Open transition switching causes very high current transients. These transients can be in the order of 10 - 20 times the rated current of the motor. Torque is proportional to current squared, so the torque transients are even worse. These transients are commonly the cuase of mechanical damage to the motor and driven load. - doesn't break every time, but the life is shortened. If you eliminate the transients, the gear will last longer.
You need to have an OFF time long enough for the rotor field to decay significantly. This requires a delay in the order of a second or two. It is not important that the motor slows to zero speed, just that the rotor field has almost disappeared.
Best regards,
Mark Empson
http://www.LMPhotonics.com |
http://www.LMPForum.com [This message has been edited by marke (edited 09-10-2005).]
