Application
The LW30-252 high-voltage sulfur hexafluoride (SF₆) circuit-breaker is a three-pole, AC 50Hz outdoor high-voltage switching device. It is primarily used for control and protection in 220kV power systems and can also be employed as a bus-tie or coupling circuit-breaker.
Technical Specifications
|
No. |
Item |
Unit |
Parameter |
|
|
1 |
Main technical parameters of the circuit breaker |
|||
|
1.1 |
Rated voltage |
kV |
252 |
|
|
1.2 |
Rated power frequency withstand voltage (1 min) |
To ground |
kV |
460 |
|
Between contacts |
kV |
460+146 |
||
|
1.3 |
Rated lightning impulse withstand voltage |
To ground |
kV |
1050 |
|
Between contacts |
kV |
1050+206 |
||
|
1.4 |
Rated frequency |
Hz |
50 |
|
|
1.5 |
Rated current |
A |
4000 |
|
|
1.6 |
First-break coefficient |
1.3 |
||
|
1.7 |
Rated short-circuit breaking current IK |
kA |
50 |
|
|
1.8 |
Rated short-circuit making current (peak value) |
kA |
125 |
|
|
1.9 |
Rated short-circuit withstand current |
kA |
50 |
|
|
1.10 |
Rated peak withstand current |
kA |
125 |
|
|
1.11 |
Rated short-circuit duration |
S |
3 |
|
|
1.12 |
Rated out-of-step breaking current |
kA |
12.5 |
|
|
1.13 |
Near-fault breaking current |
kA |
90%Ik ,75%Ik |
|
|
1.14 |
Rated line charging making and breaking current |
A |
200 |
|
|
1.15 |
Rated operating sequence |
O-0.3s-CO-180s-CO |
||
|
1.16 |
Main circuit resistance |
μΩ |
≤40 |
|
|
1.17 |
Rated SF6 gas pressure (gauge pressure at 20ºC) |
MPa |
0.6 |
|
|
1.18 |
Alarm/minimum functional pressure |
MPa |
0.55±0.015 |
|
|
1.19 |
SF6 gas annual leakage rate |
≤0.5% |
||
|
1.20 |
SF6 gas moisture content (V/V) |
ppm |
≤150 |
|
|
1.21 |
Mechanical life |
PCS |
10000 |
|
|
1.22 |
Creeage distance |
Between contacts |
mm |
≥8660 |
|
To ground |
mm |
≥6900 |
||
|
1.23 |
Mass of SF6 gas charged per unit |
kg |
23 |
|
|
1.24 |
Mass of the circuit breaker |
kg |
3300 |
|
|
2 |
Main technical parameters of the operating mechanism |
|||
|
2.1 |
Auxiliary circuit voltage |
V |
DC220V |
|
|
2.2 |
Opening and closing coil voltage/current |
V/A |
DC220V |
|
|
2.3 |
Energy storage motor |
Rated voltage |
V |
AC/DC220 |
|
Normal operating voltage range |
V |
85%～110% |
||
|
Power |
W |
720 |
||
|
2.4 |
Motor energy storage time |
S |
≤20 |
|
|
2.5 |
Heater and lighting circuit voltage |
V |
AC220 |
|
|
2.6 |
Rated voltage of auxiliary switch |
V |
DC220 or AC220 |
|
|
2.7 |
Rated current of auxiliary switch |
A |
10 |
|
|
2.8 |
Number of auxiliary switch contacts |
11 normally open |
||
|
3 |
Mechanical adjustment parameters of the product |
|||
|
3.1 |
Inter-pole center distance of the circuit breaker |
mm |
2800～4000 |
|
|
3.2 |
Travel of the moving contact |
mm |
160±3 |
|
|
3.3 |
Contact travel of the moving contact |
mm |
50±2 |
|
|
3.4 |
Opening time |
ms |
30±5 |
|
|
3.5 |
Closing time |
ms |
90±12 |
|
|
3.6 |
Breaking time |
ms |
≤60 |
|
|
3.7 |
Close-open time |
ms |
70 |
|
|
3.8 |
Open-close time |
ms |
300 |
|
|
3.9 |
Asynchronism of three-phase opening |
ms |
≤3 |
|
|
3.10 |
Asynchronism of three-phase closing |
ms |
≤4 |
|
Type Designation and Its Meaning
| L: SF₆ Circuit-Breaker | W: Outdoor | 30: Design Serial Number | 252: Rated Voltage (kV) |
Environmental Conditions
- Daily temperature variation: ≤25 °C
- Solar radiation: 0.1 W/cm²
- Relative humidity: Daily average ≤95%; Monthly average ≤90%
- Wind velocity: 34 m/s
- Seismic withstand capability: Horizontal acceleration 0.250g; Vertical acceleration 0.125g
- Pollution level: Class III (25mm/kV), Class IV (31mm/kV)
- Ice coating thickness: 10 mm (at wind velocity ≤15m/s)
- Degree of protection: IP5XW
Main Features
| 1. High self-energy arc-extinguishing and interrupting capability. | 2. Simple structure. | 3. Utilizes an extended nozzle; materials incorporate new fillers. |
| 4. Long electrical endurance. | 5. High current-carrying capacity. | 6. Excellent insulation performance. |
| 7. Reliable sealing structure. | 8. Low radio interference voltage (RIV). | 9. Low operating noise. |
| 10. Operating mechanism is free from oil permeation and gas leakage. | 11. Convenient field installation. | 12. Minimal maintenance requirements. |
Product Structure
The LW30-252 high-voltage SF₆ circuit-breaker features a three-pole porcelain column structure, with each pole being a single-column, single-break arrangement in an I-type configuration. Each pole is equipped with a CT spring operating mechanism mounted on the side of the base frame. The base frame contains the SF₆ gas piping and transmission linkages. The three poles are electrically linked for simultaneous operation.
