Vacon Drive Fault Codes

F1 / 1: Overcurrent

What it means: The drive measured a current far above its rating in the motor cable (more than 4 x IH on NX and VACON 100, 4 x IN on VACON 20) and tripped to protect itself. NX subcodes S1 to S4 tell which protection tripped (hardware trip, current cutter, current limit controller, software). VACON 100 shows fault ID 1 (hardware) or 2 (software).^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Fault, drive stops

Likely causes

• Sudden heavy load increase or a jammed machine
• Short circuit in the motor cable or motor
• Motor type or size does not suit the drive
• Motor parameters not set correctly, or acceleration time too short

First checks, in this order

1. Check the load and make sure the machine turns freely.
2. With power off, check the motor and motor cable for shorts and loose connections.
3. Check the motor nameplate data in the drive, then run a motor identification run (Identification, ID 631).
4. Lengthen the acceleration time (NX: Acceleration time 1, ID 103, P2.1.3 in the Standard application; VACON 100: P3.4.1.2 and P3.4.2.2).
5. On a VACON 20, check that the motor size matches the drive.

F2 / 2: Overvoltage

What it means: The DC link voltage went above the drive's safety limit, most often because the motor fed energy back into the drive while slowing down. NX subcodes: S1 hardware trip, S2 overvoltage control supervision, S3 LCL capacitor ripple (active front end units). VACON 100 shows fault ID 10 (hardware) or 11 (software).^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Fault, drive stops

Likely causes

• Deceleration time too short for the load inertia
• Regenerative or overhauling load driving the motor
• High voltage spikes on the supply
• Start and stop sequence too fast
• Overvoltage controller switched off

First checks, in this order

1. Lengthen the deceleration time (NX: Deceleration time 1, ID 104, P2.1.4 in the Standard application; VACON 100: P3.4.1.3 and P3.4.2.3; VACON 20: Par. 4.3 or 4.6).
2. Switch on the overvoltage controller (NX: ID 607, P2.6.10 in the Standard application; VACON 100: P3.1.2.10 Overvoltage Control).
3. Measure the supply voltage and look for spikes.
4. If the machine brakes hard on a regular basis, fit the optional brake chopper and brake resistor.
5. NX active front end with subcode S3: measure the LCL filter capacitors and check them against their rating.

F3 / 3: Earth fault

What it means: The sum of the three motor phase currents is not zero, so current is leaking to earth in the motor, the motor cable or an output filter. VACON 100 shows fault ID 20 (hardware) or 21 (software). The VACON 20 checks for extra leakage current at start.^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Programmable: no action, alarm or fault

Likely causes

• Damaged motor cable insulation
• Motor winding insulation failure
• Faulty dU/dt or sine filter between drive and motor

First checks, in this order

1. With power off, disconnect the motor cable at the drive and test the insulation of the motor and cable to earth.
2. Check any dU/dt or sine filter on the drive output.
3. Look for moisture, damage or crushed sections along the cable run and in the motor terminal box.
4. Check the response setting: NX Earth fault protection (ID 703, P2.7.7 in the Standard application); VACON 100 P3.9.1.12 Earth Fault (adjustable only on MR7, MR8 and MR9); VACON 20 P13.3.

F9 / 9: Undervoltage

What it means: The DC link voltage dropped below the drive's limit. NX subcodes: S1 DC link too low during run, S2 no data from power unit, S3 undervoltage control supervision. On a VACON 100 (fault ID 80) this fault only becomes active while the drive is in Run.^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Fault (NX response programmable)

Likely causes

• Supply voltage too low or a short supply break
• Blown input fuse
• External charging switch not closed
• Internal fault in the drive

First checks, in this order

1. If the supply dipped or dropped briefly, reset the fault and restart.
2. Measure the supply voltage on all phases and check the input fuses.
3. Look for problems on the plant supply network.
4. If the supply is correct, suspect an internal fault and contact your Danfoss distributor.
5. Check the setting: NX Response to undervoltage fault (ID 727, P2.7.5 in the Standard application); VACON 100 P3.9.1.4 Undervoltage Fault decides only whether it is stored in the fault history; VACON 20 P13.2.

F14 / 14: AC drive overtemperature

What it means: The heat sink or power board of the drive is too hot. On NX the drive warns at 85 °C and trips at 90 °C heat sink temperature (72 °C and 77 °C on 525 to 690 V FR6); subcodes S1 to S4 cover unit, power board, liquid flow and ASIC or driver boards. VACON 100 fault IDs: 130 fault and 131 alarm (heat sink), 132 fault and 133 alarm (board), 134 power unit auxiliary temperature, 136 and 137 overvoltage protection circuit temperature, 138 output filter, 139 brake chopper. VACON 20 calls it Frequency converter over temperature.^{[1][2][3][4][6]}

Also on: IDs 134, 138 and 139 appear only in the VACON 100 FLOW guide checked

Drive response: Alarm first, then fault

Likely causes

• Blocked or weak cooling air flow, or a failed cooling fan
• Dust on the heat sink
• Ambient temperature too high
• Switching frequency too high for the ambient and motor load
• Liquid cooled NX (S3): low coolant flow or a leak
• VACON 100 ID 136 or 137: too much output capacitance or an earth fault in an IT (floating) network

First checks, in this order

1. Check that the cooling fan runs and that air flows freely through the drive.
2. Clean dust from the heat sink.
3. Measure the ambient temperature at the drive.
4. Lower the switching frequency (NX: ID 601; VACON 100: P3.1.2.3).
5. Liquid cooled NX: check coolant flow, temperature and the circuit for leaks.
6. VACON 100 ID 136 or 137: check the motor cables and the motor.

