Toshiba VFD Fault Codes

OC1: Overcurrent during acceleration

What it means: Output current went above the trip level while the motor was speeding up, so the drive switched its output off and the motor coasted. Q9 Plus and P9 trip at about 340% of rated current (320% on drives above 100 HP); the E3 manual gives 145% of rated FLA (190% above 100 HP).^{[1][2][3][4][5][6][7][8]}

Also on: G7 fault screen: Overcurrent During Acceleration. Q9 fault screen: Over-Current Acc.

Likely causes

• Acceleration time too short for the load or inertia
• Phase to phase short or ground fault in the motor or motor cable
• Torque boost or V/f pattern set too high for the motor
• Drive restarted into a motor that was still coasting after a momentary power loss
• Jammed machine or a mechanical brake still applied
• Low impedance or high speed motor, or a very long motor cable

First checks, in this order

1. Increase the acceleration time: acc (S15, nC3), ACC (AS3), F009 Acceleration Time 1 (Q9 Plus, P9, G7), ACC1 (E3).
2. Lower manual torque boost vb, or enter the motor nameplate data (F415 motor rated current) and run auto-tuning with F400.
3. If the drive restarts into a spinning motor, enable auto-restart F301 and ride-through F302.
4. Disconnect the motor leads and megger the motor and cable; look for phase to phase shorts.
5. Check that the machine turns freely and any mechanical brake releases before the drive starts.
6. On long motor cables, lower the carrier frequency F300 (AS3) or add an output AC reactor (S15, nC3).

OC2: Overcurrent during deceleration

What it means: Output current went above the trip level while the motor was slowing down.^{[1][2][3][4][5][6][7][8]}

Also on: G7 fault screen: Overcurrent During Deceleration. Q9 fault screen: Over-Current Dec.

Likely causes

• Deceleration time too short
• Phase to phase short or ground fault on the output side
• Jammed machine or a mechanical brake applied while running
• Low inductance motor or a very long motor cable

First checks, in this order

1. Increase the deceleration time: dec (S15, nC3), dEC (AS3), F010 Deceleration Time 1 (Q9 Plus, P9, G7), DEC1 (E3).
2. Megger the motor and motor cable with the leads disconnected from the drive.
3. Check the machine and the brake.
4. On the E3, a braking resistor across PA and PB, or ACC/DEC PATTERN #1 option 1 (automatic accel/decel), can help.
5. On long motor cables, lower the carrier frequency F300 (AS3) or add an output AC reactor (S15, nC3).

OC3: Overcurrent during constant speed operation

What it means: Output current went above the trip level while the drive was running at a fixed speed, usually from a sudden load change.^{[1][2][3][4][5][6][7][8]}

Also on: G7 fault screen: Overcurrent During Run. Q9 fault screen: Over-Current Run.

Likely causes

• Sudden load fluctuation or an abnormal load (something stuck in the machine)
• Drive running hot (Q9 Plus, P9)
• Short or ground fault in the motor or cable
• Low inductance motor or a very long motor cable

First checks, in this order

1. Check the driven machine for jams, binding or shock loads and reduce load swings.
2. Megger the motor and motor cable.
3. Check drive cooling and ambient temperature.
4. On the E3, Toshiba suggests mechanical damping or an output line reactor for severe load swings.
5. On AS3, lower F300 carrier frequency; if exciting forcing is used, lower F456.

OCL: Overcurrent (load side at start-up)

What it means: At start the drive measured a short on its output side: output terminals, motor cable or motor windings. Q9 Plus calls it Output Short; on P9 it is listed together with the OCA1 to OCA3 phase overcurrent trips.^{[1][2][3][4][5][6][7][8]}

Also on: G7 fault screen: Load End Short Circuit. Q9 fault screen: Output Short.

Likely causes

• Short circuit or damaged insulation in the output wiring or the motor
• Motor with a very low impedance
• Power factor correction capacitors on the motor side (E3)
• Starting into a rotating motor (Q9 Plus)

First checks, in this order

1. Disconnect the motor leads from U, V and W and megger the motor and cable.
2. Remove any power factor correction capacitors from the motor circuit.
3. Check the output terminals and wiring for a short.
4. For low impedance motors, set short circuit detection at start F613 to 2 or 3 (S15, nC3, AS3); on the E3 see Item 169 OUTPUT SHORT-CIRCUIT DETECTION SELECT.

