Mersen A070UD32KI550 Protistor Fuse, 550A 700V AC, Size 32 aR, High-Speed Square Body with KI Bolted Contacts - Pack of 3

The Mersen Protistor® A070UD32KI550 (Item Number K300194) is an ultra-fast acting square body fuse-link dedicated to the protection of power semiconductors. Rated at 550A and 700V AC, this Size 32 aR class fuse is engineered for high-power industrial environments such as traction sub-stations, large power rectifiers, and heavy-duty motor drives. It offers superior current limitation and very low I²t (clearance energy), ensuring the rapid isolation of faults to protect delicate electronic components like thyristors, GTOs, and IGBTs.

The fuse features a rugged ceramic body and silver-plated copper KI-style bolted contacts (Metric Bolted Studs), designed for low contact resistance and high durability under thermal cycling. The internal architecture consists of high-purity silver elements and refined silica sand for efficient arc quenching, providing a robust breaking capacity of 200kA. This unit includes a built-in K-type mechanical striker for positive trip indication, which can also be utilized to trigger an external microswitch for remote monitoring.

Technical Specifications

• Manufacturer: Mersen
• Catalog Number: A070UD32KI550
• Item Number: K300194
• Amperage Rating: 550A
• Voltage Rating: 700V AC (IEC / UL)
• Interrupting Rating (Breaking Capacity): 200kA at 700V AC
• Operating Class: aR (Ultra-Fast Acting)
• Product Size: 32
• Mounting Configuration: KI (Metric Bolted Studs)
• Indication System: Integrated Mechanical Striker (K-Type)
• Pre-arcing I²t: 51 kA²s
• Total Clearing I²t at Rated Voltage: 340 kA²s
• Power Dissipation at Rated Current: 90W
• Standards Compliance: IEC 60269-4, UL 248-13 Recognized, RoHS Compliant
• Quantity: Pack of 3