Mersen M085249 - Square Body High-Speed Fuse Protistor® Size 122 gR 750VDC IEC 315A With Striker Flush ends metric threads
Mersen

M085249

Alternate Item Number: D122GC75V315TF


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Specification Sheet

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Overview

The Mersen M085249 Protistor® Size 122 gR is a high-speed fuse-link designed for critical DC railway protection. Engineered for ultra-fast fault interruption, this fuse-link operates at 750VDC (IEC) with a continuous current rating of 315A. It provides exceptional short-circuit protection, featuring a pre-arcing I²t of 11.8 kA²s and a clearing I²t of 69 kA²s at rated voltage, minimizing damage to sensitive semiconductor components. The square body design incorporates flush metric threads for direct mounting in compact enclosures. An integrated striker offers visual and mechanical indication of fuse operation, facilitating rapid fault diagnosis. With a rated breaking capacity of 150kA, the M085249 exceeds typical industrial requirements and is suitable for traction power systems, DC link protection in inverters, and auxiliary converters. The fuse-link exhibits low watt losses, dissipating 66W at rated current, which reduces thermal stress on associated components and enhances service life. Compliant with IEC 60269-4 standards for semiconductor protection, this Protistor® variant is optimized for DC circuits with high di/dt conditions, offering superior performance in applications such as metro systems, locomotives, and stationary battery energy storage. The M085249 integrates seamlessly into existing protection schemes and is compatible with standard fuse holders for Size 122 gR. Mersen's DC semiconductor fuse-links are developed for elevated temperature operation, delivering lower I²t values to minimize component stress during short circuits while maintaining long-term reliability in harsh railway environments. SKU: M085249.
  • Mersen Protistor® Size 122 gR high-speed fuse-link
  • Rated 750VDC (IEC) and 315A continuous current
  • 11.8 kA²s pre-arcing I²t, 69 kA²s clearing I²t
  • 150kA rated breaking capacity
  • Square body with flush metric threads and integrated striker
  • 66W power dissipation at rated current for thermal efficiency
  • Designed for elevated temperature operation in DC railway systems
  • IEC 60269-4 compliant for semiconductor protection

Specifications

Amperage Rating
315 A
Application
Protection of inverters Protection of motor drives Protection of UPS systems Railway power and auxiliary circuits Similar 750VDC or less equipments
Brand Name
Mersen
Case
Ceramic
Connection
End Contact with Threaded Holes
Connection Type
Flush ends metric threads
Connection Type
metric threads
Current Rating
315 A
DC Voltage Rating
750 V
Mounting
Bolted
Mounting Type
Flush ends metric threads
Mounting Type
Flush ends
Series
Protistor®
Size
Size 122 gR
Size
Size 122
Size
5.16 x 2.32 x 2.48 in
Size
131 x 59 x 63 mm
Special Features
Multiple body sizes and terminals or blades combination Very low I²t Extremely fast acting Eliminate all overloads Excellent cycling capability
Standard
IEC 60269-4 Compliance
Sub Brand
Protistor®
Type
Square Body High-Speed Fuse-Links DC Protection
Type Of Indicators
Striker
Voltage Rating
750 V
Wattage
58 W
Package Dimensions (L x W x H)
5.16 in x 2.32 in x 2.48 in
Package Dimensions (L x W x H)
131 mm x 59 mm x 63 mm
Package Weight (Imperial)
3.153 lb
Package Weight (Metric)
1.430 kg
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9F61 Size B Clips 1.6in

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POWR-JAW clamps improve the contact between fuse and clip. The unnecessary heat from poor contact due to the loss of spring force in the clips can cause nuisance fuse opening and premature aging of surrounding components. High temperature phenolic resin knob designed for the most severe environments 7 sizes to provide effective coverage. Simple design makes installation easy.

LCC5

POWR-JAW clamps improve the contact between fuse and clip. The unnecessary heat from poor contact due to the loss of spring force in the clips can cause nuisance fuse opening and premature aging of surrounding components. High temperature phenolic resin knob designed for the most severe environments 7 sizes to provide effective coverage. Simple design makes installation easy.

Frequently Asked Questions about Mersen

What industries and applications are Mersen products used for?

Mersen products are used across diverse industrial sectors including solar power, electric vehicles, buildings/construction, industrial automation, power distribution, HVAC, elevators, telecommunications, and specialty manufacturing. Key application areas include circuit protection, surge protection, battery module protection, electrical safety systems, and power management for residential, commercial, and utility-scale installations.

What are the main product lines offered by Mersen?

Mersen offers five primary electrical power product lines: IEC and UL/CSA Fuses and Fusegear, Surge Protection, Low Voltage Disconnect Switches, Power Distribution Blocks, and Engineered Solutions. Their comprehensive range includes specialized components like high-speed fuses, modular fuse holders, surge arresters, and custom-engineered electrical protection systems for industrial and power management applications.

What are the key features of Mersen products?

Mersen products feature advanced electrical protection and power management solutions with key characteristics including finger-safe design, compact modularity, and high-performance safety features. Their product lines span electrical power components like fuses, surge protection, power distribution blocks, and specialized solutions for industrial, solar, and building applications. Critical features include UL/CSA approvals, high short-circuit current ratings, and innovative technologies like the Fuse Control™ program that minimize electrical risks and optimize system performance.

What environmental ratings do Mersen products have?

Mersen products meet rigorous environmental ratings across multiple standards, including UL 508A Type 1, 2, 3, 4, 4X, 12, and 13, CSA Type 1, 2, 3, 4, 4X, 12, and 13, and NEMA Type 1, 2, 3, 4, 4X, 12, and 13. They feature IEC 60529 IP66 protection, with enhanced UV inhibitors for outdoor weathering and operating temperatures ranging from -40°C to 130°C (-40°F to 266°F). These ratings ensure superior protection in wet, corrosive, and challenging industrial environments.

What accessories are available for Mersen products?

Mersen offers multiple accessories for their fuse blocks and systems, including safety pullers (DFC3M and DFC3LP), DIN-rail adapters (DRM), bus bars, auxiliary contacts, and specialized mounting hardware. Key accessories include the DFC3M safety puller for 1-1/2" x 13/32" midget or Class CC fuses, the DRM adapter for mounting 303 series fuse blocks on DIN-rail, and UltraSafe fuse module accessories like bus bars and auxiliary contacts that enable module interconnection and monitoring.

How are Mersen products typically installed?

Mersen products are typically installed in electrical distribution systems, control panels, and industrial automation environments using multiple mounting options. These include service entrance panel mounting, distribution panel installation, control panel DIN rail mounting, and custom engineered solutions like Fused Coordination Panelboards. Installation depends on the specific product type, such as fuses, surge protective devices, or switches, and is designed to provide electrical protection and circuit safety in various industrial and commercial applications.

What certifications and standards do Mersen products comply with?

Mersen products are certified to multiple international standards, including UL (Underwriters Laboratories), CSA (Canadian Standards Association), CCC (China Compulsory Certification), and EAC (Eurasian Conformity). Our products meet rigorous safety and performance standards for industrial applications across North America, China, Russia, and other global markets, ensuring compliance and reliability in electrical power and advanced materials solutions.

What technical support does Mersen offer?

Mersen provides comprehensive technical support through multiple channels, including technical experts located in your time zone who can assist with product selection, application guidance, and troubleshooting. Their Fuse Control™ program offers a free Fuse Inventory Audit & Analysis, and customers can access technical resources through their sales representatives and online platform ep.mersen.com.