ZW8-12(G) Outdoor Vacuum Circuit Breaker 630A 6.3-20kA 12kV | Metal-Enclosed SMC Insulated Feeder Protection IEC GB Thomas Electric

Product Overview

The ZW8-12(G) is a 12 kV 50 Hz three-phase outdoor vacuum circuit breaker for rural distribution networks, urban grids and small power systems, controlling and protecting feeders against load, overload and short-circuit currents. A 630 A rated current combines with breaking capacities of 6.3, 12.5 and 20 kA, and the metal-enclosed, SMC-insulated design withstands severe pollution sites; the G variant integrates an isolating switch for visible sectionalising.

Product Display

ZW8-12(G) Outdoor High-Voltage Vacuum Circuit Breaker - display

ZW8-12(G) Outdoor High-Voltage Vacuum Circuit Breaker - poster_display

Model Designation

ZW8-12(G) Outdoor High-Voltage Vacuum Circuit Breaker - model

Model format: ZW 8 − 12 G / 630 − □

Z — Vacuum circuit breaker
W — Outdoor type
8 — Design sequence number
12 — Rated voltage (kV)
G — With integrated isolating switch
/630 — Rated current (A)
□ — Rated short-circuit breaking current (kA)

Service Conditions

Ambient temperature: −40 °C to +40 °C
Altitude: not exceeding 3000 m (insulation adjustments required above this)
Pollution: suitable for Grade V environments including dust, smoke and salt mist
Wind speed: not exceeding 34 m/s (equivalent to 700 Pa pressure)
Negligible external vibration or seismic impact assumed; custom environments available on request

Construction

The ZW8-12(G) uses a three-phase pillar-type dry design with fully sealed construction and SMC insulating materials, giving high phase-to-phase and phase-to-ground insulation strength and reliable service in hot, humid climates. The metal-enclosed body houses the three-phase vacuum interrupters, and the G variant adds an integrated isolating switch so the unit can serve as a sectionaliser.

A CT23 spring-operated mechanism provides manual and electric operation, with primary terminals marked P1/P2 and secondary terminals S1/S2 for the built-in current transformers. A built-in potential transformer with per-phase fuses and a zero-sequence current transformer support metering and earth-fault protection.

Technical Data

Item	Unit	6.3 kA	12.5 kA	20 kA
Rated Voltage	kV	12	12	12
Rated Current	A	630	630	630
Rated Short-Circuit Breaking Current	kA	6.3	12.5	20
Rated Short-Circuit Making Current (peak)	kA	16	31.5	50
Rated Peak Withstand Current	kA	16	31.5	50
Rated Short-Time Withstand Current	kA	6.3	12.5	20
Lightning Impulse Withstand Voltage (peak)	kV	75	75	75
Power Frequency Withstand Voltage (1 min)	kV	42	42	42
Rated Operating Sequence	—	O-0.3s-C/O-180s-C/O	O-0.3s-C/O-180s-C/O	O-0.3s-C/O-180s-C/O
Mechanical Life	Operations	10000	10000	10000
Breaking Times at Rated Breaking Current	Times	30	30	30
Closing / Opening Voltage of Mechanism	V	110, 220	110, 220	110, 220
Contact Distance	mm	11 ± 1	11 ± 1	11 ± 1
Overtravel (contact spring compression)	mm	3 ± 0.3	3 ± 0.3	3 ± 0.3
Phase Discrepancy of Closing and Opening	ms	≤ 2	≤ 2	≤ 2
Contact Closing Bounce Time	ms	≤ 2	≤ 2	≤ 2
Average Closing Speed	m/s	1.0 ± 0.2	1.0 ± 0.2	1.0 ± 0.2
Average Opening Speed	m/s	0.7 ± 0.15	0.7 ± 0.15	0.7 ± 0.15
Opening Time at Max Operating Voltage	ms	15-50	15-50	15-50
Opening Time at Min Operating Voltage	ms	30-60	30-60	30-60
Closing Time	ms	25-50	25-50	25-50
Main Circuit Resistance per Phase	μΩ	≤ 120 (with G ≤ 200)	≤ 120 (with G ≤ 200)	≤ 120 (with G ≤ 200)
Permitted Cumulative Contact Wear	mm	3	3	3
Weight	kg	152 (with G 180)	152 (with G 180)	152 (with G 180)
Phase Centre Distance	mm	175 ± 1.5	175 ± 1.5	175 ± 1.5

Selection note: choose the 6.3 kA, 12.5 kA or 20 kA breaking rating above the prospective fault level at the installation point, and verify the matching making and short-time withstand values against feeder load and protection studies.

Standards

Manufactured and tested in accordance with IEC and GB standards for high-voltage AC circuit breakers, including IEC 62271-100 and GB 1984.

Technical note: routine-test reports are issued with each shipment; type-test reports and third-party certification documents are available on request.

Installation & Dimensions

Installation Diagram

ZW8-12(G) Outdoor High-Voltage Vacuum Circuit Breaker - installation

The breaker is mounted on a stable support structure with adequate clearance for operation and maintenance, and contact-blade alignment is verified during installation to avoid mechanical stress. Main components: contact blade, contact base, contact blade support, insulated pull rod, operating handle, isolating-switch support and circuit breaker.

Dimension	Value (mm)
Phase Centre Distance	175 ± 1.5
Contact Distance	11 ± 1
Overtravel	3 ± 0.3

Safety notice: always de-energize and verify isolation before maintenance, and never operate the isolating switch under load.

FAQs

Yes. The sealed, SMC-insulated construction suits Grade V pollution sites including dust, smoke and salt mist, with ambient temperature from -40 °C to +40 °C. Send your site data for a specific pollution-duty assessment.

The 20 kA version is intended for heavy industrial networks and supports a 50 kA peak making current. Confirm the maximum prospective fault level of your grid with our engineering team before selecting the rating.

Standard units are rated up to 3000 m altitude; above this limit insulation adjustments are required. Submit your exact site altitude so the factory can verify or adapt the insulation level.

Yes. Tailored solutions are available for conditions beyond the standard -40 to +40 °C range, 34 m/s wind speed and Grade V pollution duty. Provide your project parameters to our technical department for evaluation.

All versions carry a 630 A rated current at 12 kV with breaking capacities of 6.3 kA, 12.5 kA or 20 kA. Verify the continuous load and fault-level requirements during the specification or bidding phase.

It is used in 12 kV outdoor distribution networks of industrial enterprises, substations and rural grids, including severe pollution areas, where it provides feeder control and protection. The G variant adds visible isolation for sectionalising duty.

The 12.5 kA version has a rated peak withstand current of 31.5 kA, matching its rated short-time withstand duty. Request the full technical datasheet for the complete specification set.

ZW8-12(G) Outdoor High-Voltage Vacuum Circuit Breaker