Product Overview
The ZW20A-12 is an outdoor pole-mounted vacuum circuit breaker for 12 kV 50 Hz three-phase AC distribution systems, providing switching and protection against load, overload and short-circuit currents in substations, industrial plants and rural networks. Rated currents of 630 A and 1250 A combine with breaking capacities of 16, 20 and 25 kA, and the vacuum-plus-SF6 insulated design supports remote monitoring and distribution automation.
Product Display
Model Designation
Model format: ZW 20 − 12 / T □ − □
- ZW — Vacuum circuit breaker
- 20 — Product series design number
- 12 — Rated voltage (kV)
- T — Spring-operated mechanism
- First □ — Rated current (A)
- Second □ — Rated short-circuit breaking current (kA)
Service Conditions
- Ambient temperature: −40 °C to +40 °C
- Altitude: not exceeding 1000 m above sea level
- Relative humidity: daily average ≤ 95%, monthly average ≤ 90%
- Seismic intensity: not exceeding degree 8
- Installation site free from fire, explosion risk, severe pollution and chemical corrosion
Construction
The ZW20A-12 pairs vacuum arc extinction with SF6 gas insulation on the proven ZW20-12 platform, giving high dielectric strength and hermetic sealing. A compact spring-operated mechanism with direct chain drive and multi-stage tripping keeps mechanical reliability high, while the bracelet contact structure of the main current path limits contact resistance and thermal rise.
The sealed enclosure holds stable operation through high humidity, dust and wide temperature swings with zero SF6 leakage and explosion-proof performance. Built-in current transformers interface with protection relays, primary terminals are marked P1/P2 with instrument-transformer secondary terminals S1/S2, and both manual and motorised operation are supported.
Technical Data
| Item | Unit | Value |
|---|---|---|
| Rated Voltage | kV | 12 |
| Rated Frequency | Hz | 50 |
| Rated Current | A | 630 1250 |
| Rated Short-Circuit Breaking Current | kA | 16 20 25 |
| Rated Short-Circuit Making Current (peak) | kA | 40 50 63 |
| Rated Short-Time Withstand Current (3 s) | kA | 16 20 25 |
| Power Frequency Withstand Voltage (1 min) | kV | 42 |
| Lightning Impulse Withstand Voltage | kV | 75 |
| Mechanical Life | Operations | 10000 |
| SF6 Gas Pressure (gauge, 20 °C) | MPa | 0.01 |
Standards
Manufactured and tested in accordance with IEC and GB standards for high-voltage AC circuit breakers, including IEC 62271-100 and GB 1984.
Installation & Dimensions
Installation Diagram
The breaker mounts on standard utility poles with clear phase spacing and secure anchoring points to remain mechanically stable under wind and ice loading.
| Dimension | Value (mm) |
|---|---|
| Overall Height | 1850 |
| Overall Width (phase-to-phase) | 630 |
| Mounting Bracket Height | 1200 |
| Primary Terminal Spacing (P1–P2) | 350 |
| Secondary Terminal Block Size | 120 x 80 |