Techspan: Fusetek Medium Voltage “E” & “R” Rated Fuses
April 15, 2025
Fusetek MV “E” & “R” Rated Fuses: Robust & Effective Solutions
MV fuses are current and energy limiting fuses intended for the backup protection of medium voltage motor control. They are non-venting. MVR fuses have integral striker/indicators and have standardized dimensions compatible with today’s 5.5kV motor control gear.
MVR fuses are fully interchangeable with other manufacturers’ fuses of the same type and rating. MVR fuses feature a ‘field toughened’ element design which makes them less susceptible to mechanical damage during shipping and installation while also providing superior cycling characteristics.
Features
- Integral indicating pin
- Standard “R” Ratings
- Toughened element design
- Fully plated parts
Options
Standard fuses are clip-in design with 3” diameter barrels (18R – 36R are double barrel designs) and have an integral striker/indicator pin. Several options are available to make them compatible with other manufacturers’ specialized designs. Add suffixes to the part number as required. More than one option can be specified. All options are not available in some voltages.
Technical Data
Amp Rating
Each MVR fuse has both an assigned ‘R’ and amp rating. It is the ‘R’ rating of the fuse that governs the motor starting capability and coordination with the overload relays. To maintain the same capabilities, fuses should be replaced with matching ‘R’ ratings. On direct across the line starts, the necessity of passing the motor starting current results in a fuse selection with an assigned amp rating well above the nominal motor full load amps.
However, applications using reduced voltage starts, variable frequency drives or other methods to reduce the motor starting current, can result in a fuse rating with an amp rating too close to the motor F.L.A. As a check, the fuse’s assigned full load amp rating should be a minimum of 140% of the nominal full load amps of the motor.
“E” Rating MVE5 fuses have standard “E” rated characteristics.
Applications
