F07756 — Drive: Filter natural frequency > Shannon frequency

F07756 is raised when one of the filter natural frequencies configured for the drive is greater than the Shannon frequency. The drive calculates the Shannon frequency as 0.5 / p0115[0], i.e. from the sampling time for supplementary functions. The fault value in r0949, interpreted as binary, tells you which of the current setpoint filters is the one involved.

• The numerator or denominator natural frequency of one of the current setpoint filters — manipulated variable filter 1, manipulated variable filter 2, the manipulated variable filter or the precontrol filter — is parameterized higher than the Shannon frequency calculated as 0.5 / p0115[0].

1. Read the fault value r0949 interpreted as binary and identify the affected filter from the set bit (bit 0: manipulated variable filter 1, bit 1: manipulated variable filter 2, bit 3: manipulated variable filter, bit 4: precontrol filter).
2. Reduce the numerator or denominator natural frequency of the current setpoint filter involved so it no longer exceeds the Shannon frequency 0.5 / p0115[0].
3. Alternatively, reduce the controller sampling time (p0115[0]); the Shannon frequency calculated as 0.5 / p0115[0] then rises above the filter natural frequency.
4. Or deactivate the filter involved — the activation parameters are p1800 for the manipulated variable filter and p1721 for the precontrol filter.

• The drive writes the fault value to r0949; interpret it in binary. The set bit names the filter whose natural frequency is too high:
• Bit 0: Manipulated variable filter 1 (p1658, p1660)
• Bit 1: Manipulated variable filter 2 (p1663, p1665)
• Bit 3: Manipulated variable filter (p1800, p1805)
• Bit 4: Precontrol filter (p1721, p1727)

• r0949 — fault value: read it interpreted as binary; the set bit tells you which filter is involved.
• p0115[0] — sampling time for supplementary functions: it defines the Shannon frequency, 0.5 / p0115[0]; reducing this controller sampling time is one of the three remedies.
• p1658 — manipulated variable filter 1 velocity controller denominator natural frequency: reduce it when bit 0 is set.
• p1660 — manipulated variable filter 1 velocity controller numerator natural frequency: reduce it when bit 0 is set.
• p1663 — manipulated variable filter 2 velocity controller denominator natural frequency: reduce it when bit 1 is set.
• p1665 — manipulated variable filter 2 velocity controller numerator natural frequency: reduce it when bit 1 is set.
• p1800 — manipulated variable filter activation: use it to deactivate the filter flagged by bit 3.
• p1805 — manipulated variable filter numerator damping: belongs, together with p1800, to the manipulated variable filter of bit 3.
• p1721 — precontrol filter activation: use it to deactivate the filter flagged by bit 4.
• p1727 — precontrol filter numerator damping: belongs, together with p1721, to the precontrol filter of bit 4.

As standard this fault triggers no shutoff of the drive; an automatic response (OFF1, OFF2 or OFF3) can, however, be configured. Acknowledge the fault immediately, and a POWER ON is required before the drive restarts with the corrected setting. So after retuning or deactivating the filter, or after reducing p0115[0], acknowledge F07756 and switch the power supply off and on.