OCA1 / OCA2 / OCA3: U-phase / V-phase / W-phase overcurrent

What it means: The drive detected a short or very low impedance in one output phase: U (OCA1), V (OCA2) or W (OCA3). The AS3 and E3 manuals tie it to a failed IGBT (power transistor) in that phase.^{[1][2][3][4][5][8]}

Also on: G7 fault screen: U Phase Short Circuit, V Phase Short Circuit, W Phase Short Circuit. Q9 fault screen: U-Phase OC, V-Phase OC, W-Phase OC.

Likely causes

• Failed IGBT in the drive's output stage
• Short or very low impedance on that output lead or motor phase

First checks, in this order

1. Disconnect the motor and megger the motor and cable phase by phase.
2. If the trip repeats with the motor disconnected, the power section needs repair: contact your Toshiba distributor or TIC Customer Support.

OCA: Overcurrent at start-up (arm overcurrent)

What it means: At start-up the drive detected overcurrent inside its own power section. Toshiba lists a defective main circuit element as the cause.^[6][7]

Likely causes

• Defective main circuit element (power module) in the drive

First checks, in this order

1. Megger the motor and output cable to rule out an external short (an external short normally shows as OCL).
2. Contact your Toshiba distributor; the drive needs service.

OP1: Overvoltage during acceleration

What it means: DC bus voltage went too high while the motor was speeding up. On the E3 the trip level is 393 V DC (230 V drive) or 787 V DC (460 V drive).^{[1][2][3][4][5][6][7][8]}

Also on: G7 fault screen: Overvoltage During Acceleration. Q9 fault screen: Over-Voltage Acc.

Likely causes

• Input voltage high or fluctuating: a large supply (500 kVA or more; 200 kVA on nC3), power factor capacitors switching, or thyristor equipment on the same line
• Drive restarted into a coasting motor after a momentary power loss

First checks, in this order

1. Measure the input voltage and check it is inside the drive rating.
2. Install an input AC reactor.
3. Enable auto-restart F301 and ride-through F302 if the drive restarts into a spinning motor.

OP2: Overvoltage during deceleration

What it means: DC bus voltage went too high while the motor was slowing down, because the load fed more energy back to the drive than it could absorb.^{[1][2][3][4][5][6][7][8]}

Also on: G7 fault screen: Overvoltage During Deceleration. Q9 fault screen: Over-Voltage Dec.

Likely causes

• Deceleration time too short for the load inertia
• Overvoltage limit or stall protection switched off
• No braking resistor, or the resistor value too high
• Input voltage high or fluctuating

First checks, in this order

1. Increase the deceleration time (dec, dEC, F010 or DEC1).
2. Turn the overvoltage limit back on: F305 set to 0, 2 or 3 (S15, nC3, AS3); on the E3 set Item 164 overvoltage stall protection to option 0.
3. Fit a braking resistor and set it up (F304, F308, F309 on Q9 Plus and P9; F309 capacity on S15 and AS3).
4. Check the input voltage and add an input AC reactor if it spikes.

OP3: Overvoltage during constant speed operation

What it means: DC bus voltage went too high while running at a fixed speed, usually because the load drives the motor faster than the output frequency.^{[1][2][3][4][5][6][7][8]}

Also on: G7 fault screen: Overvoltage During Run. Q9 fault screen: Over-Voltage Run.

Likely causes

• Overhauling load putting the motor into regeneration
• Input voltage high or fluctuating
• Load fluctuations
• AS3: supply grounded at a point other than neutral, for example a corner grounded delta

First checks, in this order

1. Install a braking resistor (or braking module on nC3).
2. Check the input voltage and add an input AC reactor.
3. On AS3 with a corner grounded supply, disconnect the grounding capacitor as the manual describes (section 2.3.4).
4. On the E3 with presses or pump jacks, contact Toshiba for special programming.

OL1: Inverter overload

What it means: The drive's own overload model (current over time) reached its limit, so it tripped to protect itself. On S15, nC3 and AS3 a reset is refused for about 30 seconds of virtual cooling time.^{[2][3][4][5][6][7][8]}

Also on: E3 uses OLIN for this trip. G7 and Q9 fault screen: ASD Overload.

