Drive diagnostic procedures
Structured investigation paths for high-risk drive faults, board regions and post-repair power-up decisions.
Blinking, partial or unstable VLT 2800 display after power-up, keypad swap or repeated power cycling.
Alarm 13 overcurrent or Alarm 14 earth fault on a VLT 2800 / 2900 compact drive during start, ramp, run or bench test.
Alarm 16 short circuit, repeat output-stage failure or post-repair uncertainty on compact Danfoss VLT 2900 hardware.
SIMOREG 6RA70 fails, refuses or interrupts an optimization run during commissioning, motor replacement, parameter restore or feedback work.
The DC motor hunts, overspeeds, fails speed optimization, shows unreliable actual speed or behaves differently after tachometer, encoder, motor or control-board work.
The 6RA70 cannot save commissioning data, refuses optimization, has unknown parameters after a board change, or arrives with a donor CUD1 / power-interface history.
SIMOREG 6RA70 reports F005 or cannot prove the selected DC motor field circuit.
6RA70 reports F030, trips on armature current build-up, or indicates commutation / current behavior that cannot be explained from the panel alone.
The PMU/operator interface is dark, flickers, resets, or the converter cannot provide stable diagnostic access.
DCS800 displays F521 / FieldAck or cannot confirm the field acknowledgement for the selected DC motor.
DCS800 D5-D7 converter has dead control electronics, reset behavior, unstable status display, unreliable FieldAck context or suspected SDCS board-chain failure.
A service request asks whether SDCS-CON-4, SDCS-POW-4 or SDCS-PIN-51 should be repaired, replaced, sourced from a donor converter or used as part of a modernization decision.
F521, field ready lost, field-exciter communication context or a missing acknowledgement appears on a DCS800 installation with an internal or external field-exciter route.
ACS800 SHORT CIRC / 2340 appears during enable, first PWM, acceleration, load operation, or after an output-stage repair.
An ACS800 reports 2340 again after an IGBT, power module, AGDR assembly or output-stage repair, or the same phase leg repeatedly fails.
An ACS800 displays PPCC LINK / 5210, with or without a module suffix, after power-up, reset, output enable or a previous board/module repair.
The ACS800 panel is dark, unstable, externally powered, or reports PPCC-related trouble during a control-power transition.
A PPCC LINK case, cabinet drive or parallel inverter arrangement points toward a specific interface branch, INT/AINT board or module route.
E07 appears during deceleration, stop, lowering/overhauling motion or high-inertia load operation, often after a ramp change, resistor installation or repeated reset attempt.
E07 remains after ramp and resistor evidence is reviewed, or the DC-bus / brake behaviour does not match the machine event timing.
SJ300 or L300P reports E01, E02, E03 or E04 overcurrent, with the trip tied to constant speed, deceleration, acceleration or another operating condition.
E01-E04 persists after the motor/cable/load route is proven, or the drive has repeated overcurrent after a power-board / output-module repair.
E09 undervoltage, dark keypad, intermittent display reset, no readable trip history, or an old SJ300/L300P that fails after input disturbance or fuse/contactor work.
A Parker / Eurotherm 514C powers up but does not build safe armature voltage or usable torque.
A 514C application has no torque, weak torque or unsafe field uncertainty, especially where a separate field controller or retrofit wiring is present.
A 514C clears fuses, trips protection or is suspected of SCR bridge failure.
SPEED FBK, ENCODER FAILED, unstable speed regulation, overspeed tendency or load-related speed collapse appears on a 590P / 591P DC drive.
The 590P / 591P is using armature-voltage feedback and the machine shows weak speed regulation, load-related speed collapse, field-weakening instability or a suspected need for tach / encoder feedback.
OVER I TRIP appears during enable, autotune, acceleration, reversing or without believable motor torque, and the technician must separate real current from feedback or tuning evidence.
FIELD FAIL appears when the DC motor field should be established, or the machine cannot build field current before armature demand.
MISSING PULSE appears, armature current is uneven, or torque is absent even though enable and command evidence are present.
The VLT reports Alarm 7 / DC-link overvoltage or a DC-voltage warning when the machine decelerates, performs quick stop, lowers a load or stops a high-inertia fan, pump or conveyor.
