Gas Insulated Switchgear

High speed earthing switch (HSGS) rated operating sequence according to IEC standard (for>550kv)

HSES have two kind rated operating sequence:
➊C–ti1– O
➋C–ti1–O–ti2–C–ti1–O
where
➤ti1 is a time that is longer than the time required for secondary arc extinction and for dielectric recovery of air insulation at the faulted point. ti1 is determined by users
considering system stability. The preferred value of ti1 is 0,15 s.
➤ti2 is the intermediate time that is given by the system protection. ti2 includes the closing time of the circuit breakers after the HSESs open, the duration of a new line fault and the breaking time of the circuit breakers.
Following this ti2 time, the HSES can be reclosed.
The preferred value of ti2 is 0,5 s;
In this case the HSES shall be able to operate without intentional time delay.
Figure shows the time chart for the rated operating sequence of C–ti1–O–ti2– C–ti1–O with CB in grid.

In figure shown:

  1. Energizing of the closing circuit of the HSESs
  2. Current start in HSESs
  3. Contact touch of HSESs
  4. Energizing of the opening release of the HSESs
  5. Contact separation of HSESs
  6. Arc extinction in HSESs
  7. Fully open position of HSESs

The HSES closing time is normally less than 0,2 s

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Source
IEC

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