Implications of Direct and Indirect Heating of Bi-Metallic Strip in MCCBs – Challenges and Solutions


Sudhakar Sapuram
Suresh Srikantaiah
Amit Kumar Vishnoi
Siraparapu Satyanarayana


This describes about the main differences between direct and indirect heating of bi-metals for overload protection for MCCBs. It also explains about analysis of thermal behavior of bimetal strip during both steady-state and transient conditions. To validate the thermal model, experimental tests both in steady-state and transient conditions have been done. The time current characteristics curves for both types of MCCB are plotted for meeting relevant product standards and same is validated with actual tripping time. There is a good correlation between experimental and theoretical results. Direct heating of bi-metal element can help in reduction of electrical stresses and also increases the life span of the power cables. It also outlines the challenges overcome during development and solutions for implementation of direct and indirect heating of bi-metal strips for developing the MCCBs for fulfillment of IEC 60947-2 as well as REC specifications.


How to Cite
Sapuram, S., Srikantaiah, S., Vishnoi, A. K., & Satyanarayana, S. (2020). Implications of Direct and Indirect Heating of Bi-Metallic Strip in MCCBs – Challenges and Solutions. Power Research - A Journal of CPRI, 33–38.


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