A VFD module has already been replaced once or more and the drive still fails, trips, produces unbalanced output, or destroys the replacement module.
A legacy integrated module appears to have rectifier/input-side damage while the inverter section may not show the same evidence.
The drive reports OC/GF-style behaviour or cuts gate pulses rapidly in a way that points to the module protection path rather than a simple parameter trip.
A MICROMASTER drive trips on F0001 overcurrent or F0002 overvoltage during start, acceleration, deceleration or OFF3 fast stop.
A MICROMASTER drive reports F0003 undervoltage, resets during start, or loses DC-bus credibility under load.
PowerFlex drive reports F12 hardware overcurrent, F13 ground fault, or both around the same start/run event.
PowerFlex trips on F5 DC bus overvoltage or F4 undervoltage during power-up, line sag, acceleration or deceleration.
PowerFlex reports DPI port loss, HIM loss or communication loss to a connected port device.
Unidrive SP/M reports OI.AC or trips during enable, acceleration, load change or closed-loop instability.
Unidrive reports Over Volts during deceleration, lowering, stop, winder unwind or unstable closed-loop operation.
Unidrive reports PS.24V, thermal feedback symptoms, O.ht/O.ht1 or feedback instability with option modules and external control wiring.
ATV61/ATV71 trips on OCF overcurrent or SCF short circuit at start, ramp or load.
ATV61/ATV71 reports OSF overvoltage or USF undervoltage during power-up, line transition, run, load change, stop or deceleration.
Drive is ready but does not run, runs from keypad but not terminals, or speed reference is missing/unstable.
Danfoss VLT reports alarm 14 earth fault or alarm 16 short circuit.
Danfoss VLT reports alarm 4 or shows input phase instability.
Danfoss VLT reports alarm 29 during operation or immediately after power-up.
Danfoss VLT trips on overvoltage during deceleration, stop or load lowering.
ACS510/ACS550 reports DC UNDERVOLT 3220, LINE CONV ff51, weak display or input-side converter abnormality.
ACS510/ACS550 trips on OVERCURRENT 2310 at start, during acceleration or under load.
A technician wants to clear a stored ABB drive fault or request help without losing the event trail.
MASTERDRIVES reports motor-temperature warning/trip or inconsistent KTY/PTC sensor behaviour.
Brake does not release/close correctly, load slips, or the drive trips during brake sequence on a MASTERDRIVES application.
Drive line power is present, but the keypad is dark, flashing or repeatedly restarting.
Drive reports undervoltage/precharge fault, blows input fuses or shows no-display symptoms with uncertain DC-link charging.
Overcurrent trip appears immediately at run command, during acceleration or before stable speed is reached.
Drive trips on DC bus overvoltage when stopping, lowering, braking or reducing speed.
Ground fault, earth fault or leakage trip occurs when output voltage is applied.
Replacement IGBT, IPM or output module fails again during power-up, enable or early load testing.
OVER I TRIP appears at enable, start, autotune or without expected armature current.
FIELD FAIL appears when the shunt field should be established.
Missing pulse, uneven armature output or no torque suggests firing-path evidence is required.
SPEED FBK or ENCODER alarms appear, or speed regulation becomes unstable.
The drive has no display, resets, or loses control-interface power.
The analog 514C drive powers but armature output or motor torque is absent.
A 514C application lacks field current or has no safe motor torque.
Fuses open or protective devices trip around the analog DC controller.
A legacy 590P, 591P or 514C failure must be evaluated against downtime, configuration and replacement risk.
E01-E04 overcurrent trip with operating-condition evidence.
E05 overload trip or thermal load behavior.
E07 overvoltage or E09 undervoltage.
Blank keypad, reset or no code available.
Legacy SJ300 repair, used motherboard or replacement-drive decision.
Blinking, partial or non-initializing VLT 2800 display after keypad replacement or power cycling.
Warning/Alarm 13 or Alarm 14 during run command, acceleration or output energization.
Alarm 16 current short-circuit, repeat module failure or post-IGBT repair risk.
Dead panel, no fault history access or suspected power-board auxiliary supply failure on an inactive NXL unit.
