>> On Tuesday 12 February 2013 22:36:22 Przemek Klosowski did opine: >> >>> I thought this is a no-no---opening of the circuit causes the servo >>> driver stage to abruptly change from high-current to zero current >>> flow, bound to cause transients in every inductance in the system. >>> (I think I got the attribution right, above.)
Another way to do this is to open the DC supply to the servo drive and cut in a braking resistor. If it is a control loop fault, the usual freewheel/protection diodes in the servo amp's bridges will conduct energy from the motor to the braking resistor, resulting in a well-controlled stop. If transistors have failed to short in the servo amp, then the braking may be more abrupt. But, in all cases, the motors should stop, and this method of braking should not cause any further damage to drives, motors, etc. than might have been caused by the original fault. Also, you can use one set of relays for all your servo amps. (I actually make a solid state device that does this, it has the main pass transistor and a transistor to switch the braking resistor on.) Jon ------------------------------------------------------------------------------ Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
