Losses in electricity transmission and distribution (T&D) are an inevitable part of the power delivery process. They are typically categorized into two main types: technical losses and non-technical losses.

1. Technical Losses: These are the losses inherent to the physical characteristics of the electrical network. They are caused by the resistance and reactance of components like conductors, transformers, and other equipment.

   • Resistive Losses: Also known as I2R losses or copper losses, this is the most significant type of technical loss. As current (I) flows through a conductor with resistance (R), some energy is converted into heat. This is why high-voltage transmission is used—it lowers the current and, because losses are proportional to the square of the current, dramatically reduces energy waste.

   • Transformer Losses: Transformers experience two types of losses: "no-load" losses (hysteresis and eddy current losses in the core) which occur whenever the transformer is energized, and "load" losses (I2R losses in the windings) which depend on the current flow.

   • Corona Losses: In high-voltage overhead lines, the electric field can ionize the air around the conductors, causing a visible glow, hissing sound, and energy loss.

2. Non-Technical Losses: These are losses that are not due to the physics of the grid but rather to administrative or human factors. They are also known as "commercial losses" or "non-metered energy."

   • Electricity Theft: Illegal connections or meter tampering.

   • Billing and Metering Errors: Inaccuracies in reading meters, faulty meters, or incorrect billing.

Minimizing both types of losses is crucial for improving grid efficiency and reducing costs.