It’s not as simple as just choosing a new brand of thermal fuses with an identical rated functioning temperature. In fact, out of an abundance of caution, our thermal fuse company strongly recommends performance testing, even if your thermal cutoffs supplier undergoes a part number alteration or a manufacturing location move.
Technical Questions: Choosing a New Thermal Fuse Source
First, the most important questions to ask are the basic technical specifications of the specific fuse in question. What is the rated voltage? What is the official rated functioning temperature?
While it’s crucial to always refer to the official manufacturer’s specifications for the answers to these technical questions, it’s just as important not to take these numbers at face value. For instance, the fuse’s rated voltage is tested for voltage levels a minimum of 15% above the nominal rating, while the rated opening temperature must operate at precisely the nominal rating. That’s why performance testing is so important when choosing a new fuse for your designs.
It’s also important to consider the ambient operating temperature of the device. In most cases, we recommend that your application run at least 20 degrees Celsius below the trip point of the fuse. Not only that, but temperature gradients can cause pellet type fuses in particular to bend or warp, degrading their integrity over time. (For further depth on this factor of pellet aging, we recommend reviewing U.L. Standard 1020.)
What about deciding between eutectic and pellet type TCOs? Most people use pellet type fuses for high-current applications, while eutectic TCOs are favored for low current applications. It’s also important to remember that some brands of axial cutoffs are extremely vulnerable to improper bending of the lead wires during installation, which is when we recommend SEFUSE brand fuses. SEFUSE brand TCOs are designed so that the epoxy resin seal won’t crack so easily.
In addition to technical considerations, financial pressures often motivate the switch between cutoffs. We know that many companies are feeling pinched in 2016. Thanks to tough overseas competition and recession-based declines, U.S. electrical equipment manufacturing grew by a mere .4% between 2010 and 2015. More recently, manufacturing as a whole has been going through a bit of a slump. And with U.S.-based manufacturers paying an average of 20% higher structural costs compared to global competition, there’s a high incentive to cut costs by any means necessary.
Even so, the risks of working with an unreliable or suspect thermal fuse company far outweigh the minimal cost savings. That’s why when deciding which thermal cutoffs to use in your designs, it’s important to contract exclusively with an authorized distributor working with a respected thermal fuse company. We proudly sell Elcut series thermal cutoffs and SEFUSE brand SF-E and SF-R series thermal fuses.