Likely causes

• Acceleration time too short
• DC braking current or time too large
• V/f setting wrong for the motor
• Restart into a coasting motor after a momentary stop
• Load too large for the drive rating, or a high carrier frequency

First checks, in this order

1. Increase the acceleration time.
2. Reduce DC braking current F251 and DC braking time F252.
3. Check the V/f pattern (Pt) against the machine.
4. Enable auto-restart F301 and ride-through F302.
5. Lower PWM carrier frequency F300 to 4 kHz or less (S15, nC3), or fit a larger drive.

OL2: Motor overload

What it means: The drive's electronic thermal model says the motor has carried too much current for too long and may overheat. On S15 and AS3 a reset is refused for about 120 seconds.^{[2][5][6][7][8]}

Also on: E3 uses OLMT for this trip. G7 fault screen: Motor Overload.

Likely causes

• Motor locked or the load beyond what the motor can deliver
• Long running at low speed on a self cooled motor
• Motor thermal settings not matched to the motor
• V/f setting wrong

First checks, in this order

1. Check the driven load and that the motor turns freely.
2. Set the motor overload protection to the motor nameplate: olm and thr (S15, nC3), OLM and tHrA (AS3), F600 Motor Overload Protection Level 1 (P9).
3. Check the V/f pattern setting.
4. Wait out the cooling time before resetting.

OLIN: Inverter overloaded trip

What it means: E3 only: the drive output stayed above 100% of its rated current for too long. Toshiba's example is 110% for 60 seconds or 150% for 0.5 seconds.^[1]

Also on: Later Toshiba drives use OL1 for this trip.

Likely causes

• DC injection braking current or time too large
• Carrier frequency above 8 kHz
• Seized motor or load bearings
• One input phase missing
• Drive undersized for the load

First checks, in this order

1. Reduce Item 166 DC INJECTION CURRENT and Item 167 DC INJECTION TIME.
2. Set the PWM carrier frequency (Item 98) below 8 kHz.
3. Set Item 14 OVERLOAD SELECTION to option 1 or 3 (soft stall) on variable torque loads.
4. Check voltage on all three input phases and check the bearings.
5. Try True Torque Control, or fit a larger drive.

OLMT: Motor overloaded trip

What it means: E3 only: the drive calculates that the motor drew too much current for too long and is in danger of overheating.^[1]

Also on: Later Toshiba drives use OL2 for this trip.

Likely causes

• Motor overloaded or running long at low frequency
• Motor overload settings (Items 178 to 181) not matched to the motor

First checks, in this order

1. Check the motor load.
2. Check Items 178 to 181; if the trip happens at low frequency, check Item 179 OVERLOAD REDUCTION START FREQUENCY.
3. Check Item 180 MOTOR 110% OVERLOAD TIME LIMIT.
4. Only if the motor has its own thermal protection, Item 181 options 2 or 3 turn this protection off.

OL3: Main module overload

What it means: The power module (IGBT) overload model reached its limit, typically from heavy current at low speed (about 15 Hz or below) with a high carrier frequency. No virtual cooling time applies. AS3 calls it Overload (IGBT).^[6][7][8]

Likely causes

• High carrier frequency with heavy load at low speed
• Starting a coasting motor from 0 Hz
• AS3: exciting forcing set too high

First checks, in this order

1. Lower PWM carrier frequency F300, or switch on automatic carrier reduction with F316.
2. Raise the operating frequency or reduce the load.
3. Use auto-restart F301 when starting a motor that is still turning.
4. AS3: lower stall prevention level F601 or F185, and lower F456 exciting forcing level.

OLr: Dynamic braking resistor overload

What it means: The braking resistor overload model reached its limit, so the drive tripped before the resistor overheats. On S15 and AS3 a reset is refused for about 20 seconds.^{[1][2][5][6][8]}

Also on: G7 fault screen: Dynamic Braking Resistor Overload.

Likely causes

• Deceleration time too short
• Braking duty too heavy for the resistor
• Resistor value or capacity set wrong in the drive

First checks, in this order

1. Increase the deceleration time.
2. Fit a higher wattage resistor and set its capacity: F309 (S15, AS3), F308 and F309 (P9).
3. E3: check Item 162 BRAKING RESISTOR VALUE and Item 163 BRAKING RESISTOR CAPACITY.
4. P9: check the over-voltage stall setting.

OCr: Dynamic braking resistor overcurrent

What it means: Too much current in the braking circuit, often a failed braking transistor (IGBT7) or a resistor that is missing, shorted or below the minimum ohm value. On AS3 (VFAS3-4220PC to 4750PC and 4160KPC to 4280KPC) this trip clears only by switching power off and on.^[1][2][5][8]

Also on: G7 fault screen: Dynamic Braking Resistor Overcurrent.

