Quote Originally Posted by crjohnson View Post
Yea I was thinking of measuring the 240V mains going into my machine and seeing what it draws. If it starts to draw too much then I'll stop whatever I am doing.

Would you recommend fitting an external brake resistor as an added safety/protection feature? Common sense says "upgrade the supply capacity", which will happen at some point. But I'm always interested in the other things here and there which can be good insurance against larger dissasters

If so could you recommend any particular resistors? Cheers
The Resistor is sized for the VFD Drive being used, VFD Drive suppliers will have a listing of what will suit the Drive you have, make sure the VFD Drive can use this feature not all are created equal.

It's only needed if you can't stop the spindle fast enough, for your needs, most can do a 3 to 4second stop without having Breaking Resistor, a Breaking Resistor is nothing to do with safety, it only allows you to stop the motor faster, the resistor dissipates regenerated power to keep the bus voltage from exceeding the rated limit of the drive.

A normal VFD Drive will fault if you try and stop the motor too quickly, that is why they have a Parameter for this (Deceleration)