F51 / 51: External fault (NX, VACON 20) / Device external fault (VACON 100)

What it means: A digital input set up as an external fault input is active, so outside equipment (for example a thermal relay, pressure switch or safety interlock) is telling the drive to stop. VACON 100 shows fault ID 1051.^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Programmable: no action, alarm or fault

Likely causes

• Fault in the external device wired to the input
• Broken wire to an input set as open = external fault
• Input assigned to the external fault function by mistake

First checks, in this order

1. Find and clear the fault in the external device, then reset.
2. Check which input is used: VACON 100 P3.5.1.11 External Fault Close (ID 405) or P3.5.1.12 External Fault Open (ID 406); DI3 is the default.
3. Check the wiring and the input status in the monitoring menu.
4. Check the response: NX Response to external fault (ID 701, P2.7.3 in the Standard application); VACON 100 P3.9.1.2; VACON 20 P13.18.

30: Safe Torque Off, Safe Off, Safety configuration, Safety diagnostics

What it means: Code 30 is the safety group on a VACON 100; read the fault ID. ID 530 Safe Torque Off: an emergency stop or other STO input opened and the drive is in its safe state. IDs 290 and 291 Safe Off: STO signal A or B stops the drive from going to READY. IDs 500 to 507 Safety configuration: the STO option board or safety configuration switch is fitted or placed wrong. IDs 520 to 527 Safety diagnostics: the STO inputs disagree, the ATEX thermistor input has a fault, or the internal safety circuit has a problem.^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: ID 530 programmable with P3.9.1.14: no action, alarm, or fault with coast stop

Likely causes

• Emergency stop pressed or safety relay opened (ID 530)
• Only one STO channel opened, or a wiring fault on the safety switch (ID 520)
• More than one STO option board, or a board in the wrong slot (IDs 501, 502)
• Safety configuration switch fitted, missing or in the wrong position (IDs 500, 503 to 505)
• ATEX thermistor input open or short circuited (IDs 521, 522)

First checks, in this order

1. Read the fault ID in the fault history first.
2. ID 530: find why the safety circuit opened, close it only when it is safe, then reset.
3. ID 520: check the external safety switch and the cabling of both STO inputs.
4. IDs 290, 291: reset and restart; if it comes back, check the signals from the control board to the power unit and the D connector.
5. IDs 500 to 507: check the STO option board slot and the safety configuration switch against the safety manual.
6. Check P3.9.1.14 Response to Safe Torque Off (STO) Fault (ID 775).

F30: Safe disable

What it means: The Safe Disable (STO) inputs SD1 and SD2 on the OPTAF option board have opened, so the drive is held in a safe stop.^[1][2]

Likely causes

• Emergency stop pressed or safety relay opened
• Wiring fault to the OPTAF board

First checks, in this order

1. Find why the safety circuit opened and cancel Safe Disable only when it is safe.
2. Check the cabling to the OPTAF board.
3. If the two channels stay in different states for more than 5 s, the drive shows F8 subcode S30 instead: check the S1 switch and the OPTAF cabling.
4. If the start command is still on when the drive returns to READY, expect F26 Start-up prevented (subcode S2): remove the run request first.

32: Fan cooling

What it means: Cooling fan alarm on a VACON 100. Fault ID 311: the fan speed does not follow its speed reference closely, but the drive still runs; this only shows on MR7 and larger frames. Fault ID 312: the fan has reached its 50,000 hour lifetime.^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Alarm; the manual says the drive keeps operating (ID 311)

Likely causes

• Dirty, blocked or worn cooling fan (ID 311)
• Fan lifetime counter has reached 50,000 h (ID 312)

First checks, in this order

1. ID 311: reset, then clean or replace the fan.
2. ID 312: replace the fan and reset the fan lifetime counter (B5.6.1.7 Fan lifetime reset in the VACON 100 FLOW guide).
3. Note that in Optimized fan mode (P5.6.1.1 Fan Control Mode) the fan stops 5 minutes after the drive goes to Ready, which is normal.

F32: Fan cooling

What it means: The NX cooling fan does not start when the drive gives it the ON command.^[1][2]

Likely causes

• Failed or seized cooling fan
• Fan supply or connector problem
• Fan blocked by dirt or debris

First checks, in this order

1. Check that the fan turns freely and is clean.
2. Check the fan connector and supply.
3. Ask your Danfoss distributor for instructions or a replacement fan.

F8 / 8: System fault

What it means: Internal fault in the drive electronics or software. NX subcodes (shown in the fault time data, T.14) point to the area, for example S1 ASIC phase feedback, S8 no power to driver card, S9 to S11 power unit communication, S12 system bus board in slot D or E, S30 to S50 OPTAF STO board. VACON 100 fault IDs 600 to 670 cover control board to power unit communication, CPU overload, software mismatch, Ethernet and auxiliary output voltage; IDs 827 to 830 are license key messages. On a VACON 20, read the F08 subcode in the fault history.^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Fault, drive stops (VACON 100 IDs 828 and 830 are notifications only)

Likely causes

• One-off malfunction or electrical disturbance
• Defective control board or power board component
• Control unit and power unit software do not match (VACON 100 IDs 606, 607)
• CPU or resource overload (VACON 100 IDs 608, 649)
• Overload or short on the auxiliary voltage output (VACON 100 ID 670)
• OPTAF STO board problem (NX subcodes S30 to S50)

First checks, in this order

1. Note the subcode or fault ID from the fault history before resetting.
2. Reset the fault and restart. For VACON 100 ID 609, reset and power the drive down twice.
3. On a VACON 100, update the drive software to the latest version from Danfoss.
4. VACON 100 ID 670: check the load on the auxiliary voltage output.
5. NX subcode S12: check the system bus cables and connections.
6. If it comes back, contact your Danfoss distributor with the subcode or fault ID.

