Surviving data center lightning strikes


Data Center Knowledge reported this week that lightning knocked out major cloud computing data centers in the Dublin area.

Chris Brown, Uptime Institute Professional Services consultant offered some advice on how to protect your company’s data center from lightning strikes:

A near lightning strike is very difficult to protect against. Many items designed for protection against lightning strikes don’t handle large near strikes well. So it is important to have that in mind when designing a system.

Good lightning protection and a good facility grounding system are necessities. But because lighting protection and surge suppression are not foolproof, it’s important to design the system itself to provide some resiliency.

The story suggested multiple engine-generators sharing a single bus requiring the units to be synchronized. In such situations, it is typical to have engine-generator paralleling switchgear isolated from the incoming utility feeder. The engine-generator paralleling switchgear is used to synchronize the generators then connect that power to the individual substations. In this arrangement, the switchgear, bus, and controls are separated from the incoming utility. The controls are powered either via a UPS or station batteries.

Either way a lightning strike would typically destroy a double conversion on-line UPS or rectifier of a station battery system, instead of allowing energy to propagate through to the controls, providing protection.

Typically the only connection between the substation and the paralleling switchgear is control wiring (phase signals for closed transition switching and dry contacts for utility loss and circuit breaker positioning). With the isolation, the generators are allowed to synchronize to the bus and connect to the substations via closed transitions.

But if the controls in the substations were destroyed it is possible the system would not automatically connect the available generator power to the substations. This would require trained personnel to manually open the utility circuit breaker and close the generator breaker. But not nearly as difficult or hazardous as manually paralleling engine-generators on the same bus. So it is important to have trained personnel on site 24×7 for mission critical facilities.

In summary, near lightning strikes are difficult to protect against. So a full approach of grounding, lightning protection systems, surge and transient protection, system topology, and personnel are key to helping ensure your data center survives a near lightning strike.

Posted by mstansberry on 09-08-2011
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