High-speed aR fuse with 350A rating, ceramic body, striker indication system, slotted silver-plated copper blades, rated for 690VAC IEC and 700VAC UL standards.
£140.88
The Mersen R300050 (A070UD31KI350) is a premium Protistor® Size 31 square body high-speed semiconductor fuse designed to provide ultra-fast protection for modern power conversion equipment. Featuring an aR ultra-fast operating characteristic, it is specifically engineered to protect diodes, thyristors, IGBTs and other semiconductor devices against damaging short-circuit currents.
Constructed using precision die-cut silver fuse elements embedded in solidified sand, the R300050 delivers exceptional current limitation, low let-through energy and a high interrupting capacity. Silver-plated contacts, non-magnetic hardware and an integrated striker indicator provide dependable long-term performance while simplifying maintenance and remote monitoring.
With a 350 A current rating, 690 V AC (IEC) and 700 V AC (UL) voltage ratings, this Protistor® fuse is ideally suited to industrial drives, UPS systems, power converters, renewable energy installations and other demanding semiconductor applications.
Protistor® semiconductor fuses are specifically developed to interrupt fault currents before expensive semiconductor devices can be damaged. Their exceptionally fast response and low let-through energy help improve equipment reliability, minimise maintenance costs and reduce costly production downtime.
The Size 31 Protistor® range is widely used throughout industrial automation, renewable energy systems, motor drives, UPS installations and power conversion equipment where dependable semiconductor protection is essential.
| Item number | R300050 |
|---|---|
| Catalogue No | A070UD31KI350 |
| Description | Square Body High-Speed Fuse Protistor® Size 31 aR 690VAC IEC 700VAC UL 350A With Striker Slotted Blades short |
| EAN/UPC Code | 3605340322743 |
| Rated voltage AC UL | 700 V |
| Rated voltage AC IEC | 690 V |
| Ampere Rating | 350 A |
| RoHS Compliant | Yes |
| AC or DC | AC |
| Speed/Characteristic | aR |
| Fuse Size | 31 |
| Mounting | Bolted |
| Clearing I2t At Rated Voltage | 61000 A²s |
| Melting I2t | 10300 A²s |
| AC Max I.R./Breaking Capacity | I1: 200 kA |
| Indication System | Yes |
| Indication System Type | Striker |
| Connection/Terminal Material | Silver-Plated Copper |
| Connection/Terminal Type | Slotted Blades |
| Product Width | 51 mm |
| Product Length | 129 mm |
| Product Height | 56.5 mm |
| Sell Pack Quantity | 3 EA |
| Sell Pack Weight | 1.203 kg |
| Sell Pack Width | 157 mm |
| Sell Pack Length | 166 mm |
| Sell Pack Height | 62 mm |
| Product group | Semiconductor Protection Fuses |
| Body/Insulating Material | Ceramic |
| Product Weight | 0.401 kg |
| Power Dissipation at Rated Current Value | 67 W |
| HS Code | 85361090 |
| Country of Manufacture | France |
The Mersen R300050 provides ultra-fast short-circuit protection for semiconductor devices including IGBTs, thyristors, diodes and other power electronic components.
The R300050 has a rated current of 350 A.
It is rated at 690 V AC (IEC) and 700 V AC (UL).
The aR classification identifies an ultra-fast semiconductor protection fuse intended to clear short-circuit faults while protecting sensitive semiconductor devices.
Yes. The R300050 incorporates an integrated striker indicator that can operate an optional field-mountable microswitch for remote indication.
Mersen Protistor® semiconductor fuses are trusted worldwide by OEMs, panel builders and industrial engineers to provide dependable protection for critical power electronic equipment operating in demanding industrial environments.
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LED Controls is a specialist distributor of factory automation and industrial controls, supplying OEMs, machine builders, panel builders and end users throughout the UK and worldwide. As a trusted UK distributor for many of the world’s leading automation manufacturers, we provide industrial control products, technical expertise and bespoke automation solutions backed by outstanding customer service.
2025 has been a big year for LED Controls, and our blog has expanded accordingly. We've covered a wide range of topics across industrial control and factory automation this year. From core technology explainers and new product releases to panel building best practice...
2025 has been a big year for LED Controls, and our blog has expanded accordingly. We've covered a wide range of topics across industrial control and factory automation this year. From core technology explainers and new product releases to panel building best practice...