Design and Analysis of Pre-Insertion Resistor Mechanism

Abstract

In electrical system, circuit breaker is used to make or break current for different power system equipments like transformers, reactors, transmission lines, capacitor banks etc. in normal as well as abnormal (short circuits, over voltages and many more) conditions. These conditions create switching over voltages. This can be substantially damped by inserting pre-insertion resistor in circuit.

The existing electrically parallel pre-insertion resistor is to be converted in to an electrically series pre insertion resistor mechanism with mechanical and electrical feasibility. The mechanism is comprised of two electrical contacts and certain means for controlling the motion of the electrical contact. The motion of two electrical contacts should be controlled to insert the resistor for 10 ms as soon as the circuit breaker is closed and bypass the resistor while opening the circuit breaker.

Five different concepts are developed from scratch. Dynamic motion analysis is carried out in MSC ADAMS adjusting various control parameters. Stress analysis of critical components is carried out and subsequent shape modification is followed by final dynamic analysis which aligns with the requirement. A mathematical model for contact phenomenon has been developed and solved in SCI LAB and the results are compared with MSC ADAMS software results.