It depends on the time of the breach and the quantum of fall. Trade could be halted for 15 minutes up to the whole day. A detailed mechanism is as followed:
10% trigger limit: If this limit is breached before 1 pm, trade is halted for 45 minutes. If the same is breached between 1 pm to 2.30 pm, trade is halted for 15 minutes. After 2.30 pm, there is no halt in trading.
15% trigger limit: If this limit is breached before 1 pm, trade is halted for 1 hour 45 minutes. If the same is breached between 1 pm to 2.30 pm, trade is halted for 45 minutes. After 2.30 pm, trade is halted for the remainder of the day.
20% trigger limit: If this limit is breached any time during trading hours, trading is halted for the remainder of the day.