FERRAZ SHAWMUT X300078 6.6URD33TTF0630

Mersen (Ferraz Shawmut) Protistor High-Speed Fuse X300078 Description This Mersen (formerly Ferraz Shawmut) Protistor fuse, model X300078, is an essential component for protecting power semiconductor devices. It is an extremely fast-acting (aR class) fuse designed to safeguard sensitive electronics such as diodes, thyristors, and IGBTs from the damaging effects of short-circuit events. With a rating of 630A and 700V AC, it is suitable for high-power industrial applications like variable speed drives, inverters, and rectifiers. Specifications Manufacturer: Mersen (Ferraz Shawmut) Product Line: Protistor Model Number: X300078 Voltage Rating: 660-700V AC Current Rating: 630A Characteristic: aR (Extremely Fast-Acting for Semiconductor Protection) Body Style: Square Body Indicator: Visual Trip Indicator (Red Dot) Label Info Brand: FERRAZ Series: PROTISTOR Type: X300078 Rating: 660-700V AC 630A Specification: 6.6 URD 33 TTF 0630 Standard: VDE 0636/23classe aR Resistance: 0.188 mOhm (at 35 deg C) Application This high-speed fuse is ideally used in power conversion equipment to protect against catastrophic failures due to short circuits. Common applications include AC/DC drives, UPS systems, soft starters, and power supplies. Country of Origin This product was manufactured in France. CO2 Impact By choosing this reused industrial part, you are helping to avoid the production of a new one, which saves approximately 48 kg of CO2. This saving is equivalent to the emissions from driving a car for 240 kilometers. Availability This is an obsolete item but is available from our stock. Limited quantities are available. Order now from profideals for expert support and fast delivery. FAQ What does the ‘aR’ characteristic mean? The ‘aR’ class denotes an extremely fast-acting fuse designed for short-circuit protection of semiconductor devices like diodes, thyristors, and IGBTs. It does not provide overload protection. Can I replace a ‘gG’ fuse with this ‘aR’ fuse? No, this is not recommended. A ‘gG’ fuse provides both overload and short-circuit protection (full range), while an ‘aR’ fuse only provides short-circuit protection (partial range). Using an ‘aR’ fuse where a ‘gG’ is required would leave the circuit unprotected against overloads. What is the purpose of the red dot indicator? The red dot is a visual trip indicator. When the fuse blows, a small pin is released which makes the red dot pop out. This allows for quick identification of a faulty fuse in a panel. It can also be used to actuate a microswitch for remote signaling. profideals is not an authorized distributor, reseller or representative of the products featured on this website. All product names, trademarks, brands and logos used on this site are the property of their respective owners. Last Update: Friday, March 13, 2026