F10 / 10: Input line supervision (NX) / Input phase (VACON 100) / Input phase fault (VACON 20)

What it means: A supply phase is missing. NX subcode S1 is diode supply phase supervision; S2 and S3 are for active front end units (line sync failed after five tries, or microgrid frequency out of limits). VACON 100 fault ID 91 needs at least 10 to 20% load to detect it; IDs 92 and 94 are software supervision on large frames (MR9B to MR12).^{[1][2][3][4][6]}

Also on: IDs 92 and 94 appear only in the VACON 100 FLOW guide checked

Drive response: Programmable on NX; fault on VACON 100

Likely causes

• Blown supply fuse
• Loose or damaged supply cable
• Supply voltage fault
• Rectifier bridge or thyristor gate control fault (VACON 100 MR6 and up)
• Drive fed from a 1-phase supply with 3-phase supervision active

First checks, in this order

1. Measure all three supply phases at the drive input.
2. Check the fuses and the supply cable.
3. VACON 100 MR6 and larger: check the rectifier bridge and the thyristor gate control.
4. On a 1-phase supply, set VACON 100 P3.9.1.3 Input Phase Fault (ID 730) to 1-phase support.
5. NX response: Input phase supervision (ID 730, P2.7.4 in the Standard application). VACON 20: P13.28.
6. NX active front end (S2): check that the input contactor closes, the fuses and the LCL filter.

F11 / 11: Output phase supervision (NX, VACON 100) / Output phase fault (VACON 20)

What it means: The current measurement sees no current in one motor phase. VACON 100 shows fault ID 100.^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Programmable: no action, alarm or fault

Likely causes

• Broken conductor or loose terminal in the motor cable
• Open motor winding
• Output contactor or switch open on one pole
• Faulty dU/dt or sine filter

First checks, in this order

1. Check the motor cable connections at the drive and at the motor.
2. With power off, measure the motor winding resistance phase to phase.
3. Check any output contactor, safety switch or filter between drive and motor.
4. Check the response: NX Output phase supervision (ID 702, P2.7.6 in the Standard application); VACON 100 P3.9.1.5; VACON 20 P13.4.

F16 / 16: Motor overtemperature

What it means: The drive's motor thermal model calculates that the motor is overloaded and too hot. It is calculated from the output current, not measured by a sensor. VACON 100 shows fault ID 150.^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Programmable: no action, alarm or fault

Likely causes

• Motor load too high for too long
• Long running at low speed with a shaft-mounted cooling fan
• Wrong motor nominal current or thermal model settings

First checks, in this order

1. Reduce the motor load and check the machine for binding.
2. Check the motor nameplate data set in the drive.
3. Check the thermal model settings: NX Thermal protection of the motor (ID 704) and IDs 705 to 708 (P2.7.8 to P2.7.12 in the Standard application); VACON 100 P3.9.2.1 to P3.9.2.5; VACON 20 P13.7 to P13.10.

F15 / 15: Motor stalled (NX, VACON 20) / Motor stall (VACON 100)

What it means: The stall protection tripped: the motor drew high current at low output frequency for longer than the stall time, so the drive treats the motor as stalled. VACON 100 shows fault ID 140.^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Programmable: no action, alarm or fault

Likely causes

• Jammed or blocked driven machine
• Load too heavy for the motor
• Stall current, stall time or stall frequency limits set too tight

First checks, in this order

1. Check that the motor and machine turn freely.
2. Check the load.
3. Check the stall settings: NX IDs 709 to 712 (P2.7.13 to P2.7.16 in the Standard application); VACON 100 P3.9.3.1 to P3.9.3.4; VACON 20 P13.5 and P13.11 to P13.13.

F17 / 17: Motor underload

What it means: The underload protection tripped: the motor load stayed below the set underload curve for longer than the time limit, which often means the load has been lost. VACON 100 shows fault ID 160.^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Programmable: no action, alarm or fault

Likely causes

• Broken belt or coupling
• Dry running pump or closed valve
• Underload curve or time limit set too tight
• Faulty dU/dt or sine filter (VACON 100)

First checks, in this order

1. Check the driven machine for broken belts, couplings or a dry pump.
2. Check the underload settings: NX IDs 713 to 716 (P2.7.17 to P2.7.20 in the Standard application); VACON 100 P3.9.4.1 to P3.9.4.4; VACON 20 P13.6 and P13.14 to P13.16.
3. VACON 100: check any dU/dt or sine filter.

F50 / 50: Analogue input Iin < 4 mA (NX) / AI low fault (VACON 100) / Analog input select 20% to 100% (VACON 20)

What it means: A live zero analog signal (4 to 20 mA, or 2 to 10 V on VACON 20) has dropped below its minimum, so the drive assumes the signal is lost. The VACON 100 trips when an input falls below 50% of the minimum signal range (fault ID 1050).^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Programmable: no action, alarm, alarm with preset frequency, or fault

Likely causes

• Broken or loose signal cable
• Failed transmitter or signal source
• Signal range set to 4 to 20 mA while the source sends 0 to 20 mA or 0 to 10 V

First checks, in this order

1. Measure the signal at the drive terminals.
2. Check the current loop wiring and the transmitter supply.
3. Check the analog input signal range setting (VACON 100: AI1 Signal Range).
4. Check the response: NX Response to the 4 mA reference fault (ID 700, P2.7.1 in the Standard application); VACON 100 P3.9.8.1 and P3.9.8.2; VACON 20 P13.1.

F53 / 53: Fieldbus fault (NX, VACON 20) / Fieldbus communication fault (VACON 100)

What it means: The data connection between the fieldbus master (for example a PLC) and the drive's fieldbus board is broken. VACON 100 shows fault ID 1053; the VACON 100 FLOW guide adds ID 1054 Redundant switchover and ID 1055 Redundant timeout.^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Programmable: no action, alarm or fault

Likely causes

• Fieldbus cable, connector or termination fault
• PLC or master stopped or not communicating
• Wrong fieldbus settings in the drive

First checks, in this order

1. Check the fieldbus cable, connectors and termination.
2. Check that the master is running and talking to this drive.
3. Check the fieldbus settings in the drive.
4. Check the response: NX Response to fieldbus fault (ID 733, P2.7.22 in the Standard application); VACON 100 P3.9.1.6; VACON 20 P13.19.

