ZN28-12 Series Indoor High Voltage Vacuum Circuit Breaker

Our ZN28-12 indoor vacuum circuit breakers deliver reliable protection for 12kV systems with flexible integrated or separate mounting options, compatible with CD17, CD10A electromagnetic, and CT17, CT19 spring mechanisms.

• Rated at 12kV with current up to 3150A; short-circuit breaking up to 40kA with making current up to 100kA.

• Mechanical life of 10,000 operations with 20–30 short-circuit breaking operations.

• Main circuit resistance ≤50μΩ (≤35μΩ for 40kA); contact gap of 11±1mm with overtravel of 4±1mm.

• Opening time ≤0.06s at max voltage, ≤0.08s at min voltage; closing time ≤0.1s with three-phase asynchrony ≤2ms.

• Contact closing bounce time ≤2ms; average opening speed of 1.2±0.3m/s for reliable fault clearing.

• Fast delivery, reliable quality, responsive service, and extensive project experience backed by our company.

Product Overview

The ZN28-12 series vacuum circuit breaker is an indoor high-voltage switching device with a rated voltage of 12kV and a three-phase AC 50Hz. The product complies with the GB1984-89 standard. It is available in two general structural configurations: integrated installation of the switch main body and the operating mechanism, and separate installation of the switch main body and the operating mechanism. The integrated structure is the ZN28-12 basic type; the separate structure is the ZN28-12 type, suitable for fixed-type switchgear such as GG-1A(Z), XGN2A10(Z), etc.

This product can be equipped with CD17, CD10A type DC electromagnetic operating mechanisms and CT17, CT19 type spring-stored energy operating mechanisms.

Technical Specifications

S.Q	Item		Unit	20kA	25kA	31.5kA	40kA
1	Rated Voltage		kV	12
2	Rated Current		A	630,1000 1250	1250 1600	1250,1600 2000,2500	1600,2500 3150
3	Rated Short-Circuit Breaking Current		kA	20	25	31.5	40
4	Rated Short-Circuit Making Current (Peak)		kA	50	63	80	100
5	Rated Peak Withstand Current		kA	50	63	80	100
6	Rated Short-Time Withstand Current for 4s		kA	20	25	31.5	40
7	Rated Insulation Level	Power Frequency Withstand Voltage (Before & After Rated Breaking)	kV	Power Frequency Withstand Voltage: 42kV (Phase-to-Phase), 48kV (Across the Breaker)
		Impulse Withstand Voltage (Before & After Rated Breaking)		Lightning Impulse Withstand Voltage: 75kV (Phase-to-Phase), 85kV (Across the Breaker)
8	Rated Operating Sequence			Operating Sequence: O-0.3s-CO-180s-CO
9	Mechanical Life		times	10000
10	Rated Number of Short-Circuit Breaking Operations		times	30	30	30	20
11	Operating Mechanism Rated Closing Voltage		V	110,220	110,220
12	Operating Mechanism Rated Closing Current		A	71	71	71	128
13	Operating Mechanism Rated Opening Voltage		V	AC/DC110,220
14	Operating Mechanism Rated Opening Current		A	3.01.5
15	Contact Gap		mm	11±1
16	Overtravel (Contact Spring Compression Length)		mm	4±1
17	Three-Phase Opening & Closing Asynchrony		ms	≤2
18	Contact Closing Bounce Time		ms	≤2
19	Average Opening Speed (At Initial 6mm Opening)		m/s	1.2±0.3
20	Average Closing Speed		m/s	0.6±0.2
21	Opening Time	At Maximum Operating Voltage	S	≤0.06
22	Rated Operating Sequence	At Minimum Operating Voltage		≤0.08
24	Closing Time		S	≤0.1
25	Main Circuit Resistance per Pole		μΩ	≤50	≤50	≤50	≤35
26	Permissible Cumulative Wear Thickness of Moving and Fixed Contacts		mm	3
27	Oil Buffer Stroke		mm	10

Normal Service Conditions

1. Ambient air temperature: not exceeding +40°C, lower limit -25°C.

2. Altitude: not exceeding 2000 m.

3. Humidity: Daily average relative humidity not more than 95%, monthly average not more than 90%; Daily average water vapor pressure not more than 2.2 kPa, monthly average not more than 1.8 kPa.

4. The ambient air shall not be significantly polluted by corrosive or flammable gases or water vapor.

5. No frequent severe vibration.

6. The inclination angle between the mounting plane and horizontal shall not exceed 5° during contactor operation.

7. Requirements beyond the above conditions shall be agreed upon between the user and the manufacturer.

Model and Its Meaning

□: Rated Short-Circuit Breaking Current (kA)

□: Rated Current (A)

12-: Rated Voltage (kV)/A: Separate Type

□: Integrated Type

28-: Design Serial Number

N-: Indoor

Z-: Vacuum Circuit Breaker

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