Product Overview
The DNF7 series is a medium-voltage air-insulated switchgear manufactured by Schneider Electric, implementing the company’s unified technology, production, and quality standards. It is widely applied in various power generation and distribution systems and can ensure safe and reliable operation under all kinds of service conditions.
Product Positioning and Core Value
The DNF7 switchgear is positioned as a digital medium-voltage power distribution product, emphasizing reliability, safety, simplicity, efficiency, and smart connectivity. It embodies Schneider Electric’s engineering heritage and integrates EcoStruxure-ready smart solutions for the digital transformation of power assets.
Technical Specifications
| Parameter | Value | Notes |
|---|---|---|
| Rated Voltage | 40.5 kV | — |
| Rated Frequency | 50/60 Hz | — |
| Rated Power-frequency Withstand Voltage (1 min) | 95 kV | — |
| Rated Lightning Impulse Withstand Voltage (peak) | 185 kV | — |
| Rated Current (Ir) | 630 / 1250 / 1600 / 2000 / 2500 / 3150 A | With fan for forced cooling |
| Rated Short-circuit Breaking Current (Isc) | 25 / 31.5 kA | — |
| Rated Short-time Withstand Current | 25 / 31.5 kA | — |
| Maximum Arcing Fault Current | 31.5 kA | — |
| Arc Fault Duration Time | 1 s | — |
| Anti-internal Arc Rating | AFLR 31.5 kA/1s | IAC classification |
| Designed Service Life | Up to 30 years | Under specified conditions |
| Cubicle Type | LSC2B | IEC 62271-200 / GB/T 3906 |
| Compartment Classification | PM level | Metal partitions segregate compartments |
| Standard Cabinet Height | 2400 mm | Excludes pressure relief device |
| Cabinet Width | 1200 mm | Standard |
| Cabinet Depth | 2750 mm (std) / 3400 mm (deepened) | — |
Product Architecture
The DNF7 cubicle is of LSC2B type as defined by IEC 62271-200 and GB/T 3906. The medium voltage parts are compartmented using metal partitions (PM class) which are connected to earth and separate:
- The Busbars
- The withdrawable part (circuit breaker, fuse-contactor, disconnector truck or earthing truck)
- Cable compartment (cable connections, earthing switches, current sensors and voltage transformers)
The low voltage auxiliaries and metering compartments are independently separated from the medium voltage compartments, greatly protecting personnel safety. When a compartment of the main circuit is opened, other compartments and functional units have the feasibility of remaining in a live state.
Functional Solutions
DNF7 series switchgear offers comprehensive functional solutions to meet diverse application needs:
- Incoming / Feeder
- Bus tie / Disconnector
- Bus riser
- Potential Transformer
- Metering
Key Features
1 Safety and Reliability
The DNF7 switchgear is engineered with multiple layers of safety and reliability features:
- Anti-internal arc rating up to AFLR 31.5 kA/1s
- Reliable interlocking devices fully meeting the requirements of “five-prevention”
- Ergonomic operation interface with clear operation instructions to avoid misoperations
- Designed service life reaching 30 years under specified installation and operation environment conditions
- Full-metal enclosure design enhancing protection against accidental contact
- LSC2B classification: metal partitions segregate various compartments, allowing safe intervention on one compartment even if others remain energized
- PM level compartment classification
- Operations performed with door closed
- Quick-closing earthing switch with short-circuit closing capability
- Complete mechanical and electrical interlocking system guiding operators to perform correct operations
- Modular design making installation and maintenance more convenient
- Floor-mounted handcart equipped with anti-tipping mechanism to protect personal safety
2 High-Quality Design
Schneider self-designed key components are adopted for DNF7 switchgear, including:
- Vacuum circuit breaker (vacuum interrupter, operating mechanism, solid-sealed pole)
- Main circuit bus
- Earthing switch
- Relay protection device
Conduct simulation calculations for insulation performance, temperature rise performance, and internal arc resistance performance to optimize key component design. Design/Process Failure Mode and Effects Analysis (DFMEA/PFMEA) ensures reliability of component design and consistency of production processes.
