The ZN23-40.5 is a three-phase 50 Hz handcart (withdrawable, center-mounted) indoor high voltage vacuum circuit breaker rated 40.5 kV, used to control and protect power plants, substations and industrial and mining distribution systems. Thanks to vacuum interruption it is especially suitable for frequent operation, such as metallurgy and electric-arc steel-making.
It is driven by a spring energy-storage mechanism charged from an AC or DC 220 / 110 V supply or manually, and racks between the connected, test and disconnected positions of metal-enclosed switchgear for safe isolation. Rated current is 1250, 1600 or 2000 A with a rated short-circuit breaking current of 25 or 31.5 kA, a 4 s short-time withstand rating and a 630 A capacitor bank breaking current.
Model Designation
The type is marked as ZN 23-40.5 C / □ – □:
- Z — vacuum
- N — indoor use
- 23 — design number
- 40.5 — rated voltage kV
- C — handcart (withdrawable) type
- / □ — rated current A
- – □ — rated short-circuit breaking current kA
Example: ZN23-40.5C/2000-31.5 denotes a 40.5 kV handcart indoor vacuum circuit breaker with 2000 A rated current and 31.5 kA rated short-circuit breaking current.
Performance Advantages
- 40.5 kV solid vacuum interruption. The arc is extinguished in a sealed vacuum interrupter, giving a high insulation level (185 kV impulse / 95 kV power frequency), a long electric life and no fire or explosion risk.
- Spring energy-storage mechanism. Stored-energy closing charged from AC or DC 220 / 110 V or manually, with a charging time under 15 s and reliable mechanical interlocking, suited to frequent operation.
- Handcart / withdrawable unit. The handcart structure racks between connected, test and disconnected positions of metal-enclosed switchgear, allowing fast isolation and replacement while the cubicle stays energised.
Technical Parameters
Service Conditions
- Ambient temperature: upper +40℃, lower -40℃
- Altitude: not above 1000 m (higher altitude raises the rated insulation level accordingly)
- Seismic intensity: not above intensity 8
- Humidity: daily average ≤ 95%, monthly average ≤ 90%
- Environment: no fire, explosion, serious pollution, chemical corrosion or violent vibration
Main Technical Parameters
| No. | Item | Unit | Data |
|---|---|---|---|
| 1 | Rated voltage | kV | 40.5 |
| 2 | Rated lightning impulse withstand voltage (peak) | kV | 185 |
| 3 | 1 min power-frequency withstand voltage | kV | 95 |
| 4 | Rated frequency | Hz | 50 |
| 5 | Rated current | A | 1250 / 1600 / 2000 |
| 6 | Rated short-circuit breaking current | kA | 25 / 31.5 |
| 7 | Rated short-time withstand current | kA | 25 / 31.5 |
| 8 | Rated peak withstand current | kA | 63 / 80 |
| 9 | Rated short-circuit duration | s | 4 |
| 10 | Rated short-circuit breaking time | ms | ≈ 90 |
| 11 | Rated short-circuit making current (peak) | kA | 63 / 80 |
| 12 | Rated operating sequence | — | O – 0.3 s – CO – 180 s – CO |
| 13 | Closing time | ms | 50 – 85 |
| 14 | Opening time | ms | 40 – 85 |
| 15 | Breaking operations at rated short-circuit current | times | 20 |
| 16 | Mechanical life | operations | 10000 |
| 17 | Rated capacitor bank breaking current | A | 630 |
| 18 | Energy-storage motor rated power | W | 275 |
| 19 | Energy-storage motor rated voltage | V | AC/DC 220, 110 |
| 20 | Energy-storage time | s | < 15 |
| 21 | Closing / opening solenoid rated voltage | V | AC/DC 220, 110 |
| 22 | Overcurrent release rated current | A | 5 |
| 23 | Auxiliary switch rated current | A | 10 |
Standards
- Designed and tested to GB/T 1984 (AC high-voltage circuit breakers) and IEC 62271-100
- Manufacturing and inspection per DL/T 403 (indoor high-voltage vacuum circuit breakers 3.6 to 40.5 kV)
Installation & Wiring
Installation and Mounting
The ZN23-40.5 is a handcart (withdrawable) breaker for 40.5 kV metal-enclosed switchgear. The breaker is assembled onto a chassis that racks between the connected, test and disconnected positions, so it can be isolated or removed without de-energising the cubicle. The primary circuit connects to the busbar through the static contacts of the chassis, and the secondary circuit is wired to the control, protection and measurement loops through the terminal block. The breaker frame and the switchgear body must be reliably earthed before commissioning, and all mechanical interlocks must be verified before operation.
Outline and Installation Dimensions
Main outline dimensions (mm) of the handcart unit are summarised below; refer to the approved outline drawing supplied with each order for the full dimension set.
| Outline dimension | Value (mm) |
|---|---|
| Overall width | 1410 |
| Overall height | 1690 |
| Upper section height | 750 |
| Lower section height | 861 |
Applications
- Indoor 40.5 kV MV switchgear in power plants, substations and industrial / mining distribution
- Control and protection of feeder and transformer circuits requiring frequent operation
- Metallurgy, electric-arc steel-making and other heavy, frequently switched loads
Selection & FAQs
Selection Guide
- Rated voltage and insulation level. Choose 40.5 kV for the nominal system voltage and check that the 185 kV impulse and 95 kV power-frequency withstand levels match the busbar insulation.
- Rated current. Select 1250, 1600 or 2000 A by the maximum continuous load current, considering temperature rise and chassis fit.
- Rated short-circuit breaking current. Select 25 or 31.5 kA by the prospective short-circuit current at the installation point, with the 4 s short-time rating.
- Operating mechanism. Spring energy-storage mechanism with AC/DC 220 / 110 V charging is standard; confirm the control supply when ordering.
- Mounting. Handcart (withdrawable) unit for metal-enclosed switchgear; specify the matching cubicle and chassis.
- Compare neighbouring designs. For outdoor applications see Outdoor Vacuum Circuit Breakers; for switching without short-circuit duty see HV Load Break Switches.
FAQs
Q1: What does the type designation ZN23-40.5C mean?
Z denotes a vacuum breaker, N indoor use, 23 the design number and 40.5 the rated voltage in kV; C indicates the handcart (withdrawable) type, and the two following boxes give rated current in amperes and rated short-circuit breaking current in kiloamperes.
Q2: What operating mechanism does the ZN23-40.5 use?
A spring energy-storage mechanism charged from an AC or DC 220 / 110 V supply or manually, with a charging time under 15 s, giving stored-energy closing and reliable mechanical interlocking.
Q3: What is the insulation level of the 40.5 kV breaker?
The rated lightning impulse withstand voltage is 185 kV (peak) and the 1 min power-frequency withstand voltage is 95 kV, the standard levels for 40.5 kV indoor switchgear.
Q4: Which rated currents and breaking currents are available?
Rated current is offered in 1250, 1600 and 2000 A, with a rated short-circuit breaking current of 25 or 31.5 kA, a short-time withstand of 25 or 31.5 kA for 4 s and a peak withstand and making current of 63 or 80 kA.
Q5: Is it suitable for frequent operation?
Yes. Vacuum interruption gives a long electric life and the mechanism a mechanical life of 10000 operations, so the breaker suits frequently switched loads such as metallurgy and electric-arc steel-making; it also breaks capacitor bank currents up to 630 A.
Q6: What data do I need to provide when ordering?
Please state rated voltage, rated current, rated short-circuit breaking current, short-time duration, control / charging supply voltage, the switchgear cubicle and chassis type, and any special service conditions.