Add-on stabalization technique in Bus Bar protection

 Introduction: In earlier post we have discussed about Bus bar differential protection.

For Low impdance bus bar protections, different manuafacturer use different algorithm to avoid mal-operation of relay during CT saturation.

Add-on stabalization technique: One of the method is use of Add-on stabalization technique for detecting internal / external faults. Due to sharp reduction of current of one of the CT due to CT saturation, biasing current will reduce sharply, and relay may issue trip. 

With add-on stabilization, biasing current reduces at a slower rate. After half cycle current appears again in CT secondary circuit and biasing current will increase again as per actual. In this way, differential relay remain stable in case of CT saturation.