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Bussmann 170M6309 Class aR High Speed Fuse, 550A
The Bussmann 170M6309 is a Class aR high speed fuse engineered for demanding DC power protection applications. Rated 550A RMS with a voltage rating of 1250 Vac (IEC) and 1300 Vac (UL), this fuse delivers a 200 kAIC interrupt rating for reliable short-circuit interruption. It is commonly applied in DC common bus systems, DC drives, power converters/rectifiers, and reduced voltage starters. The fuse is UL Recognized and IEC Rated, supporting dependable performance in critical industrial circuits.
Key Features
- Amperage/Current Rating: 550A RMS for high-capacity DC circuit protection.
- Voltage Rating: 1250 Vac (IEC) and 1300 Vac (UL) for use across international and North American systems.
- Interrupt Rating: 200 kAIC for dependable interruption of high fault currents.
- Fuse Class: Class aR high-speed fuse construction suited to semiconductor and DC drive protection.
- I2t Characteristics: Pre-Arc I2t of 19500 and Clearing I2t at 660V of 135000 for precise let-through coordination with upstream and downstream devices.
- Watt Losses: 100W.
- Body Style: Square body, French-style construction with Non Indicating fuse operation, sized for Type T/micro fuse indicator compatibility.
- Application Versatility: Suited for DC common bus, DC drives, power converters/rectifiers, and reduced voltage starters.
Certifications & Compliance
- UL Recognized
- IEC Rated
- CE Marked
- RoHS Compliant
Technical Specifications
- Amperage Rating: 550A
- Application: DC common bus, DC drives, power converters/rectifiers, reduced voltage starters
- Class: Class aR
- Clearing I2t: Clearing at 660V: 135000
- Current Rating: 550A RMS
- Fuse Indicator: Non Indicating
- Interrupt Rating: 200 kAIC
- Packaging Type: Standard
- Pre Arc I2t: 19500
- Voltage Rating: 1250 Vac (IEC), 1300 Vac (UL)
- Watt Losses: 100W
- Product Type: Square body, French style -E/ type T indicator for micro
- Product Length: 5.433 IN
- Product Details: Square body, French style -E/ type T indicator for micro
- Product Height: 2.087 IN
- Product Weight: 1.6456 LB
- Product Width: .315 IN
Typical Applications
- DC Common Bus Protection
- DC Drive Circuit Protection
- Power Converters and Rectifiers
- Reduced Voltage Starters
- Industrial Semiconductor Protection
Why Bussmann?
Bussmann fuses deliver dependable, code-compliant overcurrent protection for demanding industrial applications. With UL Recognized and IEC Rated construction, a 200 kAIC interrupt rating, and precisely engineered I2t characteristics, the 170M6309 provides the reliable performance electrical professionals expect from Bussmann for DC drive and power conversion circuits.
Manufacturer Resources
Product Specs
- Amperage Rating:
- 550A
- Class:
- Class aR
- Clearing I2t:
- Clearing at 660V: 135000
- Current Rating:
- 550A RMS
- Fuse Indicator:
- Non Indicating
- Interrupt Rating:
- 200 kAIC
- Packaging Type:
- Standard
- Pre Arc I2t:
- 19500
- Voltage Rating:
- 1250 Vac (IEC), 1300 Vac (UL)
- Watt Losses:
- 100W
- Product Group:
- Fuses
- Department:
- Electrical
- Product Subgroup:
- Other Fuses
- Product Type:
- Fuse
- Product Length:
- 5.433 IN
- Product Height:
- 2.087 IN
- Product Weight:
- 1.6456 LB
- Product Width:
- .315 IN
Bussmann 170M6309 – Frequently Asked Questions
1) Will a Bussmann 170M6309 fuse protect semiconductors in a DC drive, or do I need a different class?
Class aR is what you want for semiconductor and DC drive work. The 170M6309 is a Class aR high speed fuse rated 550A RMS, built to clear fast enough to protect diodes, SCRs and IGBT stacks in DC drives, power converters and rectifiers, DC common bus systems and reduced voltage starters. A standard Class J or RK5 branch fuse will not clear fast enough for that duty. Note aR is a partial-range fuse: it handles short circuit current, not sustained low-level overloads, so overload protection has to come from the drive or an upstream device.
2) What voltage can the Bussmann 170M6309 be applied at on a 480V or 600V industrial system?
Plenty of headroom. The 170M6309 carries 1300 Vac under UL and 1250 Vac under IEC, so it covers 480V and 600V industrial systems and the higher bus voltages found on large converters. Both ratings are published because it is UL Recognized and IEC Rated, which matters if you build panels shipping to both North America and Europe.
3) What I2t values do I use to coordinate the 170M6309 with the rest of the circuit?
Use 19,500 A2s pre-arc and 135,000 A2s clearing at 660V. Compare the clearing figure against the I2t withstand of the semiconductor you are protecting, and keep the pre-arc value above the I2t of any downstream fuse you want to stay selective with. Clearing I2t rises with applied voltage, so the 660V figure is the reference point, not a worst case at full 1300V.
4) How much heat does the 170M6309 put into the enclosure?
Budget 100W of watt loss per fuse at rated current. On a three-fuse set that is roughly 300W into the cabinet, which is real load on your enclosure cooling calculation. Terminals also need clean, torqued bus connections, since added contact resistance pushes body temperature up and can derate the fuse.
5) Does the Bussmann 170M6309 have a blown fuse indicator for a microswitch?
The fuse itself is non-indicating, so there is no built-in visual flag. The body is the square body French style built for a type T micro indicator, meaning the indicator and its microswitch are a separate item you add when you want remote blown fuse signaling back to the drive or PLC.
6) Is the Bussmann 170M6309 compliant for export panels?
It is UL Recognized, IEC Rated, CE Marked and RoHS Compliant, so it can be specified into panels destined for North American and European markets. UL Recognized means it is a component listing, evaluated for use inside equipment rather than as a standalone listed device.
7) What part number do I order to replace a blown 550A high speed fuse in a Bussmann square body holder?
Order Bussmann 170M6309. The 170M series number is the full identity of the fuse, covering the 550A rating, the Class aR characteristic and the square body French style mounting together. Substituting a different 170M number at the same amperage can change body size or the I2t curve, so match the number exactly when replacing one in a drive.
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Does the Bussmann 170M6309 come with a warranty?
Absolutely. The Bussmann 170M6309 is backed by a manufacturer’s warranty.
For full warranty terms, check the product documentation or Contact Us.
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