Protection is a vast field and it’s designing, and implementation is a subject of involved Technicality and Engineering Experience to larger extent. For Switchgears, Protective Relays are designed to provide protection for electrical equipment and hence Engineering toward Designing of Protection Scheme and Protection Relaying must be done keeping all the aspects in mind.
During all these years in Engineering Services, we have mastered the art of Design and Selection of Protection Scheme. We have also helped many of our valued customers to Rectify the issues related to wrongly Designed and Implemented Protection Schemes and Philosophies.
Presenting you one of such case which we, System Protection have Identified and Rectified for wrong Design of Protection Scheme which in turn reduces Selectivity and increases down time or remain Inoperative in case of some genuine fault conditions.
In one of the Process Plant where switchboard was designed by some consultant who showed ignorance owing to lesser experience and knowledge in Design & Engineering of Protection Schemes. This has costs frequent failure of 6.6 kV HT Motors without any warnings and abnormality reflected.
Till date we, System Protection were contacted and called upon to identify and rectify the root cause, 3 Motors have been burnt due to Overheating / Overloading in just 9 -10 months.
Usually, we never suspect the Engineering of Protection Schemes, hence started analyzing the data viz. Motor Ratings, CT Sizing, Transformer Ratings, Relay Settings, Load patterns, connected loads etc. Examining further when no check points left, we finally checked the Protection Scheme and SLD that lead us to an instant conclusion that it was wrong Protection Scheme for Motors causing frequent failure and loss of revenue with significant repairing cost and down time.