The ZN63(VS1)-24 is a three-phase 50 Hz handcart (center-mounted) indoor high voltage vacuum circuit breaker rated 24 kV, used as the control and protection unit of power plants, substations and industrial and mining distribution systems. Owing to the advantages of vacuum interruption it is especially suitable for interrupting important loads and for frequent operation, including at high altitude.
The standard operating mechanism is a spring energy-storage type that can be charged from AC or DC 220 / 110 V control supply or manually; a long-life permanent-magnet operating mechanism with a mechanical life of up to 60000 operations is available for extremely frequent duty. The breaker is built in a front-to-back split structure that can be used either as a fixed mounting unit or racked on a chassis as a center-mounted unit of metal-enclosed switchgear, with reliable mechanical interlocking.
Model Designation
The type is marked as ZN 63-24 / □ – □:
- Z — vacuum
- N — indoor use
- 63 — design number
- 24 — rated voltage kV
- / □ — rated current A
- – □ — rated short-circuit breaking current kA
Example: ZN63(VS1)-24 / 1250 – 25 denotes a 24 kV indoor vacuum circuit breaker with 1250 A rated current and 25 kA rated short-circuit breaking current. ZN63 is the GB type designation of this series; VS1 is the equivalent common trade name.
Performance Advantages
- Spring energy-storage mechanism. Stored-energy closing with AC or DC 220 / 110 V or manual charging and reliable interlocking; an optional permanent-magnet mechanism raises the mechanical life to 60000 operations for very frequent duty.
- Interrupting medium. The arc is extinguished in a sealed vacuum interrupter, giving a long electric life, no fire or explosion risk and no frequent overhaul.
- Handcart / center-mounted unit. The front-to-back split structure can be racked out for isolation as a center-mounted unit or used as a fixed mounting unit within metal-enclosed switchgear.
Key Ratings Snapshot
| Item | Value |
|---|---|
| Rated voltage | 24 kV |
| Rated frequency | 50 Hz |
| Rated current | 630–1600 A |
| Rated short-circuit breaking current | 20 / 25 / 31.5 kA |
| Mechanical life | 20000 operations (60000 with permanent-magnet mechanism) |
| Standard | GB/T 1984 / DL/T 403 / IEC 62271-100 |
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
Current and Breaking Ratings
| Item | Unit | 20 kA | 25 kA | 31.5 kA |
|---|---|---|---|---|
| Rated current | A | 630 | 1250 | 1600 |
| Rated short-circuit breaking current | kA | 20 | 25 | 31.5 |
| Rated short-circuit making current (peak) | kA | 50 | 63 | 80 |
| Rated short-time withstand current (4 s) | kA | 20 | 25 | 31.5 |
Main Technical Parameters
| No. | Item | Unit | Data |
|---|---|---|---|
| 1 | Rated voltage | kV | 24 |
| 2 | Rated frequency | Hz | 50 |
| 3 | Rated current | A | 630 / 1250 / 1600 |
| 4 | Rated short-circuit breaking current | kA | 20 / 25 / 31.5 |
| 5 | Rated short-circuit making current (peak) | kA | 50 / 63 / 80 |
| 6 | Rated short-time duration | s | 4 |
| 7 | Breaking operations at rated short-circuit current | times | 20 |
| 8 | Rated operating sequence | — | O – 0.3 s – CO – 180 s – CO |
| 9 | Lightning impulse withstand voltage (across open contacts) | kV | 125 |
| 10 | 1 min power-frequency withstand voltage (across open contacts) | kV | 65 |
| 11 | Closing time | ms | ≤ 100 |
| 12 | Opening time | ms | ≤ 50 |
| 13 | Mechanical life | operations | 20000 (60000 with permanent-magnet mechanism) |
| 14 | Rated energy-storage and operating voltage | V | AC/DC 220, 110 |
| 15 | Breaking (total) time | ms | ≤ 65 |
| 16 | Energy-storage time | s | ≤ 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 ZN63(VS1)-24 is a handcart (center-mounted) breaker for metal-enclosed switchgear. The front-to-back split structure allows the breaker to be used either as a fixed mounting unit or assembled onto a chassis as a center-mounted (racked) unit; in the racked form the breaker can be moved between the connected, test and disconnected positions for safe isolation. The primary circuit is connected to the busbar through the static contacts or cable lugs, and the secondary circuit is wired to the control and protection loop through the terminal block. The breaker and its frame must be reliably earthed before commissioning.
Outline and Installation Dimensions
The series is offered in two frame sizes matched to the switchgear cubicle — a 1250 A unit for 800 mm-wide cubicles and a 2000 to 3150 A unit for 1000 mm-wide cubicles. Main outline dimensions (mm) are summarised below; refer to the approved outline drawing supplied with each order for the full dimension set.
| Outline dimension (mm) | 1250 A · 800 cubicle | 2000–3150 A · 1000 cubicle |
|---|---|---|
| Overall height (side view) | 806 | 806 |
| Front frame width | 638 | 838 |
| Front panel width | 650 | 852 |
| Front base width | 681 | 881 |
| Handcart base length (side view) | 444 ± 2 | 730 |
| Lower bracket width (side view) | 459 | 458 |
| Pole spacing (vertical) | 310 | 310 |
Applications
- Indoor 24 kV MV switchgear in power plants, substations and industrial / mining distribution
- Feeder and transformer protection and control requiring frequent operation
- High-altitude installations interrupting important loads
Selection & FAQs
Selection Guide
- Rated voltage and insulation level. Choose 24 kV for the nominal system voltage and check that the power-frequency and impulse withstand levels match the busbar insulation.
- Rated current. Select 630, 1250 or 1600 A by the maximum load current, considering temperature rise and busbar fit.
- Rated short-circuit breaking current. Select 20 / 25 / 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 is standard; specify the permanent-magnet mechanism where very frequent operation and a longer mechanical life (up to 60000 operations) are required.
- Mounting. Handcart / center-mounted unit for metal-enclosed switchgear, or fixed mounting using the split structure.
- 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 ZN63-24 mean?
Z denotes a vacuum breaker, N indoor use, 63 the design number and 24 the rated voltage in kV; the two following boxes give rated current in amperes and rated short-circuit breaking current in kiloamperes. ZN63 is the GB type code and VS1 the equivalent common trade name.
Q2: What operating mechanism does the ZN63(VS1)-24 use?
The standard mechanism is a spring energy-storage type charged from AC or DC 220 / 110 V or manually, giving stored-energy closing and reliable interlocking. A long-life permanent-magnet mechanism is available as an option for extremely frequent operation.
Q3: What is the mechanical life of the breaker?
The spring-mechanism breaker has a mechanical life of 20000 operations; with the optional permanent-magnet mechanism the mechanical life reaches 60000 operations for very frequent duty.
Q4: Is it a handcart or a fixed breaker?
Both. The front-to-back split structure allows the breaker to be racked on a chassis as a center-mounted unit that can be moved to a disconnected position for isolation, or installed as a fixed mounting unit.
Q5: How do I choose the rated short-circuit breaking current?
Calculate the prospective three-phase short-circuit current at the installation point and select 20, 25 or 31.5 kA to cover it, checking that the making and short-time withstand currents of 50 / 63 / 80 kA and 4 s are also satisfied.
Q6: What data do I need to provide when ordering?
Please state rated voltage, rated current, rated short-circuit breaking current, short-time duration, operating mechanism (spring or permanent-magnet), the switchgear cubicle width and whether a racked or fixed unit is required, and any special service conditions.