Fusible Links
Fusible Links
Skills: AutoCAD, Arduino, Data Analysis, Waterjet Cutting
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About NER
About NER
The Northeastern Electric Racing Club is a student-run organization that builds all-electric, formula-style racecars from scratch to compete in Formula Hybrid + Electric and Formula SAE. NER is made up of three divisions: business, mechanical, and electrical.
Fusible Links
Fusible Links
To ensure the electric car can be operated safely, a current-interrupting safety mechanism is required in the event of excessive current flow. This is typically achieved using fuses or fusible links connected to the battery. For our design, we chose to develop custom fusible links tailored to the car's specific electrical and safety requirements.
Design
Design
The fusible link interface needed to have good contact with the battery while not overheating and blowing too early. Using AutoCAD, we prepared three designs consisting of a U shape with a quarter turn, half turn, and three three-quarter turn. Through initial testing, the three-quarter turn showed the most promise, having more contact than the others and lasting sufficient time before blowing.
Manufacturing
Manufacturing
We selected a copper-nickel alloy for the fusible link to leverage copper's electrical conductivity and nickel's mechanical durability. A sheet of the alloy was waterjet cut in a two-by-seven array to support various testing cycles.
Initial attempts at soldering the links were unsuccessful due to the high heat required, which led to oxidation and poor attachment. We experimented with a method of brazing using silver flux and a blow torch. This approach demanded precision and speed to achieve a reliable bond with minimal oxidation.
Testing Configuration
Testing Configuration
Two neighboring links would be brazed onto metal bars connected to the circuit. The circuit consists of two power supplies, 10 resistors in parallel to simulate current flow, and the fusible links. A thermocouple was set up to monitor the temperature of the fusible link to ensure it was meeting safety standards, and a phone was used to record the test.
An Arduino was used to log current and temperature data throughout the testing process. The total power in the circuit could not exceed 40 kW, and each fusible link was required to blow within a specific time interval. We completed dozens of testing cycles, refining our brazing technique and ensuring the setup met all documented safety requirements.
and the Scruntineers' Award for overall preparedness
and the Scruntineers' Award for overall preparedness
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