Fault trip indicator and maintenance method for a circuit breaker

A fault trip indicator for use with a circuit breaker connected to protect an electrical line, the circuit breaker having a protective circuit for opening the circuit breaker during a heavy load condition on the electrical line, the fault trip indicator comprising:

• a current transformer coupled to the electrical line to produce a current signal which varies as a function of a current level flowing through the electrical line;
• a battery-powered threshold detector coupled to the current transformer to produce a load signal when the threshold detector detects that the current signal exceeds a threshold value;
• and
• a monitoring circuit coupled to the protective circuit and the threshold detector for providing an indication of the occurrence of the protective circuit opening the circuit breaker while the threshold detector is producing the load signal.

A fault trip indicator for use with a circuit breaker connected to protect an electrical line, the circuit breaker having a protective circuit for opening the circuit breaker during a heavy load condition on the electrical line, the fault trip indicator comprising:

• a current transformer coupled to the electrical line to produce a current signal which varies as a function of a current level flowing through the electrical line;
• a threshold detector coupled to the current transformer to produce a binary load signal when the threshold detector detects that the current signal exceeds a threshold value;
• and
• a monitoring circuit coupled to the protective circuit and the threshold detector for providing an indication of the occurrence of the protective circuit opening the circuit breaker while the threshold detector is producing the binary load signal.

A fault trip indicator for use with a circuit breaker connected to protect an electrical line, the circuit breaker having a protective circuit for opening the circuit breaker during a heavy load condition on the electrical line, the fault trip indicator comprising:

• a current transformer coupled to the electrical line to produce a current signal which varies as a function of a current level flowing through the electrical line;
• a passive threshold detector coupled to the current transformer to produce a load signal when the threshold detector detects that the current signal exceeds a threshold value;
• and
• an indicator coupled to the protective circuit and the threshold detector to provide an indication of the occurrence of the protective circuit opening the circuit breaker while the threshold detector is producing the load signal.

A method of performing maintenance on a circuit breaker, the circuit breaker being connected to protect an electrical line and being of a type having a protective circuit for opening the circuit breaker during a heavy load condition on the electrical line, the method comprising:

• producing a current signal which varies as a function of a current level flowing through the electrical line;
• establishing a first threshold value;
• producing a binary load signal as a function of the current signal and the first threshold value;
• providing an indication of the occurrence of the protective circuit opening the circuit breaking while the binary load signal is being produced;
• establishing a second threshold value;
• and
• performing maintenance on the circuit breaker as a function of the indication and the second threshold value.

A method of performing maintenance on a circuit breaker, the circuit breaker being connected to protect an electrical line and being of a type having a protective circuit for opening the circuit breaker during a heavy load condition on the electrical line, the method comprising:

• producing a current signal which varies as a function of a current level flowing through the electrical line;
• establishing a first threshold value;
• using battery power to produce a load signal as a function of the current signal and the first threshold value;
• providing an indication of the occurrence of the protective circuit opening the circuit breaking while the load signal is being produced;
• establishing a second threshold value;
• and
• performing maintenance on the circuit breaker as a function of the indication and the second threshold value.