RE: T/S Inertia

Page 9 of 9  

I have dealt with many three phase and single phase dynamic braking circuits, mostly in the 1-5 hp range and the number of phases on the motor makes no difference, for braking ability.
The three phase braking circuits are more costly due to more contacts needed to switch the load to the brake circuits. A simple SPDT switch will do for a single phase saw.
The units I dealt with in 2000 ampere tapchangers typically used DC injection (some were friction and some regenerative) and were set to time out and allow the mechanism to coast onto a "top dead centre" position ready for the next cycle. This could be made to stop "on the spot" if adjusted this way but gave drift back to the brake initiating cam problems, at times so the coast in was necessary. This would not be desirable to stop a machine for a human usage.
Nah, there's nothing special about a three-phase motor that allows dynamic braking.

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That is what got me about 10 years ago and it wasn't a PM66. If was an old Craftsman contractor's saw that I used to own. Shut the switch of and started to walk away with a handful of small spaces I had just cut off. I looked over my shoulder and noticed one on the table next to be blade. In a brain-dead moment I over-reached the blade and got nicked, to the bone, on a fingertip. Even the clunky old Craftsman was still spinning down.
Stupid but it sure taught a lesson.
RonB
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WOW! That is an exceptionally long time. I wonder if it is because of the type belt that is used, not the typical v-belt rather the less resistant serpentine belts.

That may be more to do with lighting. I recall 40 years ago my shop teacher warning to be careful around the blade during spin down as it went and out of phase with the floresent lighting. Basically working like an automotive timing light. It did indeed appear to be paused a few times when shud town. As it would slow to near in phase timing the blade would appear to go backwards, stop, spin forward, etc. If the blade takes an exceptionally long time to come to a stop the "in phase" periods with the lighting would last longer.
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