Overview
The FZW28-12 outdoor high-voltage vacuum load break switch is engineered for 12kV, 50Hz three-phase AC power distribution systems. It reliably handles normal load currents, overload conditions, and short-circuit faults, making it ideal for substations, industrial plants, rural grid protection, and automated distribution networks requiring frequent switching.
Built with a vacuum interrupter integrated into a sealed control unit via aviation connectors and control cables, the FZW28-12 accurately detects and isolates both interphase and zero-sequence fault currentsâwhether local or downstreamâensuring robust performance across diverse outdoor environments and neutral grounding configurations.
Key Ratings Snapshot
| Parameter | Value |
|---|---|
| Rated Voltage | 12 kV |
| Rated Frequency | 50 Hz |
| Rated Current | 630 A |
| Rated Short-Circuit Breaking Current | 20 kA |
| Rated Short-Time Withstand Current (3s) | 20 kA |
| Rated Peak Withstand Current | 50 kA |
| Power Frequency Withstand Voltage (1 min) | 42 kV (phase-earth) 48 kV (open contacts) |
| Lightning Impulse Withstand Voltage | 75 kV (phase-earth) 85 kV (open contacts) |
| Mechanical Life | >=10,000 operations |
| Electrical Life (at rated current) | >=10,000 operations |
Model Designation
- FZW: Outdoor vacuum load break switch.
- 28: Design sequence number for the product series.
- 12: Rated voltage (kV).
- /T: Denotes the spring-operated mechanism.
- â¡: Represents the rated current (A).
- â¡: Indicates the rated short-time withstand current (kA).
Construction
The FZW28-12 features automatic locking upon phase-to-phase short-circuit faults: after a substation breaker or recloser trips due to a downstream fault, the switch trips and locks out, enabling rapid isolation of the faulty branch and fast reclosing of the main feeder to restore power to healthy sections. It also supports quick fault location through user outage reports and handheld diagnostic tools, minimizing service interruption time.
For single-phase ground faults on user branch lines, the switch instantly isolates the affected segment while maintaining continuity for the rest of the network. Its rugged, sealed design ensures reliable operation under various neutral grounding schemesâincluding solidly grounded, resistance grounded, and ungrounded systemsâdelivering high safety and resilience in outdoor distribution applications.
Technical Parameters
Service Conditions
- Ambient Temperature: -40 degC to +45 degC
- Altitude: <=1000 m
- Relative Humidity: <=95% (daily average), <=90% (monthly average)
- Pollution Degree: Class III
- Installation Environment: Outdoor, no explosive or corrosive gases, no severe vibration or shock
Technical Data
| Parameter | Value |
|---|---|
| Rated Voltage | 12 kV |
| Rated Frequency | 50 Hz |
| Rated Current | 630 A |
| Rated Short-Circuit Breaking Current | 20 kA |
| Rated Short-Time Withstand Current (3s) | 20 kA |
| Rated Peak Withstand Current | 50 kA |
| Power Frequency Withstand Voltage (1 min) | 42 kV (between phases and earth) 48 kV (across open contacts) |
| Lightning Impulse Withstand Voltage (peak) | 75 kV (between phases and earth) 85 kV (across open contacts) |
| Mechanical Life | >=10,000 operations |
| Electrical Life (at rated current) | >=10,000 operations |
Installation & Wiring
Installation Diagram
The FZW28-12 is designed for pole-mounted installation using standard brackets. Adequate clearance must be maintained around the unit to ensure safe operation and ease of maintenance. All electrical connections must comply with local utility standards and national electrical codes.
Outline Dimensions
| Dimension | Value (mm) |
|---|---|
| Total Height | 1320 |
| Width (phase spacing) | 300 |
| Depth | 580 |
| Mounting Hole Spacing (vertical) | 400 |
| Mounting Hole Spacing (horizontal) | 220 |
| Weight | â85 kg |
Selection & FAQs
Selection Guide
- Confirm the required device function: load switching and automatic sectionalizing are not automatically equivalent to circuit-breaker fault interruption.
- Verify the 12kV, 50Hz and 630A ratings, then obtain type-test evidence for any claimed 20kA breaking, three-second withstand and 50kA peak duties.
- Define the upstream breaker/recloser sequence, phase and zero-sequence pickup settings, trip-lockout logic and reclosing dead time for selective branch isolation.
- Confirm compatibility with solidly grounded, resistance-grounded or ungrounded neutral systems and specify the correct CT inputs, controller and communication interface.
- Check −40°C to +45°C Class III outdoor conditions, pole strength, 85kg equipment load, mounting clearances, surge protection and grounding.
Frequently Asked Questions
Q1: Can this switch interrupt 20kA short-circuit faults?
Yes, it features a rated short-circuit breaking current of 20 kA. The short-time withstand current is also 20 kA for 3 seconds. Verify prospective fault levels with our engineering team.
Q2: Which environmental conditions are required for outdoor installation?
It requires outdoor installation free from explosive gases, severe vibration, or shock. Ambient temperature must remain between -40°C and +45°C at altitudes up to 1000m. Contact us for high-altitude derating details.
Q3: How does the insulation withstand voltage perform?
The power frequency withstand voltage is 42 kV to earth and 48 kV across open contacts. Lightning impulse withstand peaks at 75 kV and 85 kV respectively. Confirm specific clearance requirements for your substation.
Q4: What routine factory tests are performed before shipment?
Standard routine tests include power frequency withstand, mechanical operation, and contact resistance measurements. Full type test reports are available upon request. Specify required third-party certifications during the inquiry stage.
Q5: Are custom control options available for this model?
Yes, we offer customizable control and protection relay integrations subject to project confirmation. Standard mechanical and electrical life exceeds 10,000 operations. Contact our sales team for lead times and customization fees.
Q6: Where is the FZW28-12 load break switch applied?
It is primarily used in 12kV outdoor distribution networks for load switching and fault isolation. Rated for 630A continuous current at 50Hz. Request the application manual for specific grid integration guidelines.
Q7: When is the FZW28-12 switch suitable for outdoor grids?
It is suitable for 12kV outdoor distribution networks requiring Class III pollution degree resistance. Rated for 630A continuous current at 50Hz. Contact us to request the full compliance declaration and application manual.