VTZ-12 1250A vacuum circuit breaker, a special model developed by Tongzhong Electrical Co., Ltd., is an indoor vacuum circuit breaker designed for a rated voltage of 12kV, rated current of 1250A, and AC frequency of 50/60Hz. It adopts a modular operating mechanism with a practical and reliable structural design, providing stable closing and opening performance and convenient operation and maintenance.

The circuit breaker is suitable for a wide range of industrial and mining enterprises, power distribution systems, and power grid equipment, meeting the requirements of various medium-voltage switching and protection applications. It can be configured as a withdrawable handcart unit for use with KYN28A-12 switchgear, enabling flexible installation, withdrawal, and maintenance. It can also be configured as a fixed unit with the corresponding mechanical interlocking components, making it suitable for XGN2 and other fixed-type switchgear cabinets.

With flexible installation options, reliable operating performance, and a modular design, the VTZ-12 1250A provides a practical and dependable solution for medium-voltage power distribution and electrical equipment applications.

Product Specifications

Specification Sheet

No.	Name	Unit	Data
1	Rated Voltage	kV	12
2	Rated Frequency	Hz	50/60
3	Rated Current	A	1250
4	Rated PowerFrequency Withstand Voltage	kV	48(Across the Contact Gaps) / 42(To Ground)
5	Rated Lightning Impulse Withstand Voltage	kV	75
6	Rated Short-Circuit Breaking Current	kA	25/31.5/40/50
7	Rated Short-Circuit Making Current (Peak)	kA	63/80/100/125
8	Rated Withstand Current (Peak)	kA	63/80/100/125
9	Rated Duration of Short-Circuit	s	4
10	Operating Cycles at Rated Short-Circuit Breaking Current	Cycles	E2
11	Mechanical Endurance	Times	30000
12	Standard Operating Sequence	-	O-0.3s-CO-180s-CO
13	Allowable Wear Thickness of Contact	mm	≤3

Mechanical Characteristics

No.	Name	Unit	Data
1	Clearance between Moved and Fixed Contact	mm	9±1
2	Contact Overtravel	mm	3.5±0.5
3	Average Closing Speed	m/s	0.7±0.2
4	Average Opening Speed (Average Speed of First Opening at 6mm)	m/s	1.1±0.2
5	Rated Contact Pressure	N	2500±200N(25kA) 3100±200N(31.5kA) 4800±300N(40kA) 6000±500N(50kA)
6	Closing Time	ms	30～70
7	Opening Time	ms	20～50
8	Contact Bouncing Duration at Closing Operation	ms	≤2
9	No-Simultaneity of Closing/Opening Operations of 3-Phase	ms	≤2

Product Advantages

VTZ-12 1250A vacuum circuit breaker has many advantages:

Performance of circuit breaker：

E2-C2-M2

Convenient maintenance:

the modular mechanism design allows for easy replacement of the closing and opening coils without the need for dismantling other components. This eliminates the need for testing or adjustment after replacement, ensuring users to replace them independently, making subsequent maintenance more convenient.

High conductivity performance:

The product features a well-designed conductive circuit that meets the temperature rise requirements at 1.1 times the rated current, ensuring reliable current-carrying performance. This design also helps maintain stable operation and improve the overall safety and reliability of the circuit breaker.

Wide application range:

the product series has a wide application range, rated currents from 630A to 5000A, and rated breaking currents from 20kA to 50kA. It is suitable for all environments within an altitude of 4500 meters and an operating temperatures from -40°C to 40°C.

Supports intelligent customization:

a. A self-powered wireless temperature monitoring solution can be added to continuously monitor the temperature of key components, helping detect abnormal temperature rises in time while ensuring safe and reliable operation with reduced maintenance requirements.

b. A mechanical characteristic monitoring solution can be configured to continuously collect circuit breaker operating parameters and mechanical operation data, helping identify potential problems early and enabling timely fault warning and condition-based maintenance.

c. A motorized cabinet entry and withdrawal solution can be configured to support remote operation of the circuit breaker, reducing the need for personnel to directly approach high-voltage equipment and improving both operational convenience and personnel safety.

d. Partial discharge testing enables real-time detection of insulation component aging and abnormal discharge conditions, helping identify potential insulation defects at an early stage and reducing the risk of equipment failure.