Mersen AJT400ID Fuse AJT - Class J - Time-delay 600VAC 400VDC 400A Blade SmartSpot® Amp-Trap 2000®
Alternate Item Number: AJT400ID
UPC: 782001518417
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Contact for Pricing
Call +1 (262) 252-1600 (toll-free 877-268-3700) or email [email protected] for pricing and availability.
Overview
- 400A rated Class J time-delay fuse for 600V AC / 400V DC applications
- SmartSpot® visual indicator for clear operational status
- Compact design saves up to 50% mounting space vs. Class RK fuses
- Time-delay characteristics prevent nuisance tripping from inrush currents
- Low I²t and controlled arc voltage minimize component damage during faults
Specifications
Connection Type | Blade |
Current Rating | 400A |
Nema Rating | Class J |
Series | Amp-Trap 2000 |
Voltage Rating | 600VAC/400VDC |
Package Dimensions (L x W x H) | 7.13 in x 2.12 in x 2.12 in |
Package Dimensions (L x W x H) | 181.102 mm x 53.975 mm x 53.975 mm |
Package Weight (Imperial) | 1.7900 lb |
Package Weight (Metric) | 0.8120 kg |

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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.Frequently Asked Questions
What voltage ratings does the AJT400ID support?
The AJT400ID operates at 600 volts AC or 400 volts DC, as specified in the Mersen datasheet.
Is the AJT400ID suitable for motor protection?
Yes, the time-delay characteristics are calibrated to handle motor inrush currents without nuisance tripping.
Does the AJT400ID have an indicator for blown fuses?
Yes, the SmartSpot® visual open fuse indicator provides clear status indication when the fuse is blown.
What is the mounting type for the AJT400ID?
The AJT400ID uses blade-style mounting, compatible with standard Class J fuse holders.
What is the I²t value for the AJT400ID?
The AJT400ID features low I²t to minimize damage to protected components during short circuits.
What applications is the AJT400ID designed for?
The AJT400ID is designed for main, feeder, and branch circuit protection in industrial applications, including motors and transformers.
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.








