SINOFUSE RSZ307-3-RAZ 1500VDC High-Speed Fuse Selection Guide
The SINOFUSE RSZ307-3-RAZ series is a family of 1500VDC, Size 3, bolt-connected high-speed fuses designed for partial-range protection in high-power DC systems. The manufacturer series covers rated currents from 100A to 630A with a rated breaking capacity of 250kA.
SINOFUSE identifies the RSZ307-3-RAZ family as an aR protection category product for applications including high-voltage energy-storage cabinets and electrochemical energy-storage systems.
This guide summarizes the complete 12-model series, including rated current, pre-arcing I²t, total clearing I²t, power loss, installation requirements and replacement-selection considerations. Buyers looking for currently listed models can browse the SINOFUSE RSZ307-3-RAZ Collection .
RSZ307-3-RAZ Series Technical Overview
| Manufacturer | SINOFUSE |
| Series | RSZ307-3-RAZ |
| Product Type | High-Speed Bolt-Connected Fuse |
| Protection Category | aR — Partial-Range Semiconductor Protection |
| Rated Voltage | 1500VDC |
| Rated Current Range | 100A–630A |
| Breaking Capacity | 250kA |
| Time Constant | ≤5ms |
| Size | Size 3 |
| Approx. Weight | 2350 ±100g |
| Mounting | M8 bolt with spring washer |
| Recommended Torque | 11 ±1 N·m |
| Reference Standards | IEC 60269 / GB/T 13539 / UL 248 |
Complete RSZ307-3-RAZ Model Selection Table
The RSZ307-3-RAZ family includes twelve rated-current options. I²t and power-loss values increase substantially across the current range, so models should be selected by complete technical specification rather than current rating alone.
| Model | Current | Pre-Arcing I²t | Total I²t @ DC1500V | Power Loss |
|---|---|---|---|---|
| RSZ307-3-RAZ-100A1500V | 100A | 1,090 A²s | 5,000 A²s | 55W |
| RSZ307-3-RAZ-125A1500V | 125A | 1,940 A²s | 8,500 A²s | 65W |
| RSZ307-3-RAZ-160A1500V | 160A | 3,650 A²s | 15,800 A²s | 83W |
| RSZ307-3-RAZ-200A1500V | 200A | 5,900 A²s | 25,500 A²s | 100W |
| RSZ307-3-RAZ-250A1500V | 250A | 10,900 A²s | 47,000 A²s | 115W |
| RSZ307-3-RAZ-315A1500V | 315A | 20,500 A²s | 88,000 A²s | 133W |
| RSZ307-3-RAZ-350A1500V | 350A | 27,380 A²s | 120,000 A²s | 142W |
| RSZ307-3-RAZ-400A1500V | 400A | 39,400 A²s | 168,000 A²s | 155W |
| RSZ307-3-RAZ-450A1500V | 450A | 58,900 A²s | 277,500 A²s | 160W |
| RSZ307-3-RAZ-500A1500V | 500A | 79,100 A²s | 373,000 A²s | 180W |
| RSZ307-3-RAZ-550A1500V | 550A | 105,800 A²s | 500,000 A²s | 187W |
| RSZ307-3-RAZ-630A1500V | 630A | 158,000 A²s | 745,000 A²s | 214W |
What Does aR Mean?
The RSZ307-3-RAZ series is classified as aR. In IEC fuse terminology, an aR fuse is a partial-range high-speed fuse intended for semiconductor protection.
This means the fuse is optimized for rapid interruption of high fault currents and low fault-energy let-through. System designers should not assume that an aR fuse alone provides full-range overload protection; the complete protection architecture must be evaluated at system level.
Why I²t Matters in High-Power DC Protection
Rated current alone does not describe the behavior of a high-speed fuse during a short-circuit event.
Pre-arcing I²t represents the energy associated with the period before the fuse element begins interruption, while total clearing I²t represents the energy passed through the fuse during the complete interruption process.
Across the RSZ307-3-RAZ family, total I²t rises from 5,000 A²s at 100A to 745,000 A²s at 630A.
These differences are important when coordinating protection for power semiconductors, PCS equipment, DC buses and other high-energy electrical components.
Power Loss and Thermal Considerations
Power dissipation also increases with rated current. Manufacturer data ranges from 55W at 100A to 214W at 630A.
When selecting and installing a fuse, engineers should consider busbar design, connection resistance, enclosure temperature, ventilation, cooling and continuous loading together with the fuse power-loss value.
Energy Storage and High-Voltage DC Applications
SINOFUSE identifies high-voltage energy-storage cabinets and electrochemical energy-storage solutions as application scenarios for the RSZ307-3-RAZ family. Depending on the complete protection design, potential applications may include:
- Battery energy-storage systems
- High-voltage energy-storage cabinets
- PCS power-conversion systems
- 1500VDC bus protection
- Industrial power converters and inverters
- Power-semiconductor protection circuits
- High-current DC electrical systems
Final fuse selection should always be based on the prospective fault current, protected equipment, coordination requirements and complete system design.
Mechanical Installation
The RSZ307-3-RAZ series uses a Size 3 square-body construction with M8 bolted terminals.
- Mounting bolt: M8
- Recommended installation: bolt with spring washer
- Recommended tightening torque: 11 ±1 N·m
- Approximate fuse weight: 2350 ±100g
Mechanical dimensions and terminal alignment should be checked against the manufacturer drawing and the existing equipment before approving a replacement.
How to Select an RSZ307-3-RAZ Replacement
Before approving a replacement, verify:
- Complete RSZ307-3-RAZ part number
- Rated current
- 1500VDC system voltage
- aR protection requirement
- 250kA breaking capacity requirement
- Pre-arcing I²t
- Total clearing I²t
- Power loss
- Size 3 mechanical dimensions
- M8 terminal configuration
- Thermal and installation conditions
A fuse with the same current and voltage rating should not automatically be treated as equivalent if its protection category, I²t characteristics, breaking capacity or mechanical construction differ.
RSZ307-3-RAZ Frequently Asked Questions
What voltage is the RSZ307-3-RAZ series rated for?
The series is rated at 1500VDC.
What current ratings are available?
The manufacturer series includes 100A, 125A, 160A, 200A, 250A, 315A, 350A, 400A, 450A, 500A, 550A and 630A.
What is the breaking capacity?
The rated breaking capacity is 250kA.
What does aR mean on an RSZ307-3-RAZ fuse?
aR identifies a partial-range high-speed fuse intended primarily for semiconductor short-circuit protection.
Can two RSZ307-3-RAZ current ratings be substituted?
Not automatically. Current rating, I²t, power loss and system protection requirements must be reviewed before any substitution.
Can Apexon Supply source models not currently listed online?
Buyers can provide the exact manufacturer part number, required quantity, product-label photo and application information for sourcing review and quotation.
RSZ307-3-RAZ B2B Sourcing Support
Apexon Supply supports industrial buyers with:
- Exact RSZ307-3-RAZ MPN sourcing
- Manufacturer specification review
- I²t and power-loss verification
- Mechanical and installation review
- Product-label and photo checking
- RFQ and bulk quotation support
- Proforma invoice preparation
- International delivery coordination
For faster quotation, provide the complete part number, required quantity, product-label photo, and delivery country.
Browse RSZ307-3-RAZ Models | Browse All SINOFUSE Products
Independent Supplier Notice
Apexon Supply is an independent industrial parts sourcing supplier and is not presented as an authorized SINOFUSE distributor or representative. SINOFUSE trademarks, model numbers, product names and other identifiers belong to their respective owners and are used solely for product identification, technical reference and procurement purposes.