Danfoss VLT AutomationDrive FC 302 troubleshooting
The VLT AutomationDrive FC 302 is Danfoss’s general automation AC drive (the FC 301 is the lower-spec variant covered by the same manuals). Warnings and alarms share one numbered list: a warning shows its number on the LCP while the drive keeps running, an alarm trips the drive and flashes its number, shown as for example "Earth Fault [A14]". Start any diagnosis by reading the alarm log, then decide from what the machine was doing which cause to check first.
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How it reports faults
- Warning: yellow Warn. light on and the warning number shown on the LCP; the drive keeps running. Alarm: red Alarm light flashes with the alarm text and number, e.g. "Earth Fault [A14]". Trip lock: both lights on.
- The [Alarm Log] key shows current warnings, the last 10 alarms and the maintenance log.
- Parameter 15-30 Fault Log: Error Code (array of 10) holds the alarm codes; 15-31 Fault Log: Value adds detail (mostly for alarm 38, internal fault); 15-32 Fault Log: Time is seconds since the drive was powered up.
- Many alarms can be set to warn, trip or do nothing through their own parameter (e.g. 1-90 for motor thermal alarms, 14-12 for mains imbalance), so read the setting before assuming the alarm is fixed behaviour.
- Reset with [Reset] on the LCP, a digital reset input, a serial-communication reset or auto reset, once the cause is removed.
- Software version is in parameter 15-43; use the Programming Guide edition that matches it.
Fault codes
| Code | Name |
|---|---|
| A13 | Overcurrent |
| A14 | Earth (Ground) Fault |
| A7 | DC Overvoltage |
| A8 | DC Undervoltage |
| A4 | Mains Phase Loss |
| A9 | Inverter Overload |
| A10 | Motor ETR Overtemperature |
| A29 | Heat Sink Temp |
| A2 | Live Zero Error |
| A3 | No Motor |
| A11 | Motor Thermistor Overtemperature |
| A12 | Torque Limit |
| A16 | Short Circuit |
| A17 | Control Word Timeout |
| A22 | Hoist Mechanical Brake |
| A26 | Brake Resistor Power Limit |
| A27 | Brake Chopper Fault |
| A28 | Brake Check Failed |
| A30 | Motor Phase U Missing |
| A31 | Motor Phase V Missing |
| A32 | Motor Phase W Missing |
| A33 | Inrush Fault |
| A34 | Fieldbus Communication Fault |
| A36 | Mains Failure |
| A38 | Internal Fault |
| A45 | Earth Fault 2 |
| A46 | Power Card Supply |
| A65 | Control Card Overtemperature |
| A68 | Safe Stop Activated |
| A69 | Power Card Temperature |
| A99 | Locked Rotor |
Evidence to collect
- Photo of the LCP showing the alarm text and number
- Alarm log entries (15-30 to 15-32) or an MCT 10 export
- Parameter 15-43 software version and 15-45 type code
- Motor rating plate and parameters 1-20 to 1-25
- What the machine was doing at the trip (start, ramp, steady run, stop)
Work on fuel trains, burners, pressure vessels and electrical equipment must be done by qualified personnel following the manufacturer’s documentation and local codes. Never bypass a safety device or interlock.