John Meissner wrote: >Hi Ron, > I'm just wondering if you are using a "dump" circuit to drain off >the back voltage when slowing the motors rapidly? I'll be using a >75VDC supply and after what you say about the 118VDC breakup point, >would a dump be absolutely necessary? > > Assuming a mid-sized machine and typical motors, and the recommended size of filter capacitors in the power supply, it probably is not necessary. I did some measurements, and rapid stops even on multiple axes at the same time only caused the power supply voltage to rise about 2 volts. A very heavy machine with minimal friction, very low resistance motors, and small filter caps on the power supply could make the rise greater. You can always set it up, and put a voltmeter on the supply. Accelerate and slow down first one axis, then two at a time, then three. If the voltage surges higher than you feel safe, then get the dump circuit.
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