DNF7 range performances have been proven successfully by comprehensive type tests performed in independent and accredited laboratories in accordance with IEC and GB standards. Each DNF7 switchgear undergoes rigorous and systematic factory-acceptance tests.
3 Design Innovation
Double-shielded Contact Box
The double-shielded contact box contains two layers of shielding nets — high-voltage shielding and grounding shielding (inner and outer shielding nets). The inner shielding net is connected to the conductor of the primary main circuit. If the outer shielding net is earthed through the enclosure, it will be at zero potential. Advantages include:
- Uniform current density distribution and high current-carrying capacity
- Excellent electric field distribution enabling the core insulation to have a long service life
- Branch busbars and static contacts adopt integrated design with heat dissipated from both internal and external surfaces
- Optimizes electric field distribution in the air gap inside the contact box, reducing partial discharge risk
- Invention patent — integrating live display sensor function via capacitive voltage division principle
Tubular Busbar
Tubular main busbars and branch busbars feature sufficient insulation margin and excellent electric field distribution. The new-type main circuit design offers good heat dissipation performance, enhancing long-term operation safety.
Anti-arc Propulsion Window
The new-generation DNF7 adopts an embedded propulsion window operation interface with Schneider industrial design style — concise, beautiful, and easy to operate. After the propulsion window is opened, operations such as handcart insertion/withdrawal, emergency tripping, and unlocking of the earthing switch can be carried out. After closing, it reliably prevents arc leakage.
4 Simplicity and Efficiency
Easy Operation
- Operation and maintenance in front of the cabinet can be realized
- Intuitive single-line diagrams and graphical displays on the front of each functional unit enable clear comprehension of component status
- Embedded sliding window design — clear and easy to understand; reliably prevents arc leakage when closed
- Floor-mounted handcart equipped with anti-tipping mechanism
Efficient Maintenance
- Circuit breaker handcarts of the same specifications can be interchanged without any adjustment
- Each switchgear and front panel equipped with QR code — scanning provides access to technical information, drawings, single-line diagrams
- Integrated intelligent solution facilitates efficient operation and maintenance
Easy to Install
- Cable compartment has sufficient space for cable connections
- Voltage transformer, surge arrester and other components can be installed in the cable compartment as needed
- Cable entry and exit can be from top or bottom
5 Personnel Protection — Internal Arc Classification (IAC)
The DNF7 series switchgear meets the IAC internal arc classification in accordance with IEC 62271-200 and GB/T 3906 standards:
- Accessibility: A (Restricted to authorized personnel only)
- For front side (F), lateral side (L), rear side (R)
- Maximum Arc fault current: 31.5 kA
- Arc fault duration: 1s
All five IAC criteria are met:
- Correctly secured doors and covers do not open
- No fragmentation of the enclosure during arc fault duration
- Arcing does not cause holes by burning through classified sides up to 2000 mm
- Indicators do not ignite due to hot gases or burning liquids
- The enclosure remains connected to the earthing point
6 Smart Solutions (EcoStruxure-ready)
Smart DNF7 switchgear connects to the EcoStruxure architecture at the pre-control level, ensuring more reliable continuous power supply. Key smart features include:
- Online temperature monitoring: Schneider Electric TH110 series temperature sensors for main busbar joints and cable joints; embedded sensors in circuit-breaker contact arms (measurement range: -25℃ to +130℃, accuracy: +/-1℃)
- On-line monitoring of circuit breaker characteristics: data acquisition of closing coils, opening coils, and energy-storage motors for real-time monitoring of mechanism performance
- On-line video monitoring: remote/local viewing of circuit breaker handcart position and earthing switch status (1920×1080 resolution, 100,000 hours service life)
- Arc flash protection: VAMP arc flash protection system detecting arc light and measuring fault current; operation time far faster than conventional protection devices (2-7ms response)
- Online monitoring of remaining electrical life: based on vacuum circuit breaker interrupting capacity parameter curves, calculating remaining interrupting times
- PMBox Proactive Operation and Maintenance Expert: integrated information from interconnected devices for predictive maintenance and asset management
Smart DNF7 integrates with:
- EcoStruxure™ Energy Hub — one-stop integrated operation platform
- PMB/PMB Easy — integrated operation and maintenance management unit
- PO — Monitoring platform for modular deployment of medium- and low-voltage cabinets
- Schneider EcoStruxure™ Asset Advisor — cloud platform for professional data analysis and proactive maintenance recommendations
7 Key Components
HVX Series Vacuum Circuit Breaker
HVX series vacuum circuit breakers embody Schneider Electric’s century-old wisdom in the medium-voltage field. As medium-voltage vacuum circuit breakers developed based on global R&D and design experience, they are widely applied in power grids, petrochemical industry, public infrastructure, industrial enterprises, and transportation.
