Methods and apparatus for an improved magnetic armature selective tripping device of a circuit breaker

A circuit breaker comprising:

• a housing enclosing the circuit breaker and a selectivity device, the selectivity device including:
• a modular assembly adapted to be coupled to a load conductor assembly of the circuit breaker, the modular assembly including:
• a tripping plunger including a cam surface adapted to interact with a breaker tripping mechanism, the cam surface having a shape selected to configure tripping characteristics of the selectivity device for the circuit breaker such that the shape to provide a cam profile that is tunable to change an amount of energy required from a magnetic structure to trip the circuit breaker;
• an armature coupled to the tripping plunger;
• a yoke adapted to generate a magnetic field in response to an electric current in the load conductor assembly and disposed to apply a magnetic force proportionate to the electric current on the armature;
• and
• a spring assembly adapted to counter-balance the magnetic force up to a predefined tripping current in the load conductor assembly, the spring assembly is configured to enable selection of springs to provide a spring rate profile that changes an amount of energy available to trip the circuit breaker.

A method of selectively tripping a circuit breaker, the method comprising:

• selecting a cam surface having a shape selected to configure tripping characteristics of a selectivity device for the circuit breaker, wherein the cam surface having the shape to provide a cam profile that is tunable to change an amount of energy required from a magnetic structure to trip the circuit breaker;
• installing the selectivity device with the selected cam surface on a load conductor assembly of the circuit breaker;
• and
• monitoring current flowing through the load conductor assembly so that the selectivity device reacts to a current flow at or over a predefined amount of current, wherein the selectivity device including a spring assembly that is configured to enable selection of springs to provide a spring rate profile that changes an amount of energy available to trip the circuit breaker,
• wherein installing the selectivity device includes installing the selectivity device including:
• a modular assembly adapted to be coupled to the load conductor assembly of the circuit breaker, the modular assembly including:
• a tripping plunger including the cam surface which is adapted to interact with a breaker tripping mechanism;
• an armature coupled to the tripping plunger;
• a yoke adapted to generate a magnetic field in response to an electric current in the load conductor assembly and disposed to apply a magnetic force proportionate to the electric current on the armature;
• and
• the spring assembly including two or more springs and adapted to counter-balance the magnetic force up to the predefined amount of current in the load conductor assembly.