The highest voltage levels (in kV, or kilovolts) depend on the application. Here are some examples of extremely high voltages:
1. **Electric Power Transmission**:
- The highest transmission voltages used in the world are **1,100 kV** (1.1 million volts). This voltage is used in some long-distance, high-efficiency transmission lines, such as those in China.
2. **High Voltage Direct Current (HVDC)**:
- HVDC systems also use very high voltages, with some reaching up to **800 kV** for overhead lines and even higher for underground cables (e.g., 1,100 kV for specific projects).
3. **Scientific Research**:
- For particle accelerators and scientific experiments, voltages can go into the range of several million volts (MV). For example, **10 MV** or more are used in accelerators like the **Large Hadron Collider (LHC)**.
4. **Electrical Equipment**:
- Large electrical transformers and circuit breakers can handle voltages in the range of **300 kV to 800 kV**.
In short, **1,100 kV** is one of the highest voltages used in commercial power transmission. However, voltages in the millions of volts are used in specialized fields like scientific research and certain types of equipment.