How should a hotel's high-voltage power supply scheme be selected? What are the applicable conditions for 10kV versus 35kV?
I am electrical expert James Li, specializing in electrical system design and power supply and distribution. The question you raised is crucial in hotel project electrical design, because the choice of high-voltage power supply scheme directly affects power supply reliability, economy, and operational convenience. Typically, hotels, as Class I important loads (such as five-star hotels), require comprehensive decision-making based on local grid conditions, electrical load capacity, and investment budget. Below I will provide a detailed analysis combining standards and practice.
First, whether to choose a 10kV or 35kV power supply scheme must be based on Article 3.0.1 of GB 50052-2009 "Code for Design of Power Supply and Distribution Systems," which requires that the supply voltage be determined according to factors such as electrical load capacity, supply distance, current local grid conditions, and development planning. The specific applicable conditions are as follows:
- **10kV power supply**: Suitable for hotels with relatively small electrical load capacity (typically less than 10MVA) and short supply radius (generally no more than 20 km). For example, a medium-sized business hotel (total load of about 2000-4000kVA), if there is a 10kV substation nearby, can meet demand with direct 10kV supply. In a four-star hotel project I participated in (total load 3200kVA), two independent power sources were introduced from the municipal 10kV ring main unit, equipped with two 1600kVA dry-type transformers, and dual-source automatic transfer was achieved through 10kV high-voltage switchgear (such as KYN28-12 type). Operation was stable and investment moderate.
- **35kV power supply**: Suitable for hotels with relatively large electrical load capacity (typically exceeding 10MVA) or long supply distance (exceeding 20 km). For example, a large resort hotel (total load of about 15-20MVA), if far from the urban grid, can use 35kV to reduce line losses and voltage drop. I once handled a seaside resort hotel project (total load 18MVA). Because it was only 8 km from the nearest 35kV substation, a 35kV dual-circuit power supply was adopted, equipped with two 10MVA main transformers, and a 35/10kV step-down station was set up within the hotel, then distributed to substations in each zone. This complies with the principle in Article 3.0.2 of GB 50052 regarding bringing high voltage deep into the load center, reducing low-voltage distribution losses.
In actual engineering, it is also necessary to consider the voltage level specifications of the local grid (10kV is more common in many cities, while 35kV requires dedicated lines), as well as investment cost: 35kV equipment (such as transformers and switchgear) has higher initial investment, but long-term operating efficiency is better. For example, for a five-star hotel (total capacity 12MVA), comparing the two schemes: 10kV requires 4 incoming lines (3MVA each), while 35kV requires only 2, the latter saving the number of cables and switchgear, but requiring an additional 35kV distribution room.
In summary, the core basis for choosing 10kV or 35kV is the hotel's total electrical load capacity and supply distance: if less than 10MVA and the distance is short, 10kV is preferred; if greater than 10MVA or the distance is long, 35kV is recommended. Specifically, it must be determined through technical and economic comparison in combination with local grid planning and project budget.
The above are reference opinions. The actual project situation still needs further comprehensive evaluation and implementation in combination with specific operating conditions, site conditions, and other factors.