Abstract:
In most tropical countries like Sri Lanka, lightning activity is high and can cause severe damage to equipment within buildings. Thus lightning surges should be prevented from entering sensitive equipment by installing high quality surge protection devices. Traditionally, surge protection circuits use non-linear devices to clamp the overvoltage. However, typical non-linear devices have low relatively short duration energy absorption ratings and cause the life of the surge protection device to decrease.
As it is known that supercapacitors have large continuous energy storage capabilities, a supercapacitor based surge energy absorption technique has been developed by combining a multi-winding magnetic component with a typical non-linear device in a novel configuration. This research presents an overview of new supercapacitor technique and the basis for selecting the magnetic core required so that the supercapacitor sub-circuit works effectively.
Selection of the magnetic core is critical for the success of the technique, since the combination of the leakage and magnetizing components of the multi-winding magnetic core plays a dominant role. Experimental results generated using a lightning surge simulator with surge capability up to 6 kV/3 kA are used to validate the results. Overall performance of this technique with optimized magnetics is compared with a typical commercially available surge protector, which is practically used to safeguard electronic systems against transient over-voltage related power quality issues.
This technique utilizes a multi-winding transformer, common surge protector devices such as metal oxide varistors combined with a supercapacitor sub-circuit to absorb part of the surge energy usually expected to dissipate within the metal oxide varistor and improve the life of the surge protective device. Also the output clamping voltage is controlled to a lower value to give better protection for the equipment.
Test results clearly indicate, the supercapacitor assisted surge protective device has a much higher energy absorption capacity than tested commercial products and can be used in commercial surge protectors with better performance than traditional surge protectors with higher component counts.