F7 / 7: Saturation trip (NX) / Saturation (VACON 100)

What it means: The drive detected IGBT desaturation, which usually means a hard short circuit or a failed power component. This fault cannot be reset from the control panel. VACON 100 shows fault ID 60.^[1][2][3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Fault, cannot be reset from the panel

Likely causes

• Defective IGBT in the power stage
• Short circuit or overload in the brake resistor
• Short circuit in the motor or motor cable (when shown together with fault 1 on NX)

First checks, in this order

1. Switch off the power. Do not restart the drive or power it up again before it is checked.
2. Contact Danfoss or your distributor for instructions.
3. With power off, if fault 1 Overcurrent appeared at the same time, check the motor cable and motor.
4. With power off, check the brake resistor and its wiring for a short.

F5 / 5: Charging switch

What it means: The DC link charging switch is not in the state the drive expects. On NX it is open when the start command is given; on VACON 100 (fault ID 40) it is closed but the feedback says open.^[1][2][3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Operation malfunction
• Defective component
• Feedback signal or cable problem between control board and power board (VACON 100)

First checks, in this order

1. Reset the fault and start the drive again.
2. VACON 100: check the feedback signal and the cable between the control board and the power board.
3. If it comes back, contact your Danfoss distributor.

F13 / 13: AC drive undertemperature (NX, VACON 100) / Frequency converter under temperature (VACON 20)

What it means: The heat sink or power board is too cold. NX and VACON 20 trip when the heat sink is below -10 °C. VACON 100 shows fault ID 120.^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Cold installation site, unheated room or outdoor cabinet

First checks, in this order

1. Measure the ambient temperature at the drive.
2. Add a heater near the drive (NX advice) or move the drive to a warmer place (VACON 100 advice).

F41 / 41: IGBT temperature (NX, VACON 100) / IGBT Overtemperature (VACON 20)

What it means: The calculated IGBT temperature in the inverter bridge is too high, usually from overload. NX subcodes: S1 calculated temperature, S3 long term protection, S4 peak current, S5 and S6 brake chopper unit current, S2 active front end current limit during a grid fault. VACON 100 shows fault ID 400. The VACON 20 raises an alarm when the IGBT passes 110 °C.^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Motor load too high for the drive
• High ambient temperature or poor cooling
• Switching frequency too high
• Motor data wrong or identification not done

First checks, in this order

1. Check the load and that the drive size suits the motor.
2. Check cooling air flow, the cooling fan, heat sink dust and ambient temperature.
3. Lower the switching frequency (NX: ID 601; VACON 100: P3.1.2.3).
4. Run a motor identification run.
5. NX subcode S6: check the brake resistor resistance.

F31: IGBT temperature (hardware)

What it means: The hardware IGBT overtemperature protection of the NX inverter bridge detected too high a short-term overload current.^[1][2]

Likely causes

• Load peaks too high for the drive
• Motor too large for the drive
• Motor data wrong or identification not done

First checks, in this order

1. Check the load.
2. Check the motor size against the drive rating.
3. Run a motor identification run.

F43: Encoder fault

What it means: The NX found a problem in the encoder signals or encoder setup. The subcode tells which: S1 channel A missing, S2 channel B missing, S3 both channels missing, S4 encoder reversed, S5 encoder board missing, S6 serial communication fault, S7 channel A and B mismatch, S8 resolver and motor pole pairs do not match, S9 start angle missing, S10 sin/cos feedback missing, S11 angle drifting, S12 and S13 speed or angle supervision, S14 too many missing pulses (drive switches to open loop).^[1][2]

Likely causes

• Loose, broken or noisy encoder cable
• Encoder option board fault or missing board
• Encoder direction opposite to the output frequency
• Encoder identification run not done (S9)
• Resolver pole or gear ratio settings wrong (S8)

First checks, in this order

1. Read the subcode in the fault time data (T.14).
2. Check the encoder cable connections and terminals, and the encoder option board.
3. Measure the encoder pulses.
4. S4: change the polarity so the encoder signal is positive with positive output frequency.
5. S8: check the OPTBC parameter Resolver Poles and any gear ratio parameters against the motor pole count.
6. S9: make an encoder identification run.

F42: Brake resistor overtemperature

What it means: The brake resistor overtemperature protection detected too heavy braking. NX subcodes: S1 internal brake chopper overtemperature, and for a brake chopper unit (BCU): S2 brake resistance too high, S3 too low, S4 not detected, S5 leakage (earth fault).^[1][2]

Likely causes

• Deceleration too fast for the brake resistor
• Brake chopper or resistor too small for the duty
• Wrong, missing or damaged brake resistor (BCU subcodes S2 to S5)

First checks, in this order

1. Reset the unit.
2. Lengthen the deceleration time.
3. Check that the brake chopper and resistor are sized for the braking duty; use an external brake resistor if needed.
4. BCU subcodes S2 to S5: check the resistor value, its connection and its insulation to earth.

F29 / 29: Thermistor fault

What it means: The motor thermistor input on an option board has detected rising motor temperature. NX subcodes: S1 thermistor input on the OPTAF board, S2 special application.^[1][2][6]

Drive response: Programmable: no action, alarm or fault

Likely causes

• Motor overheating from load or poor cooling
• Broken or loose thermistor wiring
• Thermistor input not used and not short circuited

First checks, in this order

1. Check motor cooling and load.
2. Check the thermistor connections.
3. If the thermistor input is not used, it must be short circuited.
4. Check the response: NX Response to thermistor fault (ID 732, P2.7.21 in the Standard application); VACON 20 P13.22.

