Soft start kit

[dickm]

Using worktop jig this afternoon and unusually, didn't make any stupid errors, but did suddenly wonder about something. Using one of my MOF177s, at the end of each cut, allowed the router to un-plunge and turned it off, then moved to another cut. Should you let the motor stop fully before starting the next cut? Does "soft-starting" when the motor is still turning, however slowly, cause any problems to the electronics?

 

[dickm]

Nobody got any ideas???
Myfordman, where are you hiding?

 

[sunnybob]

I dont see a problem on a motor. I would not do it if the motor was geared or if the motor had any external load on it.

 

[dickm]

My concern was more the electronics bit than the mechanics, which in the 177 are pretty robust. Things like "back EMFs" and other mysteries.

 

[deema]

A properly designed soft starter should have no issues. They use a sensor to determine the speed of the rotar and set the parameters accordingly to drive the motor. In essence the voltage is reduced initially to prevent a massive initial startup current caused by the motor being stalled (not rotating) which is equivalent to a short circuit electrically.

Normally, electrical switching on a motor that is already rotating places far less stress and wear on all mechanical and electrical bits in the motor and drive electrics. The inrush / initial current is avoided and it’s this that stresses the connections.

If a motor stalks when switched on, due to say too much load being applied the current it sees increases dramatically and causes the coils of wire in the motor to act like a heater. The motor very quickly heats up and burns out often causing a fire.