The FZW-40.5 outdoor high-voltage vacuum load break switch is a three-pole switching device developed for 40.5 kV, 50 Hz overhead distribution networks. It makes and breaks load current under normal operation, and it can also break the capacitive charging current of overhead lines, cable lines and capacitor banks within a defined distance. Each pole combines a vacuum interrupter with a visible isolating gap, so load breaking and disconnecting are performed by one compact unit.
The switch provides sectioning, isolating, connecting and changeover functions for urban and rural networks, railways and petrochemical plants with overhead distribution lines. Type tests and long-term trial operation confirm a high breaking capacity, long electrical endurance, suitability for frequent operation and low maintenance. Performance conforms to GB 3804 and IEC standards.
Model Designation
The type designation FZW□-40.5/1250-25 reads as follows:
- FZW: outdoor vacuum load break switch
- □: design sequence number
- 40.5: rated voltage, kV
- T: spring operating mechanism
- 1250: rated current, A
- 25: rated short-time withstand current, kA
Other current and withstand-current combinations are available on request.
Construction and Design
Three poles are carried on a galvanized steel frame with red composite insulator columns. Each pole pairs a vacuum interrupter with a serial isolating gap, providing visible isolation in the open position. A side-mounted CJ□-10XJG cabinet houses the spring operating mechanism; the frame base suits structure-mounted and pole-mounted installation.
Operating Function and Application
Under load the arc is extinguished in the vacuum interrupters; the isolating blades then open to give a visible safety gap. Typical duties are feeder sectioning and connecting, isolation for maintenance, and supply-route changeover in urban and rural networks, railways and petrochemical plants.
Technical Parameters
Service Conditions
- Altitude: Not more than 2000m
- Ambient temperature: -30℃ ~ +40℃
- Wind speed: Not more than 35m/s
- Relative humidity: Daily average not more than 95%, monthly average not more than 90%
- Vibration: No frequent severe vibration
Technical Data
| No. | Item | Unit | Parameter |
|---|---|---|---|
| 1 | Rated voltage | kV | 40.5 |
| 2 | Rated frequency | Hz | 50 |
| 3 | Rated current | A | 1250 |
| 4 | Rated active load breaking current | A | 1250 |
| 5 | Rated closed-loop breaking current | A | 1250 |
| 6 | 5% rated active load breaking current | A | 62.5 |
| 7 | Rated cable charging breaking current | A | 25 |
| 8 | 1 min power-frequency withstand voltage: vacuum gap / phase-to-phase & phase-to-earth / isolation gap | kV | 68/95/110 |
| 9 | Lightning impulse withstand voltage: phase-to-phase & phase-to-earth / isolation gap | kV | 185/215 |
| 10 | Rated short-time withstand current (thermal stability) | kA | 25 |
| 11 | Rated short-circuit duration | s | 4 |
| 12 | Rated peak withstand current (dynamic stability) | kA | 63 |
| 13 | Rated short-circuit making current | kA | 63 |
| 14 | Mechanical life | operations | 10000 |
| 15 | Permissible contact wear of vacuum interrupter | mm | 0.6 |
| 16 | Manual operating torque | Nm | ≤300 |
Standards
- The product conforms to GB 3804 and IEC standards for high-voltage load break switches
- Type tested and verified by long-term trial operation
Installation & Wiring
Installation and Commissioning
- Mounting: frame levelled on a steel structure or pole platform, base fully bolted; earthing terminal connected to the earth grid with a dedicated conductor.
- Mechanism checks: three-pole simultaneity, contact travel of vacuum interrupters and isolating blades, smooth charge and release of the spring mechanism, manual operating torque ≤300 Nm.
- Before energization: power-frequency withstand check on the main circuit; terminal markings verified against the approved outline drawing.
Applications
- Sectioning and connecting 40.5 kV overhead feeders
- Isolating transformers, capacitor banks and line sections for maintenance with a visible gap
- Changeover between supply routes in loop and radial overhead systems
- Railway power supply and petrochemical plant overhead lines
Selection & FAQs
Selection Guide
- State the rated voltage. The standard type is 40.5 kV at 50 Hz for overhead networks.
- State the rated current. The standard unit is 1250 A; the active load and closed-loop breaking currents equal the rated current.
- Confirm the breaking duty. Cable or capacitor-bank charging current up to 25 A; 5% rated active load breaking current 62.5 A.
- Check the short-time duty. 25 kA for 4 s thermal, 63 kA peak and making current.
- Confirm the service environment. Altitude ≤2000 m, ambient -30℃~+40℃, wind ≤35 m/s; higher altitudes require derating agreement.
FAQs
Q1: What is the FZW-40.5 load break switch used for?
It is used on 40.5 kV overhead distribution networks to make and break load current, to break cable and capacitor-bank charging currents, and to provide sectioning, isolating, connecting and changeover functions with a visible isolation gap in the open position.
Q2: How does the FZW-40.5 differ from indoor load break switches such as the FN3-12 and FN5-12?
The FN3-12 and FN5-12 are indoor 12 kV load break switches for switchgear cells and indoor substations, while the FZW-40.5 is an outdoor 40.5 kV unit for overhead lines with composite insulator poles, a weatherproof spring operating cabinet and an integrated visible isolating gap per pole.
Q3: How do I read the model designation FZW□-40.5/1250-25?
FZW = outdoor vacuum load break switch, □ = design sequence number, 40.5 = rated voltage in kV, T = spring operating mechanism, 1250 = rated current in A, 25 = rated short-time withstand current in kA.
Q4: What currents can the FZW-40.5 make and break?
It breaks and makes the rated active load and closed-loop current of 1250 A, 5% rated active load current of 62.5 A, and cable or capacitor-bank charging currents up to 25 A. It is not intended for breaking fault currents; short-circuit protection must be provided by upstream devices.
Q5: What are the insulation and short-time withstand ratings?
The 1 min power-frequency withstand voltage is 68 kV across the vacuum gap, 95 kV phase-to-phase and phase-to-earth, and 110 kV across the isolation gap; the lightning impulse withstand is 185/215 kV. The short-time withstand current is 25 kA for 4 s with 63 kA peak and making current.
Q6: Can special parameters or service conditions be customized?
Yes. If the user’s data go beyond the ranges listed in the technical data table, or the site exceeds 2000 m altitude or the standard humidity and wind conditions, the design can be adapted by agreement between manufacturer and purchaser; final parameters are subject to approved specifications.