Dongfa Intelligent supplies the 12kV Load Break Switch-Fuse Combination Unit, which integrates load switching and fuse protection in a single device. It covers FZN25-12D/T630-20 and FZRN25-12D/T125-31.5 configurations, supporting 125A/630A rated current, 31.5kA short-circuit breaking, and 1250kVA no-load transformer breaking. The unit is used in 12kV medium-voltage distribution systems for transformer protection and industrial distribution.
The 12kV Load Break Switch-Fuse Combination Unit combines the load break switch and high-voltage fuse in one device. The load switch handles normal load current switching and loop breaking, while the fuse provides short-circuit fault interruption. This integrated design reduces cabinet components and wiring complexity compared with separate circuit breaker and relay protection solutions.
FZN25-12D/T630-20 is suitable for 630A load scenarios with 20kA 4s thermal stability and 50kA peak stability. FZRN25-12D/T125-31.5 is suitable for 125A load scenarios with 31.5kA short-circuit breaking current, 870A rated transfer current, and SDLAJ-12/SFLAJ-12 fuses. Selection depends on load current and short-circuit level.
The unit includes an earthing switch with 50kA rated peak stability current and 20kA 2s thermal stability current. It provides safety grounding during maintenance and supports five-prevention interlocking requirements. Auxiliary circuit voltage options include AC/DC 110V and 220V.
The product is manufactured according to applicable GB standards and IEC 62271 requirements. Quality management systems include ISO 9001, ISO 14001, and ISO 45001 certifications. Testing capability is CNAS/IAF recognized.
Standard products support a minimum order quantity of 1 unit with a lead time of 7-15 working days. Customized configurations require 15-30 working days depending on technical requirements. Each unit undergoes resistance test, mechanical operation test, withstand voltage test, and vacuum degree inspection before shipment.
The 12kV Load Break Switch-Fuse Combination Unit combines a load break switch and a high-voltage fuse. The load switch manages normal load current switching and loop breaking, while the fuse provides fast short-circuit fault interruption. This provides both normal operation and short-circuit protection functions. Compared with circuit breaker solutions, the combination unit has a simpler structure and is suitable for small- to medium capacity distribution.
FZN25-12D/T630-20 is designed for 630A load scenarios, with 630A rated active load breaking current, 20kA 4s thermal stability, and 50kA peak stability. FZRN25-12D/T125-31.5 is designed for 125A load scenarios, with 31.5kA rated short-circuit breaking current, 870A rated transfer current, and SDLAJ-12/SFLAJ-12 fuses. Selection is based on load current and short-circuit level.
An earthing switch is integrated into the unit with 50kA rated peak stability current and 20kA 2s thermal stability current. It provides reliable safety grounding during maintenance and meets five-prevention requirements. Auxiliary circuit voltage options include AC/DC 110V and 220V, adapting to different switchgear control power supplies.
| Parameter | FZN25-12D/T630-20 | FZRN25-12D/T125-31.5 |
| Rated Voltage | 12kV | 12kV |
| Rated Frequency | 50Hz | 50Hz |
| Rated Current | 630A | 125A |
| Power-Frequency Withstand (Interrupter Gap) | 30kV | 30kV |
| Power-Frequency Withstand (Phase/Earth) | 42kV | 42kV |
| Power-Frequency Withstand (Isolation Gap) | 48kV | 48kV |
| Lightning Impulse Withstand (Phase/Earth) | 75kV | 75kV |
| Lightning Impulse Withstand (Isolation Gap) | 85kV | 85kV |
| Rated Peak Stability Current | 50kA | — |
| 4s Thermal Stability Current | 20kA | — |
| Rated Active Load Breaking Current | 630A | 125A |
| Rated Loop Breaking Current | 630A | 125A |
| Rated Cable-Charging Breaking Current | 10A | 10A |
| No-Load Transformer Breaking Capacity | 1250kVA | 1250kVA |
| Rated Short-Circuit Breaking Current | — | 31.5kA |
| Rated Transfer Current | — | 870A |
| Fuse Model | — | SDLAJ-12 / SFLAJ-12 |
| Striker Output Energy | — | 2-5J (Medium) |
| Rated Short-Circuit Making Current | 50kA | — |
| Parameter | FZN25-12D/T630-20 | FZRN25-12D/T125-31.5 |
| Earthing Switch Peak Stability Current | 50kA | 50kA |
| Earthing Switch 2s Thermal Stability | 20kA | 20kA |
| Auxiliary Circuit Voltage | AC/DC 110V, 220V | AC/DC 110V, 220V |
| Mechanical Life | 10,000 operations | 10,000 operations |
The 12kV Load Break Switch-Fuse Combination Unit is often used for transformer protection. First confirm transformer capacity: if 1250kVA or below with load current within 125A, choose FZRN25 (with fuse short-circuit protection). If load current is within 630A and short-circuit level does not exceed 20kA, choose FZN25. Both configurations support 1250kVA no-load transformer breaking and are suitable for distribution transformer switching.
