page_title: Performance and modelling of AC transmission
section_title: Surge impedance
hierarchical_section_title: Performance and modelling of AC transmission / Terminologies / Surge impedance
caption_attribution_description: English: Voltage in sending and receiving ends for lossless line
context_page_description: Performance modelling is the abstraction of a real system into a simplified representation to enable the prediction of performance. The creation of a model can provide insight into how a proposed or actual system will or does work. This can, however, point towards different things to people belonging to different fields of work.
  Performance modelling has many benefits, which includes:
  Relatively inexpensive prediction of future performance.
  A clearer understanding of a system's performance characteristics.
  Additionally it may include, a mechanism for risk management and reduction with design support for future projects.
  A model will often be created specifically so that it can be interpreted by a software tool that simulates the system's behaviour, based on the information contained in the performance model. Such tools provide further insight into the system's behaviour and can be used to identify bottlenecks or hot spots where the design is inadequate. Solutions to the problems identified might involve the provision of more physical resources or change in the structure of the design.
  Performance modelling is found helpful, in case of:
  Estimating the performance of a new system.
context_section_description: The characteristic impedance or surge impedance (usually written Z₀) of a uniform transmission line is the ratio of the amplitudes of voltage and current of a single wave propagating along the line; that is, a wave travelling in one direction in the absence of reflections in the other direction. Alternatively and equivalently it can be defined as the input impedance of a transmission line when its length is infinite. Characteristic impedance is determined by the geometry and materials of the transmission line and, for a uniform line, is not dependent on its length. The SI unit of characteristic impedance is Ohm (Ώ)
  Surge impedance determines the loading capability of the line and reflection coefficient of the current or voltage propagating waves.
  Where,
  Z₀ = Characteristic Impedance of the Line
  L = Inductance per unit length of the Line
  C = Capacitance per unit length of the Line
caption: Surge Impedance Loading on Losslessline
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