The ACS250 is Now the ACS255
In January 2017, the ACS250 drive was replaced by the new ACS255 micro drive. The ACS250 was a popular VFD, and the ACS255 will be even better with new control board components, enhanced capabilities, and higher performance.
What Stayed the Same?
For existing ACS250 users, almost nothing changed. You basically change the ACS250 to an ACS255 when ordering. The drives still look the same, mount the same, cost the same, and have the same connection terminals in the same locations.
All improvements in the ACS255 are internal to the drive. In fact, unless you go looking for the Advanced parameter menu, the only difference you'll notice is the new ACS255 part number.
Meet the New ACS255 Micro Drive
In the 115-480V drives, ABB added an Advanced parameter menu with sensorless vector control for both AC induction and permanent magnet synchronous motors, motor parameter autotune, operating mode selection for pump/fan/general use, and more.
Enhanced ground fault detection using current shunts protects against phase to earth faults at start-up. And the temperature sensor on the control board indicates when the ambient temperature is too high in the upper section of the drive and also indicates the switching frequency is too high without applying a de-rating factor.
The 600V drives already had sensorless vector control for AC induction motors, and it now supports permanent magnet motors.