The circuit-breaker uses SF₆ gas as both the arc-extinguishing and insulating medium, employing the self-energy arc-extinguishing principle. Each pole has an independent SF₆ gas system, and its pressure and density are monitored by an SF₆ density relay.
The interruptor (arc-extinguishing chamber) assembly, the core component of the breaker, is installed inside the interruptor porcelain housing. It mainly consists of the interruptor cover, stationary arcing contact holder, stationary main contact, stationary arcing contact, nozzle, moving arcing contact, puffer cylinder, moving main contact, intermediate contact, piston, and lower support seat. The permanent current-carrying circuit is formed by the upper terminal pad, stationary contact holder, stationary main contact, moving main contact, puffer cylinder, intermediate contact, lower support seat, and lower terminal pad.
The circuit-breaker is equipped with a motor-charged spring operating mechanism housed within the mechanism box. The mechanism box and the framework are fixed onto a concrete foundation. The single-pole interruptor is mounted atop the mechanism box.
List of Components
| 1. Closing solenoid | 2. Closing trigger | 3. Manual closing button | 4. Anti-closing latch pin | 5. Closing latch | 6. Pin B |
| 7. Closing spring | 8. Ratchet wheel | 9. Opening spring | 10. Camshaft | 11. Cam | 12. Crank arm shaft B |
| 13. Pawl shaft | 14. Pawl | 15. Crank arm shaft A | 16. Pin A | 17. Closing holding latch | 18. Anti-opening latch pin |
| 19. Opening trigger | 20. Opening solenoid | 21. Manual opening button | 22. Anti-pumping latch pin |
I. Crank arm A
II. Crank arm B
a) Circuit-breaker in closed position (closing spring charged)
b) Circuit-breaker in closed position (closing spring charged)
c) Circuit-breaker in closed position (closing spring discharged)
Operating Principle
The interruptor primarily utilizes the self-energy thermal expansion principle, combined with the puffer-type arc extinguishing principle, featuring a variable contact gap and a double-nozzle structure. During the interruption of a short-circuit current, the moving and stationary main contacts separate first, transferring the current to the stationary arcing contact mounted on the stationary contact holder and the moving arcing contact mounted on the puffer cylinder. An arc is drawn upon separation of the moving and stationary arcing contacts. After the stationary arcing contact leaves the nozzle, the arc's blocking effect is utilized. Simultaneously, the thermal expansion of the SF₆ gas heated by the arc causes a continuous pressure rise in the upstream region and inside the puffer cylinder. This results in an extremely high gas blast pressure within the interruptor, directed at the arc. This action increases the dielectric recovery strength across the contacts at current zero, thereby extinguishing the arc.
Closing Operation
Upon receiving a closing command, the closing release coil trips the closing latch. The closing spring releases its stored energy, driving the cam to rotate. During its rotation, the cam profile engages and rotates the main crank arm, which in turn drives the output lever to perform the closing operation. During closing, the opening spring is charged via the operating linkage. After closing is completed, the main crank arm is held by the opening latch, placing the circuit-breaker in the closed position ready for opening.
Immediately after releasing its energy, the closing spring is recharged automatically within 15 seconds. Mechanical and electrical interlocks prevent re-closing of the operating mechanism during this period. The circuit-breaker is now in the closed and spring-charged state.
Opening Operation
Upon receiving an opening command, the opening release coil trips the opening latch. The moving parts within the interruptor are driven downwards by the force of the opening spring. As the opening stroke nears its end, the oil buffer inside the mechanism becomes effective, absorbing the kinetic energy of the opening operation.
Ordering Information
The following information must be specified when placing an order:
Circuit-breaker type designation.
Rated electrical parameters: voltage, current.
Service environmental conditions.
Control supply voltage.
Primary terminal connection direction.
Name and quantity of required spare parts, accessories, special tools, and special equipment.
Any special requirements should be explicitly stated to avoid supply errors.
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