Originally Posted by
Alan Schaffter
I forgot, some of those switches have a fixed or adjustable delay-on-off.
Cycling the vac motor probably won't be an issue, but I would read the specs on the auto-switch carefully. It probably has a cycle limit to keep the relay (if it has one) from overheating or prevent premature wear on the contacts.
Two other related issues to think about. First, check to see what effect the auto-switch has on the blade break- it may not work. You can test this by starting the saw and while it is running pull the plug. Some brakes rely on power to the brake circuit, some use reverse EMF from the motor to generate the power for braking. Maybe someone else with a little more knowledge can weigh in on this issue.
The other issue is the auto-switch sensing circuit may not be able to handle braking reverse EMF.
I'll check the specs on the relay unit to see if it has a duty cycle. Regarding the blade brake, if it's done electrically, the most likely thing that's being done is that when you switch the saw off, the motor is electrically converted from a motor to a generator (easy with universal motors). The power generated by the "generator" is dumped into a resistor. This converts the kinetic energy of the rotation of the saw to electrical energy. The resistor is sized to limit the current but to absorb the energy quickly, thereby acting like a brake. So nothing goes back to the grid or the relay unit - it's all contained in the saw.
But I'll try your suggestion of pulling the plug at the same time as I switch it off to see if the brake doesn't activate.
Mike
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