Bussmann 170M5448 Eaton series high speed square body fuse, 700V (UL), 690V (IEC), 800A, 100 kAIC, Other, Fuse, Class aR, Flush - 170M5448

Class aR is a partial-range semiconductor protection fuse. The 170M5448 is built for semiconductor protection, and its utilization category is aR, meaning it interrupts short circuit currents only. It does not provide overload protection across the full current range, so the drive, rectifier or converter it feeds still needs separate overload protection (electronic trip in the drive or a thermal overload device). If you need full-range protection including overload, you want a gR/gS type rather than aR.

Flush end contacts, square body. The 170M5448 mounts flush, meaning it bolts directly down onto flat bus or pad style contacts rather than plugging into a blade or clip style holder. If your existing base is built for a bladed (DIN blade) square body fuse, this one will not seat in it, and you need the flush contact version of the base or an adapter. Match the body form to the base before ordering.

Melting (pre-arc) I2t is 245,000 A2s. Total clearing I2t is 1,200,000 A2s at 1000 V and 1,550,000 A2s at 1250 V. To protect the semiconductor, the device I2t withstand rating from your SCR or diode datasheet must exceed the fuse total clearing I2t at your actual circuit voltage. Use the pre-arc figure for selective coordination against downstream fuses.

The part is Bussmann 170M5448, an 800 A square body high speed fuse with flush end contacts, 100 kAIC interrupting rating, Class aR. Order by that full number: the 170M family uses the trailing digits to distinguish body size, ampere rating and contact style, and an adjacent number will be a different body or a different current. Supplied in standard packaging.

It measures 92 mm deep by 163 mm wide by 60 mm high and weighs 818 g. That is a substantial square body fuse, so check the door depth and the spacing of your fuse base or disconnect before you commit, particularly if you are stacking three of them in a three phase arrangement.

Rated watt loss is 120 W at full load. Multiply that by the number of fuses in the enclosure (360 W for a three phase set) and add it to your cabinet heat load when sizing fan or air conditioner capacity. Running the fuse below its 800 A rating drops the dissipation, but for worst case thermal design use the 120 W figure.

It is IEC rated and CE marked, which covers the paperwork for an IEC built panel or a machine shipping into the EU. The square body high speed format with flush contacts is the standard IEC semiconductor fuse form factor, so it matches European drive and rectifier fuse bases rather than North American clip style holders.

The published rating on this fuse is AC. DC service on a high speed semiconductor fuse is a different rating with different time constant derating, so do not apply the AC figures to a DC link or battery circuit. For DC bus protection, specify a square body fuse that carries a published DC voltage and L/R time constant rating.

No. This one is supplied without insulated metal gripping lugs (IMGL), so the fuse body is handled directly. Plan on the circuit being isolated and verified dead before removal, and if your maintenance procedure calls for IMGL handling, specify an IMGL variant of the square body fuse instead.