Article Courtesy of Daniel Cleveland, Technical Services Representative

Independent test research shows that silver-based fuse elements ranked number one against three competing tin-based element designs.

Have you ever had to roll a truck because a cutout fuse link operated causing an outage for no apparent reason? What if you could stop these unnecessary outages? Well, the latest research says you can.

Past tests have shown that tin-based fuse elements will change in varied degrees due to exposure to repeated shots near the manufacturer’s published melt curve (OMPC). Technical experts say partial melting of a fuse can lead to a fuse operating with no fault being present, termed as “sneak-out” by some line workers. 

Every utility’s O&M budget takes a hit due to nuisance fuse-link operations. From the CEO to the supervisor to the engineer, knows how expensive it is to roll a truck. From labor costs to fuel and maintenance, to the cost of lost productivity, when a truck is dispatched to replace a fuse for an known reason; no matter from which budget line item you pinched for the money, you are shoveling hard dollars into a needless and preventable expense.

So, let’s conservatively say, in a hypothetical scenario, that all your truck rolls in a given year costs on average about 500 dollars and that a reasonably priced fuse (T-25 or less) is normally five dollars. Now, imagine if only 3% or 30 fuses (30 out of 1,000 installed fuse links) nuisance-operates every year for no apparent reason; that’s 15,000 dollars being squandered from an already stretched budget, being wasted to hunt for phantom faults. This would be like buying 30 fuses every year at a price of 15,150 dollars (truck rolls + new fuses)! However, you can turn things around quickly from burning that money and limited labor resources to saving it. Ask yourself this: “What’s in the fuses that am I buying?”

The key to improvement lies in mitigating nuisance operations. This can be done by using superior performing silver-fuse links, which scientific testing shows are not susceptible to sudden-death phenomena after multiple applications near its minimum melt curve.   

In a 2013 test report, a trusted independent research institution in the United States, conducted a controlled experiment to determine in part whether modern expulsion fuses are susceptible to damage when exposed repeatedly to currents near their published minimum melt curve.

Four 25-T fuse links, “out of the box”, from four different manufacturers were stress tested at 93 percent of their published minimum melt curve (610 amps and 0.1 second) to determine their damageability and melt performance. (Note that all manufacturers have the same published T-curves, even though the manufacturers have different designs.)

Summary Results:

In first place is manufacturer four, with all fuses passing all 30 shots each; an additional six fuses were tested and passed. Note that two sacrificial fuses were used to complete both test setup circuits for manufacturer four, and those fuses survived as well. 

Note: sacrificial fuses are not counted against the manufacturer, if failed. This does not affect the final rankings.

Manufacturers one and three tied for second place, having only one fuse pass. Their sacrificial fuses did not survive.

Manufacturer two is ranked last with none passing. The sacrificial fuse did not survive.

It is reasonable to conclude that fuse links with silver elements can reliably handle continuous load currents at 93 percent of the minimum melting current without sudden-death occurring, eliminating nuisance fuse operations, and providing permanently accurate time-current characteristics. This then reduces unnecessary outages by improving your system coordination and reliability.

Switching from tin to silver-based fuse links can be easily achieved without the headache or hassle of a large capital expenditure or a time-consuming engineering study. Silver fuse link manufacturers publish cross-reference guides so that you can seamlessly purchase silver fuse link part numbers in place of your tin links to begin to save and reduce unnecessary truck rolls immediately (the sooner fuses are deployed, the sooner you can begin saving money). Contact your Gresco representative to obtain a silver fuse link cross-reference guide.

* the 1984 Ontario Hydro Research report