Mersen D70QS300-4 D70QS Series High-Speed DC Fuse, 700VDC, 300A aR 20kA IR, 4.34in Round Body - Pack of 5

Overview: The Mersen D70QS300-4 is a North American style round-body high-speed semiconductor fuse from the D70QS Series, rated 300 A at 700 VDC with L/R ≤1 ms and a 20 kA interrupting rating. This item is sold as a pack of 5 units. It provides rapid short-circuit protection with low I²t and low watts loss for DC power electronics, ESS/BDU, and UPS/inverter applications.

Key Features:

• 700 VDC rating; L/R ≤1 ms time constant
• High interrupting rating: 20 kA DC IR
• aR characteristic for semiconductor short-circuit protection
• Lower I²t performance and low watts losses
• Superior cycling capability; vibration resistant design
• UL Recognized (UL File E60314); REACH/RoHS compliant

Technical Specifications:

• Ratings: 300 A, 700 VDC, L/R ≤1 ms, 20 kA IR
• Power dissipation (at 0.5 × In): 8.8 W
• Minimum Breaking Capacity (MBC) at 700 VDC: 1580 A; maximum time to clear MBC: 140 ms
• Dimensions (D70QS 225–400 frame): A=4.34 in (110 mm), B=1.50 in (38.1 mm), C=2.09 in (53.1 mm), D=3.41 in (86.6 mm), E=2.78 in (70.6 mm), F=0.41 in (10.4 mm), G=1.00 in (25.4 mm), H=0.25 in (6.4 mm)
• Weight: 0.26 kg per fuse
• Mounting/accessories: compatible with P243C fuse blocks (D70QS 225–600 A) and 1SC/1MSC modular fuse blocks (e.g., 1SC250/1SCM8 up to 400 A; 1SC375 for higher frames)

Applications:

• Energy Storage Systems (ESS) and Battery Disconnect Units (BDU)
• Battery charging and management systems
• DC fast‑charging stations and DC grids
• Backup protection for DC relays/disconnectors/switches
• UPS/inverters up to 700 VDC