29: ATEX thermistor

What it means: The ATEX thermistor input reports motor overtemperature (fault ID 280).^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Motor too hot
• Thermistor or wiring fault

First checks, in this order

1. Let the motor cool and check its cooling and load.
2. Check the thermistor and its connections, then reset.
3. If code 30 with ID 521 or 522 also appears, the ATEX thermistor input is open or short circuited: check that wiring.

F52 / 52: Keypad communication fault (NX, VACON 100) / Door Panel fault (VACON 20)

What it means: The link between the control panel (or PC tool) and the drive is lost. VACON 100 shows fault ID 1052 or 1352. On a VACON 20 it means the control place is the keypad but the door panel has been disconnected.^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Loose or damaged keypad cable or connector
• Keypad not seated properly
• Door-mounted panel unplugged while it is the control place (VACON 20)

First checks, in this order

1. Check the control panel connection and the panel cable.
2. Reseat the keypad.
3. VACON 20: check the connection between the option board and the control board.
4. If the panel is removed on purpose, move the control place away from the keypad.

F54 / 54: Slot fault (NX, VACON 20) / Slot A fault to Slot E fault (VACON 100)

What it means: An option board or its slot is faulty, or the board lost its connection to the control board. VACON 100 shows the slot in the fault ID: 1354 (A), 1454 (B), 1554 (C), 1654 (D), 1754 (E).^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Programmable: no action, alarm or fault

Likely causes

• Defective option board
• Board not fully seated in its slot
• Defective slot on the control board

First checks, in this order

1. With power off, check and reseat the option board.
2. Check the board and the slot.
3. Check the response: NX Response to slot fault (ID 734, P2.7.23 in the Standard application); VACON 100 P3.9.1.7.
4. If it comes back, contact your Danfoss distributor.

F12 / 12: Brake chopper supervision

What it means: The brake chopper monitoring found a problem: the brake resistor is missing or broken, or the chopper is faulty. VACON 100 shows fault ID 110 (hardware fault) or ID 111 Brake chopper saturation alarm.^[1][2][3]

Also on: VACON 100 INDUSTRIAL manual; not listed in the VACON 100 FLOW guide checked

Likely causes

• Brake resistor not connected
• Broken brake resistor
• Defective brake chopper

First checks, in this order

1. Check the brake resistor, its resistance and its cabling.
2. If they are in good condition, the resistor or the chopper is faulty: contact your Danfoss distributor.
3. VACON 100: check that P5.6.2.1 Brake Chopper Mode matches the installation.

F57 / 57: Identification

What it means: The motor identification run failed. VACON 100 fault ID 1057 is a general failure; IDs 1157, 1257 and 1357 mean the drive could not reach the required frequency during the run (frequency limits, acceleration time or current, torque and power limits).^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: NX: alarm (type A); VACON 100 and VACON 20: fault

Likely causes

• Start command removed before the identification run finished
• Motor not connected to the drive
• Load on the motor shaft
• VACON 100: maximum frequency too low, acceleration too slow to reach the frequency within 40 s, or limits set too low

First checks, in this order

1. Keep the start command on until the run is complete.
2. Check that the motor is connected.
3. Remove the load from the motor shaft if the run type needs it.
4. VACON 100: check minimum and maximum frequency, acceleration time, and current, torque and power limits.

F22 / 22: Parameter fault (NX) / EEPROM checksum fault (VACON 20)

What it means: The drive found a parameter save or checksum error in its memory. NX subcodes S1 to S13 tell which data block failed, for example S4 or S10 system parameter checksum error and S13 checksum error in the application parameter set.^[1][2][6]

Likely causes

• Faulty operation, for example power lost during a parameter save
• Component failure on the control board

First checks, in this order

1. Reset the fault and restart.
2. NX subcode S13: recommission the application and check the parameters.
3. If it comes back, contact your Danfoss distributor.

F25 / 25: Microprocessor watchdog fault (NX) / Microcontroller watchdog fault (VACON 20)

What it means: The processor watchdog reset the control electronics. NX subcodes: S1 CPU watchdog timer, S2 ASIC reset.^[1][2][6]

Likely causes

• Operation malfunction or electrical disturbance
• Defective component

First checks, in this order

1. Reset the fault and restart.
2. If it comes back, contact your Danfoss distributor.

25: Motor control fault

What it means: Start angle identification of the motor failed (fault ID 240 or 241). The manual says this fault is only used with a customer-specific application.^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Rotor moved during identification
• New start angle does not agree with the old value

First checks, in this order

1. Reset the fault and restart.
2. Increase the identification current.
3. Read the fault history source data for details.

F24: Counter fault

What it means: The values shown on the NX counters are not correct.^[1][2]

Drive response: Not stated in the guide

Likely causes

• Counter data error in the control unit

First checks, in this order

1. Treat the counter values (operating hours, energy) with caution.
2. Contact your Danfoss distributor if you need the counter data.

F26 / 26: Start-up prevented

What it means: The drive blocked a start because a run request was active at the wrong moment. NX subcodes: S1 run request on when a new application was downloaded, S2 start command on when returning to READY after Safe Disable, S30 run request given too quickly after a software or application change. VACON 100 (fault ID 250): run request on while new software, a parameter setting or another file was loaded.^[1][2][3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Start command left on during a software, application or parameter download
• Start command still on when STO or Safe Disable was cleared

First checks, in this order

1. Remove the run request, reset, and give a new start only when it is safe.
2. VACON 100: P3.9.1.15 Startup Prevented Fault (ID 15593) chooses fault or no action.

