Technical FAQs

# What time should I enter to make the drive ramp to 25 hz in 120 seconds?

Issue:
Acceleration time clairification

Product Line:
Altivar drives

Environment:
All models and serial numbers

Cause:
None

Resolution:
The ACCELERATION parameter (ACC) is the total time the drive ramps from 0 to the standard motor frequency (50 or 60 hertz) regardless of the low speed setting.  If the standard motor frequency is 60 hertz and the desired ramp time to reach 25 hertz is 2 minutes (120 seconds) the the setting for ACC should be 288 seconds.

The calculation for achieving this is as follows: time = frequency rate / running frequency
1.  Calculate the "frequency rate" by dividing the "running frequency" (25 hz) by the "time to frequency" (120 seconds).
(25/120 = .20833) the frequency will change at a rate of .2083 hertz per second.
2. Determine the total ACC time by multiplying the standard frequency (50 or 60 hz) by the inversion of the frequency rate.
60 * (1/.2038)
60 * 4.8 = 288
At this rate it will take 288 seconds to reach 60 hz and 120 seconds to reach 25 hz.