The National Grid

• Describe the National Grid as an interconnected system of cables and transformers that links power stations to consumers.
• Explain the role of the National Grid in transferring electrical power from power stations to domestic and industrial users.
• Understand the function of step-up transformers in increasing the potential difference from the power station to the transmission cables.
• Understand the function of step-down transformers in decreasing the potential difference to a much lower, safer value for domestic use.
• Explain why the National Grid system is highly efficient for transferring electrical energy over long distances.
• (HT only) Select and apply the transformer equation to calculate potential difference or current in primary and secondary coils:

$V_p I_p = V_s I_s$