33KV Electrical Joint Box Cable Distribution Switchgear

Cotenele is one of the well-known electrical equipment manufacturers in China,Our 33KV Electrical Joint Box Cable Distribution Switchgear is a widely used outdoor or indoor power distribution device in 33kV transmission and distribution networks. Its primary function is to enable branching, transferring, and combining of electrical energy in cable lines, as well as (in specific models) line segmentation and control.In high-voltage power systems, it serves as a nodal point for cable lines, distributing incoming power from one main line to multiple outgoing lines, thereby extending the power supply radius, reducing overall project costs, and improving supply flexibility and reliability.

Main technical parameters

Product working principle

The operation principle of the 33KV Electrical Joint Box Cable Distribution Switchgear is based on the current division action of parallel circuits.  

1. Power input: High voltage cables introduce electrical energy through incoming accessories and supply the incoming terminals of busbars (copper bars) or SF6 switches inside the box.  

2. Busbar collection: Electric energy is collected on the three-phase busbar inside the box.  

3. Branch output: Multiple outgoing cables are simultaneously connected to the same phase busbar through cable fittings (basic type), or led out from the outgoing side of the switch (switch type).  

4. Protection and monitoring: During operation, the lightning arrester suppresses overvoltage in real time; Voltage indicator and (optional) fault indicator are used to monitor the status of the circuit. If equipped with a load isolation switch, the circuit can be disconnected during maintenance, forming a clear isolation point.

The working scope of the 33KV Electrical Joint Box Cable Distribution Switchgear

The 33kV voltage level determines that this equipment is mainly used in large power distribution systerm:

• Urban Core Distribution Networks: As a supplement to the 33kV ring main box, the 33KV Electrical Joint Box is commonly used as a cable distribution network node in busy streets and commercial centers, reducing land occupation.
• Industrial and Mining Enterprises: In some large factories, users can also distribute the power from the main 33kV substation to the substations in each workshop through 33kV cable branch boxes.
• Renewable Energy Plants:

1. Wind Power: In wind power plants, 33KV Electrical Joint Boxes are used to connect the collection lines of multiple wind turbines.
2. Solar PV: In large photovoltaic power plants, the medium voltage cable branch box is used to connect the 33kV box type transformer and the lines between them, and to connect to the step-up substation.

• Transportation and Infrastructure: 33kV cable branch boxes are also used as intermediate transfer and distribution points for long-distance cable lines in power systems for infrastructure construction such as highways, tunnels, and airports.

Usage Precautions for the 33KV Electrical  Joint Box  

1. Environmental Adaptability:

• At altitudes above 1000 meters, consider reduced external insulation strength; specify a plateau type design to the manufacturer.
• In high salt spray or high humidity area, the enclosure of the 33KV Electrical  Joint Box Cable Distribution Switchgear should be made of 316L stainless steel material, and the enclosure coating should be enhanced with anti-corrosion measures.

2. Waterproofing and Immersion Prevention:Although this cable branch box has a high level of protection, if there is water accumulation in the cable trench or foundation pit, it may cause the cable accessories to be soaked in water for a long time, which may lead to malfunctions. Therefore, it is necessary to ensure smooth drainage.

3. Prevent Misoperation: For 33KV Electrical Joint Box Cable Distribution Switchgear with load isolation switches, it is necessary to confirm the current status of the circuit before operation. please no to open or close disconnector when energized unless the switch is rated to disconnect the load.

4. Grounding Requirements: The enclosure of the 33KV Electrical  Joint Box Cable Distribution Switchgear  must be reliably grounded, and the grounding wire connection of the cable shielding layer must be correct and standardized,which is  to ensure personnel safety.

5. Moisture Prevention: For 33KV air-insulated Electrical  Joint Box Cable Distribution Switchgear  (exposed copper bars), heating and dehumidification devices must be installed to prevent creeping or short circuits caused by condensation.

How to Select the Right  Cable Distribution Switchgear?

Please confirm the following main technical parameters and configurations when  selecting:

1. Rated Voltage : The rated voltage of the Cable Distribution Switchgear must match the system nominal voltage of 33KV/35kV ( The maximum voltage is 40.5kV)

2. Rated Current: The rated current of the main busbar of a 33kV Cable Distribution Switchgear is usually 630A, but we should still selected the suitable current based on the actual load current. If need higher current, please communicate with the manufacturer first and customized the products according to your requirements.

3. Number of Circuits: Determine the required line configuration, such as one input and how many output lines or how many input and how many output lines.

4. Switch Required or Not:

• For pure cable branching with low operating frequency: choose a basic cable branching box.  
• For fault isolation, ring network power supply, or maintenance of isolation points: choose a load isolation switch type cable branch box.  

5. Insulation method: t is recommended to use a fully insulated and fully sealed European style cable branch box (using prefabricated silicone rubber or EPDM connectors) to ensure high safety and be suitable for outdoor use.  

6. Shell material: It is generally recommended to use stainless steel cable branch box shells for outdoor use. For highly corrosive area, need to choose  the 316 stainless steel shell.  

7. Additional function: Determine whether lightning arrester protection, fault indicator, or intelligent monitoring (DTU/FTU interface) is required for distribution automation.

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