Likely causes

• Braking transistor IGBT7 damaged
• Resistor below the minimum allowed ohms, or wired wrong in series or parallel
• Short between PB and PC/- (AS3)
• Braking enabled with no resistor connected (AS3, P9)
• Input voltage above specification

First checks, in this order

1. Measure the resistor ohms at PA and PB and compare with the minimum in the manual.
2. Check the series and parallel wiring of multiple resistors.
3. If no resistor is needed, set F304 to disabled (AS3).
4. E3: check the DC bus fuse; if it is open, check the output transistors.
5. A failed IGBT7 needs authorized Toshiba service.

OH: Overheat

What it means: The drive heatsink or internal temperature went too high (E3: heatsink above 90 °C). The drive checks its own temperature and will not reset until it has cooled.^{[1][2][3][4][5][6][7][8]}

Also on: G7 fault screen: Overheat. On Q9, Q9 Plus, P9 and G7 an OH (Over-Heat) alarm warns first.

Likely causes

• Cooling fan failed or at end of life
• Ambient temperature outside the rated range
• Vents blocked or not enough space around the drive
• Heat sources too close, or the enclosure too small
• Heavy load or high carrier frequency
• Failed temperature sensor (trip right after power-up in a cool room)

First checks, in this order

1. Check that the cooling fan runs; if it does not, have it replaced.
2. Clean the heatsink and vents and restore the clearances.
3. Measure the ambient temperature in the cabinet.
4. Reduce the load or the carrier frequency F300; AS3 can reduce carrier automatically with F316.
5. Let the drive cool before resetting.

OH2: External thermal trip

What it means: An external thermal device, such as a motor thermostat or PTC wired to the drive or an option board, reported overtemperature. Names differ: External Overheat (P9), Option Over-Heat (Q9 Plus), Thermal fault stop command from external device (S15), External thermal trip (AS3).^{[3][4][5][6][8]}

Also on: Q9 fault screen: Option Over-Heat.

Likely causes

• Motor running hot (overload, poor cooling)
• Sensor or sensor wiring fault

First checks, in this order

1. Check that the motor current is not above its rated current, and check motor cooling.
2. Check the sensor and its wiring.
3. P9: input at TB3 TH1(+) and TH1(-), set by F637. Q9 Plus: PTC1 or PTC2, F637 and F638. S15 and AS3: input terminal function 46 or 47.

MOFF: Undervoltage in main circuit

What it means: The main circuit (DC bus) voltage is low or the input power is missing. The drive shows MOFF as a warning; it trips only if the undervoltage trip (UP1) is enabled.^{[1][2][3][4][5][6][7][8]}

Also on: Q9 alarm screen: Main Under-Volts.

Likely causes

• Low or missing three phase input voltage
• Shorting bar between P0 and PA/+ missing or loose
• Failed rectifier module (Q9 Plus)
• Loss of externally supplied control power (P9)
• Internal fault if the supply measures normal (S15)

First checks, in this order

1. Measure the supply voltage at R, S and T.
2. Check the shorting bar between P0 and PA/+.
3. If the supply is normal and MOFF stays, the drive needs repair.

UP1: Undervoltage fault (main circuit)

What it means: The main circuit voltage stayed too low while running and the undervoltage trip is enabled. E3 levels: below 217 V DC (230 V drive) or 413 V DC (460 V drive) for longer than the detect time.^{[1][2][5][6][7][8]}

Also on: G7 fault screen: DC Bus Undervoltage. Q9 and Q9 Plus show Main Under-Volts (MOFF) as an alarm.

Likely causes

• Low input voltage
• Momentary power failure longer than the detection time (F628 on P9)
• Undervoltage trip enabled on a supply with frequent dips

First checks, in this order

1. Measure the input voltage under load.
2. Check the undervoltage trip selection: F627 (S15, nC3, AS3), Items 184 and 185 (E3).
3. For short dips, Toshiba suggests F627 = 0 with regenerative ride-through F302 and auto-restart F301.

POFF: Control Under-Voltage

What it means: The control power supply (5, 15 or 24 V DC) is low. On the E3 it is the control power low warning, set slightly below the MOFF level.^{[1][2][3][4][5]}

Also on: Q9 alarm screen: DC Under-Volts. If it persists, the P9 trips with UP2.

