Tacoma Power advises customers who use rotating equipment, such as generators and motors, to be aware of vulnerabilities that could impact their electrical system.

One such vulnerability, called an aurora, describes a narrow, but significant and exploitable gap in electrical protection that exists in the power grid.

Rotating equipment such as motors and generators normally spin in sync with the power grid. If that rotating equipment is brought onto or reconnected to the grid out of sync, damaging shaft and winding torques will result as the machine is instantaneously forced back into synchronization by the power of the grid.

An aurora can be described as an event that occurs when rotating equipment such as motors and generators spin out of sync with the power grid; it can occur accidentally or intentionally.

Vulnerable facilities could implement all traditional physical and cyber security best practices to protect their own breakers and electric switchgear from compromise yet still be vulnerable to an attach from outside their fence, if physical or cyber access were gained to a relevant upstream commercial substation breaker.

These documents, provided by the federal government, give more information about an aurora event and how to protect your system:

• Aurora overview
• IEEE References and Abstracts
• Accountability and Evaluation of Aggregate Effects of Through Faults On Power Transformers
• Transformer mechanical stress caused by external short-circuit: a time domain approach