Eliminated from:
Inverter Drives 8400 StateLine, HighLine and TopLine from firmware version 12.00.00.00
Behaviour of the new version?
The function of the DC-injection braking can be optimised by setting parameters, so that the monitoring function does not respond anymore.
1. Increase the waiting time for dissipating the magnetic field in the ASM before applying the braking voltage:
C2865/1 MCTRL special setting
Bit 1 = FALSE and bit 2 = FALSE: 250 ms for devices up to 2.2 kW, 1000 ms otherwise (default and as before)
Bit 1 = TRUE and bit 2 = FALSE: 250 ms
Bit 1 = FALSE and bit 2 = TRUE: 1000 ms
Bit 1 = TRUE and bit 2 = TRUE: 2000 ms
2. Use of the current controller (C0075, C0076) to control the braking current
MCTRL special setting C2865/1 bit 3 = TRUE
Which products are affected?
Inverter Drives 8400 StateLine, HighLine and TopLine with a firmware version lower than 12.00.00.00
What is the response?
When DC-injection braking is activated, the OC13 monitoring function (exceeding the maximum device current for a fixed switching frequency) responds.
When does the problem occur?
In the case of modulation modes with a permanently set switching frequency (C0018 = 5...8 and 15...18)
When DC-injection braking via auto-DC-injection braking is activated, or LS_MotorInterface.bDCBrakeOn = TRUE, a DC braking voltage is applied after a waiting time for the dissipation of the magnetisation. The following basic conditions support the occurrence of the behaviour:
- Motor power/device power > 1
- Motor is still strongly magnetised
- Great load torques and/or moments of inertia
Diagnostics options?
With C0018 = 2 (variable switching frequency), the behaviour does not occur at identical load conditions.
Short-term measures/recommendations?
Set variable switching frequency, e. g. C0018 = 2, and/or reduce C0036 current setpoint for DC-braking.
Evaluation:
If the inverter is in the 'Error' status, the load is not decelerated in a controlled manner, as expected for DC-injection braking, but coasts down. The behaviour occurs sporadically and is not necessarily detected during commissioning. The probability of occurrence is very low. There is a simple workaround.
