The safe transportation of SF6 circuit breakers is crucial, ensuring their safe arrival and smooth commissioning. Because they contain high-pressure SF6 gas and delicate insulation and arc-extinguishing components, strict transportation regulations must be adhered to.
The following are detailed guidelines and precautions for the safe transportation of SF6 circuit breakers:
Ⅰ. Pre-Transportation Preparation (Most Critical Step)
◆Gas Handling (Core Operation):
Vacuuming is mandatory: Transporting at rated pressure is strictly prohibited! The SF6 gas pressure inside a circuit breaker is typically as high as 0.4-0.6 MPa (approximately 4-6 atmospheres). The bumps and vibrations during transportation can loosen components and cause high-pressure gas leaks, which is extremely dangerous.
Standard Operation: Use a dedicated SF6 gas recovery device to completely recover the SF6 gas inside the circuit breaker into a gas storage tank and evacuate the internal space of the circuit breaker to a high vacuum (usually requiring a vacuum level below 133 Pa).
Filling with dry nitrogen: After evacuating, to prevent moisture intrusion and vibration of internal components during transportation, the circuit breaker is typically filled with dry, high-purity nitrogen (99.999% purity) at a pressure of 0.05-0.1 MPa. This slightly positive pressure of nitrogen maintains internal dryness and cushions vibrations.
◆Seal Inspection:
After evacuating the circuit breaker and filling it with low-pressure nitrogen, be sure to perform a leak inspection on all sealing surfaces, pipe joints, and valves to ensure the circuit breaker is properly sealed during transportation and prevent moisture intrusion.
◆Mechanism Status Verification:
Place the circuit breaker's operating mechanism (spring mechanism, hydraulic mechanism, etc.) in the "closed" or "open" position, unenergized (e.g., release the spring energy). Transporting the circuit breaker in the charged state is strictly prohibited to prevent malfunction or damage to the mechanism.
Turn off all power switches and disconnect all external electrical connections.
◆Packaging and Securing:
Original Packaging: Whenever possible, use the manufacturer's dedicated shipping packaging racks and securing devices. These packaging is specially designed to effectively protect the equipment.
Secure Securing: Securely secure the circuit breaker body and mechanism to the transport vehicle (truck or flatbed) using ropes, chains, or other means. Use non-slip mats to prevent slipping and tipping.
Vibration Control: Use shock-absorbing materials (such as wood or rubber mats) between the device and the transport platform to reduce vibration and impact.
Separate Transportation: Large, oversized SF6 circuit breakers typically require disassembly of the interrupter unit, support cylinder, and operating mechanism. Strictly follow the manufacturer's disassembly and transportation instructions, and protect all flange and sealing surfaces after disassembly.
II. Transportation Precautions
Vehicle Selection: Choose a flatbed truck or a vehicle with good shock absorption. The vehicle platform must be flat and sturdy, large enough to accommodate the equipment, and have sufficient anchorage points.
Speed Control: Drive steadily and at a low speed during transportation. Especially when encountering poor road conditions (such as rough roads, speed bumps, or potholes), reduce speed further and avoid sudden braking and violent jolts.
Height Limits: Pay attention to the transport height of the equipment, especially for circuit breakers with tall support columns and porcelain bottles. Be aware of height-restricted obstacles such as bridges, tunnels, and power lines along the way. For oversized equipment, apply for an oversized transportation permit from the traffic control department in advance and arrange for a guide vehicle if necessary.
Weather Protection: Cover the equipment with a rainproof tarpaulin during transportation to protect it from the sun and rain. In particular, prevent rain from entering the mechanism box and circuit breaker (even if it is nitrogen-filled, this precaution is still necessary).
Full-Time Monitoring: A dedicated person should accompany the vehicle to monitor critical equipment and regularly check for loose securing ropes and for any risk of displacement or collision.
III. Inspection after Arrival
Appearance Inspection: Before and after unloading, carefully inspect the equipment for external damage, especially cracks and breakage on the porcelain cylinder and any bumps or deformation on the outer casing.
Air Pressure Check: Immediately check the low-pressure nitrogen filling the circuit breaker for normal pressure and whether the pressure gauge reading is within the permitted range. If the pressure drops significantly, this indicates a possible leak and requires notification to the manufacturer.
Seal Check: Before refilling, it is best to perform a vacuum and seal test to ensure that the seal remains in place after transport.
Mechanical Inspection: Check all screws and connectors in the operating mechanism for looseness and ensure that they are in the same condition as before transport.
Summary
Key Points for Safe Transportation
High-pressure SF6 gas must not be transported.
Evacuate the equipment and fill it with low-pressure dry nitrogen.
The operating mechanism must be deenergized and in the open/closed position.
Original packaging or securely fastened by reliable means must be used.
Drive the equipment steadily and at a low speed to prevent vibration and impact.
Proper protection from rain and moisture must be ensured.
A thorough inspection must be carried out before and after transportation.
If you need further information, please feel free to ask. I will do my best to provide you with reference information based on general technical specifications.
Email:pannie@hdswitchgear.com
Whatsapp/Wechat:+8618789455087
