---------------------------------------------------------- Avionics-List Digest Archive --- Total Messages Posted Sun 12/19/04: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 10:34 AM - Pull type aircrat Circuit Breakers and other types.... (David Lloyd) 2. 06:05 PM - Re: Pull type aircrat Circuit Breakers and other types.... (Fred Fillinger) 3. 06:34 PM - Re: Pull type aircrat Circuit Breakers and other types.... (Joemotis@aol.com) ________________________________ Message 1 _____________________________________ Time: 10:34:54 AM PST US From: "David Lloyd" Subject: Avionics-List: Pull type aircrat Circuit Breakers and other types.... --> Avionics-List message posted by: "David Lloyd" Anyone familiar with the "insides" of the typical circuit breakers (CB) that we use on our aircraft? I am curious what the mechanism is that makes a CB go intermittent or bad, particularly the low amperage units. Also curious if "pulling" and resetting the breaker occasionally might be good for it, by possible cleaning or re-setting any contact points inside. I have never cut one apart and looked at the mechanism...especially the low current units. Let's hear from the gurus..... David ________________________________ Message 2 _____________________________________ Time: 06:05:57 PM PST US From: "Fred Fillinger" Subject: Re: Avionics-List: Pull type aircrat Circuit Breakers and other types.... --> Avionics-List message posted by: "Fred Fillinger" David Lloyd wrote: > Anyone familiar with the "insides" of the typical circuit breakers (CB) > I am curious what the mechanism is that makes a CB go intermittent > or bad, particularly the low amperage units. The # of cycles will be in the data sheet for pullable types. For example, the P & B W-23 is 10,000 cycles, 6,000 at 100% of rated load. Of course, not in their literature is anything about the "mechanism that makes a CB go intermittent or bad, particularly the low amperage units." Especially if you're referring to the kind you can't pull, is this documented somewhere? Reg, Fred F. ________________________________ Message 3 _____________________________________ Time: 06:34:18 PM PST US From: Joemotis@aol.com Subject: Re: Avionics-List: Pull type aircrat Circuit Breakers and other types.... --> Avionics-List message posted by: Joemotis@aol.com Most breakers lever, push pull etc are all very similar. That is, a spring loaded device that is tripped by a resistive element that when it heats up unlatches or pushes over the spring loaded trip device. Another style uses a clicker BI metallic spring that literally "pops" when it passes more than the rated current. All large breakers (480, 4160,6600,14.4K volt 3 phase) in 90++ buildings I do energy management on, with ranges from 5 amps to 5000 amps, are exercised yearly. Joe Motis 601 XL Do not archive