| Item | Combination Unit | Circuit Breaker + Relay Protection |
| Equipment Composition | Load switch + fuse integrated | Circuit breaker + CT + protection device |
| Cabinet Components | Fewer, simpler wiring | More, complex wiring |
| Short-Circuit Response | Fuse acts directly, fast response | Protection device acts, needs time coordination |
| Overall Cost | Lower | Higher |
| Applications | Small- to medium capacity, transformer protection | Large capacity, complex protection coordination |
| Maintenance | Simple fuse replacement | Periodic protection device calibration |
| Earthing Switch | Integrated, easy operation | Requires separate earthing switch |
In small- to medium capacity distribution and transformer protection, the combination unit provides a simpler structure, faster short-circuit response, and lower overall cost compared with a circuit breaker + relay protection solution.
The 12kV Load Break Switch-Fuse Combination Unit is mainly used in 12kV medium-voltage distribution systems, including:
The product has been exported to Southeast Asia and parts of Europe, and is used in power utilities, power plants, and mining enterprises.
Dongfa Intelligent was founded in 2012 and has focused on high-voltage electrical manufacturing for 14 years. For the two configuration requirements of load switch-fuse combination units, the company provides project customization. FZN25 or FZRN25 can be selected based on transformer capacity, load current, and short-circuit level. Mounting dimensions and auxiliary circuit voltage can be adjusted according to switchgear requirements. Technical engineers are available to respond to selection questions.
Each combination unit undergoes resistance test, mechanical operation test, withstand voltage test, and vacuum degree inspection before shipment. Test records are traceable and available upon request. The company is ISO 9001, ISO 14001, and ISO 45001 certified, with CNAS/IAF recognized testing capability. Products are manufactured according to GB standards and IEC 62271.
The factory is located in Yueqing Economic Development Zone, Wenzhou, Zhejiang, covering over 2,000 m². It has 17 employees, 4 technical engineers, 2 production lines, and 1 set of testing equipment. Monthly capacity is 600-700 units, and annual capacity is 7,000-8,000 units. Products have been exported to Southeast Asia and parts of Europe.
A: Please provide rated current, short-circuit requirements, fuse model, auxiliary voltage, application, and quantity. The 12kV Load Break Switch-Fuse Combination Unit can be quoted based on these parameters.
A: Standard products support MOQ 1 unit. Lead time is 7-15 working days for standard products and 15-30 working days for customized configurations.
A: FZN25-12D/T630-20 is for 630A load with short-circuit level not exceeding 20kA. FZRN25-12D/T125-31.5 is for 125A load with 31.5kA short-circuit breaking and fuse protection.
A: Yes. Mounting dimensions, auxiliary circuit voltage, and configuration can be adjusted according to switchgear requirements.
A: We are a manufacturer with our own factory in Yueqing, Zhejiang, founded in 2012. Factory audits are supported.
A: Each unit undergoes resistance test, mechanical operation test, withstand voltage test, and vacuum degree inspection before shipment.
For technical review and quotation, please provide the following information:
For replacement projects, please also include the original model and switchgear information when available.
Address
No. 281, Wei 18th Road, Yueqing Economic Development Zone, Yueqing, Wenzhou, Zhejiang, China
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