NXL F1 overcurrent or F3 earth fault after start command or under load.
F2 overvoltage event during deceleration, supply transients or regenerative load conditions.
A discontinued or legacy compact drive has a board-level symptom and the technician must choose repair, used replacement or retrofit.
F005 / overvoltage trip, especially at deceleration or repeated startup attempts.
F004 undervoltage, power-loss event, or large-frame drive that will not sustain DC-bus energy.
F081 / Comm Loss, intermittent PLC or HMI control loss, or communication returning automatically after a fault.
No display, no keypad initialization, or control electronics dead while input power is expected.
Large-frame PowerFlex 400 stopped by bus, output, communication or no-display issue where repair, used replacement or modernization must be chosen.
SCF1, SCF2/SCF3 or related motor short-circuit / IGBT short-circuit indication.
Blank/off display, HMI cannot read information, or drive appears dead from the keypad.
USF mains-undervoltage or low DC-bus condition.
Suspected failed ATV71 power board after SCF, USF, no display or visible internal damage.
No display, unstable keypad/control logic or suspected auxiliary-power failure on a PDL UE Frame drive.
Bus-related trip, abnormal startup, precharge concern, overvoltage/undervoltage symptom or damage around DC-link components.
Trip at output enable, suspected IGBT gate-drive fault, comparator/protection trip or repeated module damage.
A legacy PDL drive has repeated failures, uncertain parts availability or a repair/upgrade decision point.
EV2000 shows POFF, no display, E004-like control behavior or fails to initialize after power is applied.
EV2000 displays E019, may not reset, or reports current-detection fault without real output current.
EV1000 small-board drive has no display or panel initialization after power-up.
Drive display recovers after IGBT/IPM or control-board repair, but output is absent, E019 appears, or run-command test is unsafe.
HW Power Supply indication, unstable control behavior or a suspected internal auxiliary-power failure.
HW Ground Fault appears at enable or while commanding motor output.
BUS Overvoltage or Bus Undervoltage appears during energization, acceleration, running or deceleration.
Input power is available but the EDS1000-2S0015 display/control response is absent or low-voltage functions are unstable.
The drive electronics appear powered but U/V/W output cannot be established safely or protection occurs on an attempted start.
Current-related protection or implausible control behaviour remains after external load and obvious power-stage conditions have been considered.
SV185iS5-4N0 has suffered IGBT/CPU damage or presents unstable low-voltage rails; the 24 V control supply is suspected of rising above its intended level.
An iS5 drive has destroyed a CPU/control board after IGBT repair or a donor CPU board is being considered for testing.
The FR-A740 reports E.OC1 during acceleration, immediately on start or after an output-stage repair.
The drive runs but trips with E.OV3 while decelerating or stopping an inertial load.
An FR-A740 output module has failed or been replaced, and the technician must decide whether the drive can be energised safely.
An A1000 reports SC or GF and the technician must separate motor/cable faults from internal drive damage.
A 616G3 55 kW drive under controlled post-repair testing produces a bright lamp indication after the run command, suggesting a shorted IGBT module.
A Yaskawa inverter has suffered output-module damage or repeat SC/GF-type trips after repair.
An ACS800 displays PPCC LINK / 5210 or a parallel inverter module reports a PPCC link suffix.
An ACS800 reports SHORT CIRC / 2340, particularly after a failed module or when a replacement power component is under consideration.
A DCS800 DC drive displays F521 because field acknowledgement for the selected motor is missing.
A DCS800 D5–D7 converter shows dead or unstable control electronics, unexplained reset behavior or suspected board-chain failure.
A drive has been removed from service or is being inspected before commissioning, wiring verification or deeper repair.
The TD900 presents E019 or a suspected false current indication.
POFF is displayed at power-up or appears only after a run command.
A failed power module has been replaced, or a drive experienced a destructive power-stage event.
A MASTERDRIVES system stops with F002, F006 or F008, or cannot progress safely from precharge to operation.
The unit reports F011 or a suspected output-stage current event after start, acceleration or previous module repair.
A legacy MASTERDRIVES unit cannot be parameterized reliably, communication is lost, or a synchronized drive system no longer exchanges expected data.