A step-up transformer is used at power stations to increase the voltage of the electrical energy generated, enabling efficient transmission over long distances. The primary functions and advantages of using a step-up transformer include:

1. **Voltage Increase**: Power stations typically generate electricity at lower voltages (e.g., 11 kV). A step-up transformer raises this voltage to higher levels (e.g., 132 kV or 220 kV). Higher voltage reduces the current for the same power transmission, as given by the formula \( P = V \times I \) (where \( P \) is power, \( V \) is voltage, and \( I \) is current).

2. **Reduced Losses**: By increasing the voltage, the current in the transmission lines decreases. This reduction in current minimizes resistive losses (I²R losses) in the transmission lines, which can be significant over long distances. For example, if the transmission line resistance is high, a high current would lead to greater energy loss as heat.

3. **Long-Distance Transmission**: Higher voltage allows electricity to be transmitted over much longer distances without significant losses. This is crucial for connecting remote power generation sites (like wind farms or hydroelectric plants) to urban areas where electricity is consumed.

### Example:

For instance, a power station generating 11 kV of electricity may utilize a step-up transformer to increase the voltage to 220 kV. This high-voltage electricity can then be transmitted through the national grid to various substations, where it is stepped down again for distribution to homes and businesses.

In summary, a step-up transformer plays a vital role in enhancing the efficiency and reliability of the electrical power transmission system, ensuring that electricity generated in remote locations can effectively reach consumers with minimal losses.