19: Power overload

What it means: The drive's output power is too high. VACON 100 fault ID 180 is the short-time supervision, ID 181 the long-time supervision.^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Load too high
• Drive too small for the application

First checks, in this order

1. Reduce the load.
2. Check the drive sizing against the real load.

F19: Current overload

What it means: Motor current overload warning on an NX drive.^[1][2]

Likely causes

• Motor current above the allowed level

First checks, in this order

1. Check the motor load and current.
2. Ask your Danfoss distributor for instructions.

F63 / 63: Quick stop (NX, VACON 20) / Quick Stop fault (VACON 100)

What it means: A quick stop command came from a digital input or the fieldbus. VACON 100 shows fault ID 1063, or ID 1363 Quick Stop alarm.^{[1][2][3][4][6]}

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: NX: alarm (type A); VACON 100: fault or alarm

Likely causes

• Quick stop input or fieldbus quick stop command activated

First checks, in this order

1. Find why the quick stop was activated and correct it, then reset.
2. VACON 100: check P3.5.1.26 Quick Stop Activation and the quick stop group P3.9.5.1 to P3.9.5.4 (response ID 744).

F58 / 58: Brake (NX) / Mechanical brake (VACON 100)

What it means: The real state of the mechanical brake differs from the brake control signal. On VACON 100 (fault ID 1058) this must last longer than the delay in P3.20.6.^[1][2][3]

Also on: VACON 100 INDUSTRIAL manual; not listed in the VACON 100 FLOW guide checked

Drive response: Programmable on NX

Likely causes

• Brake feedback switch or wiring fault
• Mechanical brake not opening or closing
• Brake delay or feedback settings wrong

First checks, in this order

1. Check the mechanical brake state and its connections.
2. VACON 100: check P3.5.1.44 and parameter group 3.20 Mechanical brake.
3. NX: check Response to brake fault (ID 1316) and Brake fault delays (ID 1317).

F18 / 18: Unbalance

What it means: Current or DC voltage is unbalanced between parallel power modules. NX subcodes: S1 current unbalance, S2 DC voltage unbalance. VACON 100 FLOW: ID 170 current unbalance, ID 171 DC voltage unbalance, ID 173 alarm, used only on MR11 and MR12.^[1][2][4]

Also on: VACON 100 FLOW guide (MR11, MR12); not listed in the VACON 100 INDUSTRIAL manual checked

Drive response: NX: alarm (type A); VACON 100: fault (IDs 170, 171) or alarm (ID 173)

Likely causes

• Motor cable or connection fault on one power unit
• DC link cable fault between power units (ID 171)
• Output filter problem

First checks, in this order

1. Check the motor cables and connections.
2. Check the DC link cables between the power units.
3. Check the output filters (dU/dt or sine filter).
4. Reset and restart; if it comes back, contact your Danfoss distributor.

F6: Emergency stop

What it means: A stop signal was given from an option board.^[1][2]

Likely causes

• Emergency stop circuit opened

First checks, in this order

1. Check the emergency stop circuit and the reason it was used.

F62: Run disable

What it means: The run enable signal is low, so the NX drive cannot run.^[1][2]

Likely causes

• Run enable input open or wiring fault

First checks, in this order

1. Check why the run enable signal is off and check its wiring.

F64: Input switch open

What it means: The drive's input (main) switch is open.^[1][2]

Drive response: Alarm (type A)

Likely causes

• Main switch of the drive open

First checks, in this order

1. Check the main power switch of the drive.

F37 / 37: Device changed (same type)

What it means: A board was replaced by the same type. NX: a new option board replaced the old one in the same slot. VACON 100: ID 361 power unit replaced by one of the same size; IDs 362 to 365 option board in slot B to E replaced by one used there before. Parameters are kept.^[1][2][3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Option board or power unit replaced during service

First checks, in this order

1. Reset the fault. The drive uses the old parameter settings.
2. VACON 100 ID 361: the drive reboots after the reset.

F38 / 38: Device added (same type)

What it means: An option board was added to a slot where the same board was used before. Parameters are kept. VACON 100 IDs 372 to 375 (slots B to E).^[1][2][3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Option board fitted again

First checks, in this order

1. Reset the fault. The device is ready and the drive uses the old parameter settings.

F39 / 39: Device removed

What it means: An option board was removed from its slot. VACON 100 IDs 382 to 385 (slots A or B to E).^[1][2][3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: VACON 100 fault history example shows it as Info

Likely causes

• Option board removed or not detected

First checks, in this order

1. Reset the fault. Refit the board if it is needed.

F40 / 40: Device unknown

What it means: An unknown or mismatching power unit or option board was connected. NX subcodes S1 to S7 cover unknown device, StarCoupler mismatch, control board EEPROM problems and old ASIC or power unit versions. VACON 100 shows fault ID 390.^[1][2][3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Board or power unit not supported by this control board or software

First checks, in this order

1. Check that the board type matches the drive and software.
2. Ask your Danfoss distributor for instructions.

F44 / 44: Device changed (different type)

What it means: An option board or power unit was replaced by a different type or power rating, so its parameters are not available. VACON 100: ID 431 power unit, IDs 433 to 435 option board in slots C to E.^[1][3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Board or power unit of a different type fitted

First checks, in this order

1. Reset the fault.
2. Set the option board parameters again, or the drive parameters if the power unit changed.
3. VACON 100 ID 431: the drive reboots after the reset.

F45 / 45: Device added (different type)

What it means: An option board (or power unit) of a different type was added, so no parameter settings are saved for it. VACON 100: ID 441 power unit, IDs 443 to 445 option board in slots C to E.^[1][2][3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• New type of board added

First checks, in this order

1. Reset the fault.
2. Set the parameters for the new board or power unit.

33: Fire mode enabled

What it means: Fire mode is on (fault ID 320), so drive protections are disabled or auto reset.^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Alarm, resets when fire mode ends

Likely causes

• Fire mode activated by its input or settings

First checks, in this order

1. Check the fire mode parameter settings and signals.
2. The alarm resets itself when fire mode is turned off.

66: Thermistor input 1 fault (also input 2, input 3)

What it means: A thermistor input reports rising motor temperature. Fault ID 1366 is input 1, 1466 input 2, 1566 input 3.^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Programmable: no action, alarm or fault

Likely causes

• Motor too hot from load or poor cooling
• Thermistor wiring fault
• Unused thermistor input left open

First checks, in this order

1. Check motor cooling and load.
2. Check the thermistor connection.
3. If the thermistor input is not used, short circuit it.
4. Check the response with P3.9.1.8 Thermistor Fault (ID 732).

