2.5kV and 4.8kV R-Rated Motor Protection Fuses, RA and RC Series
DENCO's 2.5kV (RA) and 4.8kV (RC) R-rated fuses give short-circuit protection to medium-voltage motors and motor controllers. The RA range covers 1R to 36R (35A to 650A) in a 10-7/8 in (276mm) body. The RC range covers 2R to 36R (70A to 650A) in a 15-7/8 in (403mm) body. Both carry a thermal striker.
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The two ranges share the R-rating rule printed in the catalog: an R-rated fuse melts in 15 to 35 seconds at a current equal to 100 times its R rating. They differ in length and test voltage. The 2.5kV RA fuses are tested to 100kA RMS asymmetrical and 65kA RMS symmetrical at 2750V. The 4.8kV RC fuses are tested to the same 100kA and 65kA figures at 5500V. The 4.8kV fuses are also available with a hookeye.
Each catalog number encodes the barrel prefix, the R size and the ampere rating, so RA1-6R170 is a 6R, 170A fuse. The table also prints a minimum interrupting rating for every size: 100A for the 1R up to 2900A for the 36R at 2.5kV, and 190A for the 2R up to 2810A for the 36R at 4.8kV. DENCO notes that these fuses can also be designed to customer specifications.
Specifications
| Parameter | Value |
|---|---|
| 2.5kV range (RA) | 1R to 36R, 35A to 650A |
| 2.5kV fuse length | 10-7/8 in (276mm) |
| 2.5kV interrupting rating | 100kA RMS asym / 65kA RMS sym at 2750V |
| 2.5kV minimum interrupting rating | 100A (1R) to 2900A (36R) |
| 4.8kV range (RC) | 2R to 36R, 70A to 650A |
| 4.8kV fuse length | 15-7/8 in (403mm) |
| 4.8kV interrupting rating | 100kA RMS asym / 65kA RMS sym at 5500V |
| 4.8kV minimum interrupting rating | 190A (2R) to 2810A (36R) |
| R sizes, 2.5kV | 1R, 2R, 3R, 4R, 5R, 6R, 9R, 12R, 18R, 24R, 36R |
| Melting characteristic | Melts in 15 to 35 s at 100 times the R rating |
Construction and options
- Thermal striker
- 4.8kV fuses also available with hookeye
- Three drawing figures (A, B, C) per voltage, by size
- Can be designed to customer specifications
Catalog numbers in this series
| Catalog no. | Availability | Last reviewed |
|---|---|---|
| RA1-1R35 | Active | 2026-08-27 |
| RA1-2R70 | Active | 2026-08-27 |
| RA1-3R100 | Active | 2026-08-27 |
| RA1-4R130 | Active | 2026-08-27 |
| RA1-5R150 | Active | 2026-08-27 |
| RA1-6R170 | Active | 2026-08-27 |
| RA2-9R200 | Active | 2026-08-27 |
| RA2-12R230 | Active | 2026-08-27 |
| RA3-18R390 | Active | 2026-08-27 |
| RA3-24R450 | Active | 2026-08-27 |
| RA3-36R650 | Active | 2026-08-27 |
| RC1-2R70 | Active | 2026-08-27 |
| RC1-3R100 | Active | 2026-08-27 |
| RC1-4R130 | Active | 2026-08-27 |
| RC1-5R150 | Active | 2026-08-27 |
| RC1-6R170 | Active | 2026-08-27 |
| RC1-9R200 | Active | 2026-08-27 |
| RC1-12R230 | Active | 2026-08-27 |
| RC2-18R390 | Active | 2026-08-27 |
| RC2-24R450 | Active | 2026-08-27 |
| RC3-36R650 | Active | 2026-08-27 |
Applications
- Short circuit protection of medium voltage motors and motor controllers
Curves and drawings
This series is on pp.53–56 of the January 2025 DENCO catalog. Access the catalog or ask for the drawing or curve you need.
Technical review
Specifications on this page are quoted from DENCO’s product catalog. Confirm any rating against DENCO engineering before specifying.
Related
- R-Rated Motor & Soft-Starter Fuses: the full family
- 7.2kV bolt-on R-rated motor fuses (RD)
- All fuse product families
- Cross-reference and discontinued replacement
Request a quote for 2.5kV and 4.8kV R-rated motor fuses (RA / RC)