21 November 2011

Voltage and Frequency operating range (tolerance) of Grid Supply in India

Frequency variation in the power system exists due to the mismatch between the supply of power and demand for the power. Voltage variations exist in the power grid is due to the mismatch in the reactive power between demand (MVAR) and available.
In spite of all these variations there is certain limit for the operation limits (variations allowed) for voltage and frequency parameters dictated by the Grid Code. Any variations in the parameters (voltage and frequency) below operating limits considered as power grid is unhealthy and restoration steps will be taken to make the power grid healthy.
In India according to Electricity Grid Code, the operation variation in the frequency and voltage allowed is given as below.

Frequency Operating variation limits:

 49Hz  to 50.5 Hz

Voltage operating variation limit:

Voltage Rating          Maximum Voltage             Minimum Voltage
  400 kV                       420 kV                                360 kV
  220 kV                       245 kV                                200 kV
  132 kV                       145 kV                                120 kV

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