Overview
The FZW28Z-12 (FFK) is a 12kV, 50Hz outdoor pole-mounted vacuum sectionalizing load break switch with both manual and electric operation. Its switch body adopts the imported Toshiba (Japan) VSP5-12 maintenance-free load-switch unit, using vacuum arc extinguishing with SF6 gas insulation. Combining fault detection, protection, control and communication, it is installed on 10kV distribution lines to automatically cancel single-phase-to-ground faults and to isolate phase-to-phase short-circuit faults.
The switch is applied at the T-connection or at the user end of 10kV overhead feeders, and at other qualifying branch connection points. A compact spring operating mechanism and aviation-plug secondary connections allow straightforward combination with an intelligent controller for automated distribution and remote operation.
Model Designation
Model format: FZW 28 Z – 12 / 630 – 20
- FZW: Outdoor vacuum load switch
- 28: Design sequence number
- Z: Spring operating mechanism
- 12: Rated voltage (kV)
- 630: Rated current (A)
- 20: Rated short-circuit breaking current (kA)
Construction
The FZW28Z-12 integrates a vacuum-interrupter load-switch unit (imported Toshiba VSP5-12) inside a sealed, SF6-insulated enclosure, giving maintenance-free operation with no gas leakage and full isolation from the outdoor environment. A miniaturized spring operating mechanism with manual and electric options provides reliable 10,000-operation life, while aviation plugs bring the secondary control, sensing and communication circuits to an external intelligent controller. The unit is designed for quick pole mounting with standard brackets for repeated sectionalizing and fault-isolation duty on automated 10kV distribution networks.
Technical Parameters
Service Conditions
- Ambient Temperature: -40 degC to +40 degC
- Altitude: <=3000 m (higher altitude on request with a correspondingly higher rated insulation level)
- Relative Humidity: Daily average <=90%, monthly average <=90%
- Wind Pressure: <=700 Pa (equivalent to wind speed 34 m/s)
- Neutral Earthing: Solidly earthed, earthed via arc-suppression coil, or earthed via low resistance
- Installation Environment: Outdoor, no explosive or severely corrosive gas, no frequent severe vibration
Technical Data
| No. | Item | Unit | Parameter |
|---|---|---|---|
| 1 | Rated voltage | kV | 12 |
| 2 | Rated frequency | Hz | 50 |
| 3 | Rated current | A | 630 |
| 4 | Rated short-circuit breaking current | kA | 20 |
| 5 | Rated short-time withstand current (4 s) | kA | 12.5 / 16 / 20 |
| 6 | Rated short-circuit making current (peak) | kA | 31.5 / 40 / 50 |
| 7 | 1 min power-frequency withstand voltage (phase-to-phase / phase-to-earth / across open contacts) | kV | Dry 42 / 48; Wet 34 |
| 8 | Lightning impulse withstand voltage (peak, phase-to-phase / phase-to-earth / across open contacts) | kV | 75 / 85 |
| 9 | Mechanical life | times | 10000 |
| 10 | Net weight | kg | 210 |
Installation & Wiring
Installation Diagram
The FZW28Z-12 is designed for standard pole-mounted installation using brackets, with the controller mounted separately on the pole. Adequate clearance must be maintained around the unit for safe operation and maintenance, and all primary and secondary connections must comply with local utility standards. The certified outline and mounting dimension drawing is supplied with each unit.
Outline Dimensions
| Dimension | Value (mm) |
|---|---|
| Overall height | 808 |
| Overall width (across cable outlets) | 795 |
| Switch body width | 400 |
| Switch body height | 658 |
| Control device height | 340 |
| Control device diameter | Φ300 |
Selection & FAQs
Selection Guide
- Confirm a 12kV, 50Hz three-phase pole-mounted sectionalizing application and the 630A rated current after load assessment.
- Select the short-time withstand rating (12.5 / 16 / 20 kA at 4s) above the prospective fault level and verify the corresponding making and breaking ratings.
- Confirm the neutral earthing arrangement (solidly earthed, via arc-suppression coil, or via low resistance) with site wind pressure (<=700Pa) and altitude (<=3000m).
- Specify control voltage, manual/motor operation, CT ratios, aviation-plug secondary circuits and controller protocol for local/remote automation.
- Check outdoor service from -40 degC to +40 degC, pole strength, mounting clearances, surge protection and grounding.
Frequently Asked Questions
Q1: What is the FZW28Z-12 used for?
It is a 12kV outdoor pole-mounted vacuum sectionalizing load break switch (FFK) for 10kV distribution lines, applied at user T-connections or line ends to automatically detect, cancel and isolate ground and phase-to-phase faults.
Q2: What are the rated current and short-circuit ratings?
Rated current is 630A at 50Hz. The rated short-circuit breaking current is 20kA, short-time withstand is 12.5 / 16 / 20kA for 4s, and the peak making current is 31.5 / 40 / 50kA.
Q3: How does a load break switch differ from a circuit breaker?
A load break switch makes and breaks load current and, in sectionalizing duty, controlled fault currents; it is normally coordinated with an upstream breaker or recloser that clears high fault currents. Confirm the coordination with our engineering team.
Q4: What insulation level does it provide?
The 1-minute power-frequency withstand voltage is 42/48kV dry and 34kV wet, and the lightning impulse withstand voltage is 75/85kV (phase-to-phase / phase-to-earth / across open contacts).
Q5: Which neutral earthing systems are supported?
Solidly earthed, earthed via an arc-suppression coil, or earthed via low resistance. Select the matching CT and controller settings for your system.
Q6: What are the service conditions?
Ambient temperature from -40 degC to +40 degC, altitude up to 3000m (higher on request), wind pressure up to 700Pa (34m/s), and daily/monthly relative humidity up to 90%.