Magnetic circuit breakers make use of field strength of magnetic coils to trip a latch that will then open up contacts of circuit breaker. This method is used for high current faults, like in a short circuit. This method is designed to trip instantly.

A thermal-magnetic circuit breaker incorporates both a thermal strip and a magnetic coil. This type of circuit breaker is able to protect against momentary overloads as well as high or short circuit current faults.

What happens if circuit breaker is placed in a high temperature environment? The thermal bimetallic strip bends on high temperature. In this case, current is not causing high temperature in bimetallic strip, but ambient air is! The current may still be below safe operating rated value for motor.

In this case, a compensating bimetallic strip may be incorporated into circuit breaker to eliminate this type of error. These circuit breakers are often used in hot areas like furnace, oven, and boiler rooms.

Circuit breakers can be reset very quickly, once they have tripped. Can your break or vacation be reset very quickly too? Don't reset. Take a long break!

Until next time...

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There is another important difference too. Hollywood HD is uncompressed, whereas video shot by cameras like this Sony HD camcorder is compressed as MPEG-2. This compression inevitably lowers quality of video stored on camera’s DV tape. However, it’s necessary because HDR-FX1 connects to a computer using a FireWire cable and FireWire, whether it is 400 or 800 variety, doesn’t have bandwidth to transfer uncompressed HD footage. Even if it did, sheer size of files would make it impractical because of large amoount of hard disk space needed to store it and processing power needed to edit it.

Another fly in th HD ointment is that, currently, very few applications are able to edit footage from this Sony HD camcorder. However, that looks set to change,as Apple has already announced that next version of its Final Cut Express and iMovie applications, due at end of January, will be able to edit HD.

HD video will eventually become a common consumer format, when prices come down and editing software is able to work with it. However, until a compression format is found that can squeeze data contained in HD without noticeably reducing quality, there will be little benefit over current DV format camcorders.