A07440 — EPOS: Jerk time is limited

In the EPOS function the drive calculates a jerk time from the acceleration, deceleration and jerk settings as Tr = max(p2572, p2573) / p2574. When this quotient comes out excessively high, the drive limits the jerk time internally to 1000 ms and signals this with alarm A07440. The alarm only tells you that the internal limit has taken effect; the drive itself takes no action. According to the manual's note, The alarm is also output if jerk limiting is not active, so its appearance does not tell you whether jerk limiting is switched on.

• The calculated jerk time results in an excessively high value — the drive computes it as the larger of p2572 and p2573 divided by p2574 — so the jerk time is limited internally to 1000 ms.

1. Increase the jerk limiting in p2574 so that the calculated jerk time no longer exceeds the internal limit.
2. Alternatively reduce the maximum acceleration (p2572) or the maximum deceleration (p2573); the drive calculates the jerk time from the larger of the two, so lowering either one lowers the calculated value.

• p2572 — EPOS maximum acceleration / a_max: together with p2573 it forms the numerator of the jerk time calculation; reduce it to bring the calculated jerk time down.
• p2573 — EPOS maximum deceleration / -a_max: the second value in the numerator of the jerk time calculation; reduce it if the deceleration is the larger of the two.
• p2574 — EPOS jerk limiting / Jerk lim: forms the denominator of the jerk time calculation; increase it so that the calculated jerk time no longer has to be limited to 1000 ms.

No acknowledgement is required for this alarm, and it does not cause the drive to trip or to change its operating state. Once p2574, p2572 or p2573 have been adjusted so that the calculated jerk time is no longer excessively high, there is nothing to acknowledge or reset at the drive.