hour of downtime can result in a multimillion dollar loss, bringing in additional power from a utility may be the best option, Evanko says.
When adding power in this way, "the utility needs to know how much more power you want to use," says Rajan Battish, RTKL. "The company may not have enough power and might have to transfer circuit capacity upstream of the facility. They will need to know if the circuit feeders have enough capacity and if the actual physical capacity is available at the substation or if they need to re-route power.
"If they reroute power or increase substation capacity, they will affect your short circuits at the facility level," Battish says. “You must make sure other components are not undersized as a result of the short circuit increases.” Electrical equipment designed for a certain amount of fault current (short circuiting) must be able to handle the additional power. Equipment designed for a few hundred amps, for example, can only handle 1,000 amps for 50 milliseconds. For that reason "everything must be properly sized," Battish says.