101: Feedback supervision fault (PID1)

What it means: The PID feedback value stayed outside the supervision limits (P3.13.6.2 and P3.13.6.3) for longer than the delay (P3.13.6.4). Fault ID 1101.^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Process problem, for example a pump that cannot hold pressure
• Feedback sensor or wiring fault
• Supervision limits or delay set too tight

First checks, in this order

1. Check the process.
2. Check the feedback sensor and its signal.
3. Check the supervision limits and delay, and the response P3.9.1.10.

100: Soft fill timeout

What it means: The PID soft fill function did not reach the process value within its time limit (fault ID 1100). A broken pipe can be the cause.^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Broken or leaking pipe
• Soft fill level or time limit set wrong

First checks, in this order

1. Check the process and piping.
2. Check the parameters in menu M3.13.8 and the response P3.9.1.9.

109: Input pressure supervision

What it means: The input pressure signal (P3.13.9.2) is below the alarm limit P3.13.9.7 (fault ID 1109, alarm) or the fault limit P3.13.9.8 (fault ID 1409).^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Alarm (ID 1109) or fault (ID 1409)

Likely causes

• Low suction or inlet pressure
• Pressure sensor or wiring fault

First checks, in this order

1. Check the process.
2. Check the parameters in menu M3.13.9.
3. Check the input pressure sensor and its connections.

117: Flow switch

What it means: The flow switch feedback stayed inactive longer than the flow switch fault delay (fault ID 1117).^[4]

Also on: VACON 100 FLOW guide only (not in the VACON 100 INDUSTRIAL manual checked)

Likely causes

• Low or lost flow in the process
• Flow switch or wiring fault
• Delay set too short

First checks, in this order

1. Check the process.
2. Check the parameter settings.

111: Temperature fault 1 (VACON 100) / Temperature fault (VACON 20)

What it means: A temperature input from an option board is above its alarm limit or fault limit. VACON 100: fault ID 1315 above the alarm limit P3.9.6.2, ID 1316 above the fault limit P3.9.6.3 (inputs chosen in P3.9.6.1). VACON 20: temperature too low or too high on the OPTBH board.^[3][4][6]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: VACON 100: alarm (ID 1315) or fault (ID 1316)

Likely causes

• Real temperature rise in the measured equipment
• Sensor or wiring fault
• Temperature input not hardwired when no sensor is fitted

First checks, in this order

1. Find the cause of the temperature rise.
2. Check the temperature sensor and its connections.
3. If no sensor is connected, make sure the temperature input is hardwired.
4. VACON 100: check P3.9.6.1 to P3.9.6.4. VACON 20: check the temperature signal from the OPTBH board.

112: Temperature fault 2

What it means: A temperature input chosen in P3.9.6.5 is above its limit (fault IDs 1317 and 1318).^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Real temperature rise
• Sensor or wiring fault

First checks, in this order

1. Find the cause of the temperature rise.
2. Check the temperature sensor and connections.
3. Check P3.9.6.5 to P3.9.6.8.

68: Maintenance counter 1 alarm (also counter 1 fault, counter 2 alarm and fault)

What it means: A maintenance counter has passed its alarm limit (IDs 1301, 1303) or fault limit (IDs 1302, 1304).^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Alarm (IDs 1301, 1303) or fault (IDs 1302, 1304)

Likely causes

• Maintenance interval reached

First checks, in this order

1. Do the planned maintenance.
2. Reset the counter with B3.16.4 or the digital input set in P3.5.1.40.

76: Start prevented

What it means: The start command is blocked at the first power-up to stop the motor from turning by accident (fault ID 1076).^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Start command active at first power-up

First checks, in this order

1. Reset the drive. The parameter settings decide whether the drive must be restarted.

46: Real Time Clock

What it means: The real time clock battery voltage is low (fault ID 662).^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• RTC battery near the end of its life

First checks, in this order

1. Replace the battery.

47: Software updated

What it means: The drive software (full package or application) was updated (fault ID 663).^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Drive response: Notification

Likely causes

• Software update done

First checks, in this order

1. No action needed.

65: PC communication fault

What it means: The data connection between the PC and the drive is broken (fault ID 1065).^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• PC cable, adapter or terminal problem

First checks, in this order

1. Check the installation, cable and terminals between the PC and the drive.

69: Fieldbus mapping error (VACON 100 FLOW) / Fieldbus communication fault (VACON 100 INDUSTRIAL)

What it means: A value mapped to Fieldbus Process Data Out cannot be sent: the ID is not valid (1310), the value type cannot be converted (1311), or the 16-bit value overflows (1312).^[3][4]

Also on: Name differs between the two VACON 100 manuals; IDs are the same

Likely causes

• Wrong ID in the fieldbus data mapping
• Mapped value too large for 16 bits

First checks, in this order

1. Check the parameters in the fieldbus data mapping menu.

77: > 5 connections

What it means: More than 5 fieldbus or PC tool connections are active; only 5 are allowed at the same time (fault ID 1077).^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Too many simultaneous fieldbus or PC connections

First checks, in this order

1. Keep 5 active connections and remove the others.

78: Identification ongoing

What it means: The drive is running the motor identification (fault ID 1078).^[4]

Also on: VACON 100 FLOW guide only (not in the VACON 100 INDUSTRIAL manual checked)

Drive response: Notification

Likely causes

• Identification run started

First checks, in this order

1. Wait for it to finish. Removing the start command stops the run; a new start command is needed after it completes.

105: Feedback supervision fault (ExtPID)

