Link copied. Please paste this link to share this article on your social media post.
Posted: 2023-12-2608:27 PM
I'm not particularly familiar with the Altivar drives. But this is likely something common amongst all drives.
There are two things which can heat up based on motor load (current).
The Drive (whether VSD / Soft Starter / DOL Contactor)
The motor size and cooling dictate the first, and the drive 'frame size' and cooling dictate the second.
You can hook a 2MW motor up to a 1kW drive. But you shouldn't expect to get 2MW of mechanical work performed from it. It will almost certainly trip on a Drive Overload long before it reaches the thermal model of the Motor Overload.
The Motor thermal model can depend on a number of things, like the rotational speed, the bus voltage, the back EMF, the field magnetisation, and the armature current.
The Drive thermals will generally only be due to the phase current (of which a component will be 'armature current', and a component will be field current).
I would say that OL1 = Drive Overload (purely current based, which will be either an inherent current limit to protect the drive, or a customisable current which can be less than or equal to the drive protection current), whilst OL2 = Motor Overload (based on the thermal model of the motor that the drive is constantly updating).
Lead Control Systems Engineer for Alliance Automation (VIC). All opinions are my own and do not represent the opinions or policies of my employer, or of my cat..