F07901 — Drive: Motor overspeed

F07901 is raised when the actual motor speed leaves the permissible window. The drive does not use a single limit: the effective positive limit is the smaller of p1082 and the limit interconnected via CI at p1085, plus the hysteresis p2162; the effective negative limit is the larger of -p1082 and the limit interconnected via CI at p1088, minus the same hysteresis. Both effective limits can be read live in r1084 and r1087. On G120XA the drive additionally raises this fault when it has identified that the motor has been stalled longer than the time set in p2178; that case is recognisable from the fault value in r0949.

• The speed exceeded the effective positive limit: the smaller of p1082 and the CI-interconnected p1085, plus the hysteresis p2162.
• The speed fell below the effective negative limit: the larger of -p1082 and the CI-interconnected p1088, minus the hysteresis p2162.
• On G120XA, additionally: the drive identified that the motor has been stalled for a time longer than the delay time p2178; this path is signalled with fault value 2 in r0949.

1. Establish the direction of rotation. For positive rotation, check the effective limit in r1084 and, if required, correct p1082, the CI-interconnected p1085 and the hysteresis p2162.
2. For negative rotation, check the effective limit in r1087 and, if required, correct p1082, the CI-interconnected p1088 and p2162.
3. Switch on precontrol of the speed limiting controller (p1401.7 = 1).
4. If the trips are marginal, enlarge the hysteresis for the overspeed signal in p2162. How far this can go depends on the maximum motor speed p0322 and on the setpoint channel's maximum speed p1082.
5. If the fault value in r0949 is 2, the trip came from stall detection (threshold p1745, or the flux values r0084 and r0083) rather than from a genuine overspeed; the further steps for that path are listed with F07902.

• Most manuals print no message value for this fault. Where one is given, it is stored in r0949 and is to be interpreted as a decimal number.
• 1: reserved.
• 2: stall detection, either via the motor model stall threshold p1745 or via the flux values r0084 and r0083.

• p1082 — maximum speed of the setpoint channel; the base value of both overspeed limits, corrected here.
• p1085 — speed limit for positive rotation, interconnected via CI; it caps the effective positive limit below p1082.
• p1088 — speed limit for negative rotation, interconnected via CI; it caps the effective negative limit.
• p2162 — hysteresis between actual speed and maximum speed; enlarge it against repeated trips, within the bounds set by p0322 and p1082.
• r1084 — effective positive speed limit; read here to see the positive limit actually active.
• r1087 — effective negative speed limit; read here to see the negative limit actually active.
• p0322 — maximum motor speed; together with p1082 it bounds how far p2162 may be raised.
• p1401 — flux control configuration; the setting that switches on precontrol of the speed limiting controller sits here.
• r0949 — fault value; read it as a decimal to tell a genuine overspeed from the stall-detection path.
• p2178 — motor stalled delay time; exceeding it can raise this fault on G120XA.
• p1745 — motor model stall threshold; one of the stall-detection criteria behind fault value 2.
• r0084 / r0083 — flux actual value and flux setpoint; the stall detection can also evaluate these two against each other.

The drive coasts the motor down (OFF2) and must be acknowledged before it will restart. Find and remove the cause first; after restarting, compare the actual speed with the effective limits in r1084 and r1087.