F06500 — Infeed: Line synchronization not possible

F06500 is raised when the infeed cannot synchronize to the line supply within the monitoring time. The infeed had re-synchronized to the line supply because synchronization was interrupted — through an incorrect line frequency or through excessively high line voltage distortion — and after 20 attempts both the synchronization and the switching-on operation were interrupted. The manual also notes that for chassis power units the availability of correct voltage measured values from the Voltage Sensing Module (VSM) is imperative for line synchronization.

• The line synchronization could not be completed within the monitoring time.
• The infeed had re-synchronized to the line supply after synchronization was interrupted — because of an incorrect line frequency or excessively high line voltage distortion.
• Synchronization and the switching-on operation were interrupted after 20 attempts.
• On ALM chassis units in particular, the bypass contactor or the circuit breaker does not close.

1. Check the parameterized line frequency (p0211) and change it if required.
2. Check the setting of the threshold values p0284 (Line supply frequency exceeded alarm threshold) and p0285 (Line supply frequency undershot alarm threshold).
3. Check the line supply.
4. Check the connecting terminals.
5. If a bypass contactor is being used, check it and its associated control.
6. Check the state of the circuit breaker and its associated control.
7. For significant line voltage distortion, the tolerance threshold p3457[2] can be adapted — but only after assessment by experts.
8. When a Voltage Sensing Module (VSM) is used:
   • check the line supply connection at the terminals (X521, X522);
   • check the VSM activation (p0145, p3400);
   • check the line supply quality.

• p0211 — the parameterized line frequency; check the setting and change it if it does not match the actual line supply.
• p0284 — Line supply frequency exceeded alarm threshold; check its setting for this fault.
• p0285 — Line supply frequency undershot alarm threshold; check its setting for this fault.
• p3457 — Infeed PLL supplementary settings; for significant line voltage distortion its tolerance threshold p3457[2] can be adapted, but only after assessment by experts.
• p0145 — check it together with p3400 to confirm that the VSM is activated.
• p3400 — infeed configuration word; check it together with p0145 to confirm that the VSM is activated.

Remove the cause before acknowledging; the acknowledgment is expected immediately. Because the response switches the infeed off without a controlled ramp-down, the infeed does not accept a new switching-on command until the fault has been acknowledged — and in configurations that require it, only after a POWER ON.