Usage characteristics of Bussmann fuse

Bussmann plastic encapsulated square fuse and round fuse tube are carefully manufactured to ensure that every product shipped from the factory is qualified. The Bussmann fuse products have insulation, explosion-proof functions, and the highest flame retardant level is VO. / 350V) on power products. Voltage: 125V ~ 350V, current: 50MA ~ 15A.

   Electrical characteristics of Bussmann plastic encapsulated square fuse and round fuse tube:

1. Experimental conditions:
All test environment temperature is 25 ± 5 ℃.
2. Breaking capacity:
The fuse and fuse tube bear the breaking capacity: under 250V AC power supply, 35A or 10 times the rated current is larger.
3. Temperature rise test:
Pass 1.5 times of rated current for 15 minutes, then increase 0.1 times of rated current every 15 minutes. It is measured that the temperature rise of any part when the fuse link is broken shall not exceed 135 ℃, and the ambient temperature is 25 ± 5 ℃.

Where the plastic-encapsulated family fits

Plastic-encapsulated square-body and round-tube fuses cover the 125 V to 350 V, 50 mA to 15 A range. That is the low-voltage, low-current end of the range, which is where the application is usually protecting a printed circuit board, a small power supply or an instrument rather than a distribution feeder. The V-0 flame rating and the encapsulated body matter in that context because the fuse sits inside equipment where a ruptured element must not eject material onto neighbouring components.

Electrical characteristics of the plastic-encapsulated range

The breaking capacity is the limit that matters

A breaking capacity of 35 A, or ten times the rated current, whichever is larger, is adequate for a board fed from a small transformer or a linear supply. It is not adequate on the input of a switch-mode supply fed from a low-impedance mains circuit, where the prospective fault current can be several hundred amps. In that case the fuse must be backed by an upstream device that limits the fault current below the fuse's breaking capacity, or a higher-capacity family must be used.

Derating, and why the 25 °C test ambient matters

The ratings in the table are established at 25 ± 5 °C. A fuse carrying current inside an enclosure runs hotter than the ambient, and its element is already closer to melting than the nameplate suggests. Standard practice is to derate to roughly 75% of rated current at 40 °C enclosure temperature and to check the actual thermal environment rather than assuming the panel stays near room temperature. A fuse that opens repeatedly at what looks like rated current is usually a thermal problem rather than a fault.