The public sector Bharat Heavy Electricals Limited (BHEL) has indigenously developed a state-of-the-art device for installation in the country's highest rating transmission systems of 400 KV lines to protect the series capacitors of the system from sudden rises in voltage.With the development of this vital equipment, called 'spark-gap' the country will not have to resort to imports and will be able to set up 400 KV series compensation systems with 100 per cent indigenous equipment.