I took your advice and downloaded the operator's manual for the Lenze AC Tech SM vector drive and have read through it a couple of times. I have a couple of concerns:
# 1- I have some worry about the admonition about starting the drive into a coasting motor. In our application it should not be a big problem but there's always a chance that the operator could give a "stop" command, change his/her mind and immediately give a "run" command while the motor was still coasting down.
If I understand the manual, if we set the controller to stop with DC braking, the motor will not restart until it has come to a stop. That is, a "run" command would be ignored until the motor had stopped. Is that a correct interpretation?
#2 - Second, for the motor parameters required for torque limiting in vector torque mode, the stator resistance and stator inductance could be measured directly but the manual seems to suggest that those parameters would also be calculated by the controller during set-up, depending on how P399 is set. Am I interpreting this correctly?
#1 The drive will not start if the DC brake is active; but keep in mind, if the drive is set up for coast with a DC brake, the moment the drive sees a stop command the DC brake will engage. So, the motor will have a DC voltage applied and will probably still be spinning, you can do that, but it’s not good for all applications.
#2 As far as the stator resistance and inductance go. Those values are actually measured by the drive during the calibration for vector mode. So typically after entering 306-306, set 399 to standard calibration and apply a start command.
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