Molded case circuit breaker with cooling and protection for the static tripping unit

A multi-pole circuit breaker comprising:

• a molded case forming a housing, said case being constructed and arranged to have a partition which divides the case into at least two compartments within said housing which are sealed from one another;
• multiple circuit breaker poles mounted within and enclosed by one of said compartments and having input and output portions extending through and external to said housing;
• means associated with each pole for interrupting current flow between the input and output portions of each pole and including a static tripping unit subassembly including a tripping relay coupled within and enclosed by said one compartment, said tripping relay being constructed and arranged to cause interruption of current flow through said poles in response to a tripping signal;
• a current transformer associated with each of said poles and coupled within and enclosed by said one compartment adjacent its associated pole to provide a current signal representing a value of current flowing through its associated pole;
• an electronic processing means coupled within and enclosed by the other of said compartments and responsive to said current signals for providing a tripping signal in response to short circuit and overload conditions at said poles;
• means for coupling said tripping signal from said processing means to said tripping relay for causing an interruption of current flow through said poles, said means for coupling said triping signal extending between said one and said other compartment and being sealed to prevent communication between said one and said other compartment;
• at least one ventilation hole extending through said housing and communicating with said other compartment providing an opening external of said casing such that air external to said casing may circulate to within said other compartment for cooling said electronic processing means;
• and
• said one compartment being filled with circuit-breaking gases and said partition sealing said one compartment from said other compartment being constructed and arranged such that said circuit-breaking gases are retained solely within said one compartment and said partition further being constructed and arranged to reduce heat flow from said one compartment to said other compartment.