What it means: The external PID controller feedback stayed outside its supervision limits (P3.14.4.2 and P3.14.4.3) for longer than the delay (P3.14.4.4). Fault ID 1105.^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Process problem
• Feedback sensor or wiring fault
• Limits or delay set too tight

First checks, in this order

1. Check the process.
2. Check the supervision limits, the delay and the response P3.9.1.11.

113: Pump running time

What it means: In a multi-pump system, one or more pump run time counters passed the user alarm limit (fault IDs 1113, 1313).^[4]

Also on: VACON 100 FLOW guide only (not in the VACON 100 INDUSTRIAL manual checked)

Drive response: Alarm

Likely causes

• Pump service interval reached

First checks, in this order

1. Do the maintenance, reset the run time counter and reset the alarm.

118: AHF Over Temp

What it means: The advanced harmonic filter signalled an overtemperature fault through a digital input (fault ID 1118).^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Harmonic filter overheated
• Filter temperature contact or wiring fault

First checks, in this order

1. Check the advanced harmonic filter, its cooling and its signal wiring.

119: Auto Cleaning

What it means: The motor did not reach the expected speed reference during the pump auto cleaning sequence (fault ID 1119).^[4]

Also on: VACON 100 FLOW guide only (not in the VACON 100 INDUSTRIAL manual checked)

Likely causes

• Blocked pump or process
• Auto cleaning settings not suited to the pump

First checks, in this order

1. Check the process.
2. Check the auto cleaning parameter settings.

300: Unsupported

What it means: The application (fault ID 700) or an option board or slot (fault ID 701) is not compatible with the drive.^[3][4]

Also on: VACON 100 INDUSTRIAL and VACON 100 FLOW manuals list the same code

Likely causes

• Wrong application loaded
• Option board not supported in that drive or slot

First checks, in this order

1. ID 700: replace the application.
2. ID 701: remove the option board.

F34: CAN bus communication

What it means: A message sent on the CAN bus was not acknowledged.^[1][2]

Likely causes

• Other CAN device missing, off or set up differently
• CAN cable fault

First checks, in this order

1. Make sure another device with the same configuration is on the bus.
2. Check the CAN cable.

F35 / 35: Application (NX) / Application fault (VACON 20)

What it means: The application software is not working properly.^[1][2][6]

Likely causes

• Problem in the application software

First checks, in this order

1. Ask your Danfoss distributor for instructions.
2. If the application is custom, have the programmer check it.

F36: Control unit

What it means: The software needs a newer version of the NX control unit.^[1][2]

Likely causes

• Control unit too old for the loaded software

First checks, in this order

1. Change the control unit, or load software that suits it.

F49: Division by zero in application

What it means: A division by zero happened in the application program.^[1][2]

Likely causes

• Application program error

First checks, in this order

1. If it appears in Run state again, contact your Danfoss distributor.
2. If the application is custom, have the programmer check it.

F56: Measured Temperature

What it means: Temperature measurement fault on option board OPTBH or OPTB8: the temperature is over the set limit, or the sensor is disconnected or shorted.^[1][2]

Likely causes

• Real temperature rise
• Sensor disconnected
• Short circuit in the sensor or wiring

First checks, in this order

1. Find the cause of the temperature rise.
2. Check the sensor and its wiring.
3. Check the response: TBoard Fault Response (ID 740).

F65: Measured Temperature

What it means: Second NX code for a temperature measurement fault on option board OPTBH or OPTB8: limit exceeded, sensor disconnected or short circuit.^[1][2]

Likely causes

• Real temperature rise
• Sensor disconnected or shorted

First checks, in this order

1. Find the cause of the temperature rise or sensor fault.
2. Check the sensor and its wiring.

F59: Follower communication

What it means: The system bus or CAN link between master and follower drives is broken.^[1][2]

Likely causes

• Optical fiber or CAN cable fault
• Option board settings wrong

First checks, in this order

1. Check the option board parameters.
2. Check the optical fiber or CAN cable.

F74: Follower fault

What it means: In master and follower operation, one or more follower drives tripped.^[1][2]

Likely causes

• Fault on a follower drive

First checks, in this order

1. Find and correct the fault on the follower, then reset.

F60: Cooling

What it means: The external cooling system failed; this normally comes from the heat exchanger unit.^[1][2]

Likely causes

• Heat exchanger or external cooling failure

First checks, in this order

1. Check the external cooling system for the cause.

F61: Speed error

What it means: The motor speed does not match the reference.^[1][2]

Likely causes

• Encoder connection fault
• Permanent magnet motor went past its pull-out torque

First checks, in this order

1. Check the encoder connection.
2. Check the load on a permanent magnet motor.
3. Check Speed Error Fault Function (ID 752).

F70: Active filter fault

What it means: A digital input set for the active filter (P2.2.7.33 in the guide) reports a fault.^[1][2]

Drive response: Programmable

Likely causes

• Fault in the active filter

First checks, in this order

1. Clear the fault on the active filter.
2. Check Response to Active Filter Fault (ID 776).

27: Back EMF protection

What it means: The VACON 20 detected that a magnetized (permanent magnet) motor was already turning when the start command was given.^[6]

Likely causes

• Rotating PM motor at start

First checks, in this order

1. Make sure a PM motor is not turning when the start command is given.

34: Internal bus communication

What it means: Internal bus communication on the VACON 20 failed.^[6]

Likely causes

• Electrical interference nearby
• Defective hardware

First checks, in this order

1. Look for interference sources and check earthing.
2. If it comes back, contact your Danfoss distributor.

55: Wrong run fault (FWD/REV conflict)

What it means: Run forward and run reverse signals are both high at the same time.^[6]

Drive response: Programmable with P13.23

Likely causes

• Both direction commands active together
• Control wiring or PLC logic error

First checks, in this order

1. Check I/O control signal 1 and I/O control signal 2.
2. Check P13.23 FWD/REV conflict supervision.