Magnetic Chuck Power Supply For the Blanchard 42" No. 18

[laatsch55]

Ok....Through the chuck??

 

[laatsch55]

Heres some paper Joe.. Pages 33, 34, 35, 45

 

[laatsch55]

I believe you need a decaying AC magnetic field to do that Lee

After extensive reading today, reverse polarity DC demagging is acceptable in surface grinding operations. The polarities and current are lowered in a series of activations. So, if charging and discharging the mag field in a magnetic chuck happens over a minute or two, am I still ok with no flyback diode involved?

 

[laatsch55]

And, is there a better way to switch DC other than an electromechanical relay, even though the switched current is only 2.97 amps?

 

[Hexis22]

And, is there a better way to switch DC other than an electromechanical relay, even though the switched current is only 2.97 amps?

A big ass H-Bridge motor driver

 

[wattsabundant]

There are very few, if any contactors/relays rated for anything close to 100VDC. 480 VAC no problem. DC big problem. Current never goes to zero, contacts weld. With AC, current stops (arcing stops) every half cycle. I welded dozens of ice cube relays while developing relay boards.

IGBT's can handle the voltage, but they don't like fault currents. No fuse is fast enough to protect an IGBT against a fault. SCR's and diodes are fault tolerant.