Re: [CAD_CAM_EDM_DRO] Re: How to blow a Gecko 320

Vince Negrete wrote:

>>Mariss Freimanis wrote:
>>
>>
>>
>>>Eric,
>>>
>>>Shutting of the AC is the best way. Switching the DC to the drives is
>>>the worst way.
>>>
>>>
>>>
>>>
>>>
>>How about throwing a fairly heavy drain resistor across the capacitor
>>bank to drain it more quickly, and brake the motors if they are still
>>moving? Using the NC contacts of a relay held in by the AC supply would
>>do that.
>>
>>
>>
>
>ha! Great idea Jon! I'm glad you thought of it. Thanks... :) <kidding..>
>
>Think Mariss was talking against using the Gecko to do DC shutdowns.
>Also, unless there is a negative Polarity I dont see how it can "Brake"
>any motors. Motors will just Coast in that situation.
>
>

No, the frewheeling diodes in the Gecko or other full-bridge driver will
direct
current from the motor back to the power supply. Once the cap bank in the
power supply has dropped below the back EMF produced by the motor, current
will flow from the motor, through the drive (even if shut off) to the
braking
resistor. Then, the motor will be braked to a stop. Just short out a
permanent
magnet brush motor and turn it by hand, if you think it will "coast".

Jon