In our last blog post, we explored the ways friction springs provide vital protection from devastating earthquakes. These damping components rely on tapered mating rings, which overlap under load and dissipate up to two-thirds of introduced energy. Recognizing the critical role of these friction springs, one Pacific Northwest utility has taken a proactive approach to protecting its facilities from the predicted “Big One.”
Let’s dive into this case example, which explores how seismic protection is possible without breaking the bank:
The Pacific Northwest—which has increasingly come under seismic scrutiny—is home to the Seattle Fault and Cascadia subduction zone. These areas have the potential to produce a 9-magnitude earthquake within the next 50 years.
A local utility recognized the devastating repercussions this “Big One” could have on its operation. Currently, the utility includes multiple hydroelectric generation facilities, several hundred miles of transmission lines and many substations. Its 700,000 customers include residential homes, hospitals and major industrial plants.
The Capacitor Bank Assembly
The company took several steps to upgrade its substation equipment. One of these modifications included installing friction springs on the capacitor bank—a tall, narrow, top-heavy structure that resembles a battery rack on stilts.
Because the friction springs operate under load, the company installed two springs on each leg, enabling the upper portion of the capacitor bank to provide the necessary preload. The capacitor bank then “floats” on the friction springs above the concrete base pad, allowing them to cycle and dissipate energy. An enclosure was also added around the friction springs to keep foreign materials away from the friction springs.
A downward load on the friction springs during an earthquake triggers the damping mechanism—compressing the inner rings and expanding the outer rings. This friction dissipates the damaging energy to protect and preserve equipment. When the load is removed, internal stresses reverse the action and restore the spring to its original shape.
A Cost-Effective Seismic Solution
Friction springs are now used on many substations throughout the Pacific Northwest as an effective way to protect utility equipment from earthquakes. Due to their cost-effective design, you can even add these components to seismically qualified equipment, such as circuit breakers, as an extra boost.
These upgrades ensure utility equipment last their full lifecycle. You’ll also avoid post-disaster downtime and equipment repairs—which, in the event of a 9-magnitude quake, can take over a year to complete.
To learn more about how friction springs can benefit your utility operation, visit our product page.