Key features:
- High-performance vacuum interrupter chamber and solid-sealed polar column
- Advanced Vacuum Arc Extinction Technology: copper-chromium alloy contacts with one-time sealing & exhaust process combined with high-voltage, high-current dual conditioning
- APG automatic pressure gel molding process — resistant to impact and corrosion
- Modular operating mechanism — greatly reduces complexity, improves reliability, brings more stable action performance and longer mechanical service life
- Intelligent functions: digital temperature monitoring and circuit breaker characteristic monitoring through intelligent sensing and interaction
Typical applications:
- Making and breaking of rated short-circuit current
- Breaking of asymmetric current
- Automatic reclosing
- Making of no-load cables and no-load overhead lines
- Making of single or back-to-back capacitor banks
- Out-of-step breaking
- Making of no-load transformers
- Breaking of fault current in phase-to-ground faults
- Making of motors and no-load inductors
PowerLogic Series Integrated Relay Protection Device
PowerLogic series protection devices are developed based on Schneider Electric’s over 100 years of experience in manufacturing relay protection products:
- PowerLogic P3: Universal model covering feeder, motor and transformer applications; supports 9 communication protocols; virtual “analog tester” for accelerated debugging; advanced model with embedded arc-proof function
- PowerLogic P5: Omni-directional condition monitoring with proactive risk early warning; modular hardware design with unified spare parts; Achilles network security certification
- VAMP arc protection system: arc + current protection principle; fault location and isolation within 2-7ms; modular design (main unit, I/O unit, arc probe); 24/7 online self-monitoring
- PowerLogic A1/A3 arc protection device: arc + current protection; 2-7ms fault isolation; modular design; 24/7 self-test monitoring
Withdrawable Components
DNF7 switchgear components feature long service life, maintenance-free live parts, high electrical life, safe operation, and environmental friendliness:
- Circuit breakers (HVX series) — connect/disconnect load current; automatically disconnect fault current during malfunctions
- Disconnector truck (UTX series) — isolate high-voltage power supply, form clearly visible break for safe maintenance
- Voltage transformer truck — measure bus voltage; handcart design enables easy movement, installation, test and replacement
- Grounding/earthing truck — ensure safety of maintenance personnel during failure maintenance; bus grounding with reliable interlocking devices
- Propelling mechanisms for racking in and out
- Relevant interlocking devices
Application Scenarios
The DNF7 series medium-voltage switchgear is widely applicable across diverse industries and sectors:
1 Power Grid and Energy
- Power plant and electric power company
- Power grid and power distribution system
- Water affairs and environmental protection public utilities
2 Commercial Buildings
- Hotel
- Large office building
3 Infrastructure
Various infrastructure projects requiring reliable medium-voltage power distribution.
4 Heavy Industry
- Mining industry and metallurgy
- Chemical engineering and oil & gas
- Building materials and cement
5 Manufacturing Industry
- Automobile
- Intelligent manufacturing
6 New Energy
- Photovoltaics (solar power)
- Wind power
Operating Conditions
1 Ambient Conditions
- Ambient temperature: -25℃ to +40℃
- Average temperature over 24 hours: Not exceeding 35℃
- Altitude: Not exceeding 1000 meters
- Surrounding air: No significant contamination by dust, smoke, corrosive or flammable gases, vapors, or salt fog
- Daily average relative humidity: <= 95%; Monthly average: <= 90%
- Daily average water vapor pressure: <= 2.2 kPa; Monthly average: <= 1.8 kPa
2 Special Conditions
For high temperature (derating may be required), corrosive environments, or vibration (adaptation may be required), please contact Schneider Electric.
