Electrical Hot Spot                      

                      Typical Electrical Assembly

Technical White Paper Download

Electrical connections are often made up of materials that have various coefficients of thermal expansion. Additionally, the joint materials also carry more current than the bolts. This causes the joint to heat up more than the bolts. The resultant differential thermal expansion (DTE) results in an increase in bolt load, possibly causing the joint components to yield. During each thermal cycle, the bolt load may be reduced.

In addition, electrical connections may loosen over time due to vibration or embedment relaxation, which is caused by microscopic high points on both the threads and mating surfaces.

As bolt load is reduced, electrical joint resistance increases or causes heat or hot spots. This can result in even higher resistance and the product of which can be a catastrophic failure.

Solon Belleville Springs: Maintain Bolt Preload

Solon® Belleville Springs counteract the effects of differential thermal expansion by maintaining sufficient load on bolted electrical connections to prevent hot spots during and after temperature cycles. After yield and relaxation of joint components, a Belleville spring maintains a consistent, sufficient load on the bolted joint.

Belleville’s are used on electrical connections when the components of the connection are made of dissimilar (AL7CU or AL9CU) and similar materials because they maintain the bolt preload even during differential thermal expansion.

Properly used Solon Belleville Springs can reduce the loss of preload by a factor of 5X or more and greatly reduce the opportunity for failure.

Download the White Paper, Maintain Bolt Preload on Electrical Connections Using Belleville Springs

Download our technical white paper, Maintain Bolt Preload on Electrical Connections Using Belleville Springs for a deep-dive analysis on a bus conductor connection using Solon Belleville Springs.

Additional Resources for Electrical ApplicationsContact Us