Circuit breaker with magnetic shield

摘要

A pivoting lower contact arm arrangement and a circuit breaker including the arrangement. The pivoting lower contact arm arrangement includes a pivoting lower contact arm and a biasing arrangement. The biasing arrangement maintains the contact arm in an operating position with a first force, and biases the arm from a blown-open position toward the operating position with a second force. The first force is greater than the second force to provide increased separating speed when the pivoting lower contact arm blows apart from a pivoting upper contact arm of the circuit breaker and moves from its operating position. The biasing arrangement also variously provides magnetic shielding and coupling between the pivoting lower contact arm and other current carrying components of the circuit breaker. The magnetic shielding enhances the blow-apart forces between the pivoting upper contact arm and the pivoting lower contact arm.