F07312 — Bypass LSS:

F07312 is raised by the bypass function when the feedback signals of the Line Side Switch (LSS) are not plausible. After every switching operation the function waits for the positive feedback signal from the switch; if the feedback is missing, arrives later than the specified time, or contradicts the requested bypass state, the drive trips and coasts down. The message value carries the fault cause as a binary bit pattern in r0949, so you can read exactly which of the four monitored conditions tripped the drive.

• The Line Side Switch does not return a plausible feedback signal — the expected "Closed" or "Open" feedback is missing.
• The switch feedback signal is too slow: after switching, the function waits for the positive feedback signal and shuts down when the signal arrives after the specified time has elapsed.
• The Line Side Switch feedback signal is not consistent with the bypass state: when switching on or when switching the motor in (staging), the line side switch closed without the bypass having requested this.

1. Read the binary fault value in r0949 to see which condition tripped the drive (bit 1, 2, 3 or 6).
2. Check the transfer of the feedback signals — the sources of the bypass switch feedback signal are configured in p1269, and for bit 3 compare the actual feedback time with the monitoring time in p1274.
3. Check the switch itself.

The drive stores the fault cause in r0949 as a binary value ("Fault cause: %1 bin"). The bits have the following meaning:

• Bit 1: Switch "Closed" feedback signal missing.
• Bit 2: Switch "Open" feedback signal missing.
• Bit 3: Switch feedback signal too slow. After switching, the system waits for the positive feedback signal. If the feedback signal is received later than the specified time, then a fault trip (shutdown) is issued.
• Bit 6: Line Side Switch feedback signal not consistent with the bypass state — when switching-on or when switching-in (staging) the motor, the line side switch is closed without this having been requested from the bypass.

• r0949 — fault value: holds the fault cause of this trip as a binary bit pattern (bits 1, 2, 3 and 6, see the decoding above).
• p1260 — bypass configuration: the configuration of the bypass function whose Line Side Switch is monitored here.
• p1266 — BI: bypass control command: the command with which the bypass function is operated.
• p1267 — bypass changeover source configuration: sets the source that triggers the bypass changeover.
• p1269 — BI: bypass switch feedback signal: the signal source of the switch feedback that you check for this fault.
• p1274 — bypass switch monitoring time: the "specified time" within which the positive feedback signal must arrive after a switching operation (bit 3).

The drive coasts down (OFF2 reaction) and must be acknowledged before it will start again. The acknowledgment class is IMMEDIATELY, i.e. the fault can be acknowledged directly after the trip. Once acknowledged and the feedback problem corrected, the drive can be restarted.