Eliminated from:
Inverter Drives 8400 StateLine, HighLine, and TopLine from firmware version 12.00.00.00
Behaviour of the new version?
The speed controller setpoint is loaded with the current speed at controller enable. A magnetisation of the ASM is only carried out if the actual speed value is lower than the rated slip speed.
By means of these two measures, the compensation currents during connection to a rotating motor are minimised.
Which products are affected?
Inverter Drives 8400 StateLine, HighLine, and TopLine with a firmware version lower than 12.00.00.00
What happens?
During connection to a rotating motor, partly a noticeable motor noise, a 'clicking noise', can be noticed. Compensation currents flow, which, in the worst case, result in an overcurrent error.
When does the problem occur
In the 'Servo control ASM' motor control mode (C006=2), when the inverter is enabled, while the motor is still rotating. The impact of the compensation processes is more distinct for high motor speeds and motors with a high power.
The behaviour is caused by two characteristics:
• After inverter enable, the speed setpoint for the motor control is only enabled if the motor magnetising current has reached the threshold value set in C918. The Lenze setting is C918=87%
This deceleration deteriorates the compensation behaviour.
• Instead of the actual speed value, the speed controller setpoint with the auto-DC-injection braking threshold is initialised.
Diagnostics options?
Check whether the connection behaviour can be continuously improved by reducing C918 to zero.
Short-term measures/recommendations?
Reduction of the start motor magnetising current in C918.
Evaluation:
The impacts of the behaviour are usually not so distinct that a monitoring function is activated. The behaviour can be optimised by parameter adaptation. If application to n_act ≠0 is not explicitly tested, the behaviour is not detected during commissioning yet.