Likely causes

• Defective control board
• Excessive load on the control power supply
• Low input voltage

First checks, in this order

1. Check the input voltage.
2. Remove or reduce external loads on the drive's 24 V supply and check again.
3. If it stays, the control board needs service.

UP2: Control Power Under-Voltage

What it means: P9 trip: undervoltage at the 5, 15 or 24 V DC control supply.^[2][5]

Also on: G7 fault screen: Control Power Undervoltage.

Likely causes

• Low three phase input voltage
• Control supply problem or excessive load on it

First checks, in this order

1. Measure the input voltage.
2. Check loads on the control supply terminals.
3. If it repeats with normal input voltage, contact TIC Customer Support.

EF2: Ground fault

What it means: Current is leaking to ground in the output cable or the motor (on S15 also in the braking resistor). On the E3, EF2 is the hardware-detected earth fault (ZCT).^{[1][2][3][4][5][6][7][8]}

Also on: G7 fault screen: Earth Fault. Q9 fault screen: Ground Fault.

Likely causes

• Motor or cable insulation failure
• Moisture giving a path to ground
• Ground fault in the braking resistor (S15)
• Very fast acceleration or deceleration with some motors (AS3)
• Drives fed from AC and linked on a common DC bus (S15 nuisance trip)

First checks, in this order

1. Disconnect the motor leads from the drive and megger the motor and cable.
2. Look for moisture in the motor, conduit or junction boxes.
3. Check that the drive chassis and motor are grounded, and keep control wiring away from power wiring.
4. AS3: increase ACC and dEC times.
5. S15 on a common DC bus fed from AC: set f614 to 0 (disabled).

EF1: Ground fault

What it means: Current to ground detected. On the E3, EF1 is the software-detected earth fault (sensed through the current sensors, HCT); P9 and Q9 Plus list EF1 and EF2 together as Ground Fault.^[1][4][5]

Also on: G7 fault screen: Earth Fault. Q9 fault screen: Ground Fault.

Likely causes

• Motor or cable insulation failure
• Moisture
• Loose or mis-wired ground

First checks, in this order

1. Megger the motor and cable with the leads disconnected from the drive.
2. Check the ground connections at drive and motor.
3. E3: noise suppressors on starter coils on the same line, or an RF/EMI filter, can stop nuisance trips.

EPHI: Input phase failure

What it means: One phase of the main input supply is missing or low.^{[2][3][4][5][6][7][8]}

Also on: G7 fault screen: Input Phase Loss. Q9 fault screen: Input Phase.

Likely causes

• Blown fuse, open breaker pole or loose input connection
• Main circuit capacitors worn and losing capacitance (S15, nC3)

First checks, in this order

1. Measure all three input voltages at R, S and T.
2. Check fuses, breaker and terminal tightness.
3. Have the main circuit capacitors checked on an older drive.
4. Detection is set by F608.

EPHO: Output phase failure

What it means: One output phase to the motor is open or carries too little current.^{[2][3][4][5][6][7][8]}

Also on: G7 fault screen: Output Phase Loss. Q9 fault screen: Output Phase.

Likely causes

• Open or loose U, V or W connection, or an open output contactor
• Motor impedance too high, or motor current very small (under about 8% of rated on AS3)
• Motor still rotating at start (AS3)

First checks, in this order

1. Check the output wiring, contactors and motor connections on all three phases.
2. Check output phase failure detection F605.
3. Start only after the motor has stopped (AS3).

E: Emergency off

What it means: The drive received an emergency off: the STOP/RESET key was pressed (twice on most models) while running from terminals or communications, an input terminal set to emergency off opened, or a command came over communications.^{[1][2][3][4][5][6][7][8]}

Also on: G7 shows EMG as an alarm and Emergency Off on the fault screen. Q9 fault screen: Emergency Off.

Likely causes

• STOP/RESET pressed twice at the keypad
• Emergency off input terminal activated
• Emergency off command over communications

First checks, in this order

1. Find out what issued the emergency off.
2. Release the emergency off signal, then reset the drive.
3. On Q9 Plus and P9, F603 sets the stopping method used by emergency off.

ERR5: Communication error

What it means: Communication with the external controller timed out or was lost. Names: Communication error (S15, P9), Remote control error (nC3), Communication time-out (RS485) (AS3), Communication interruption error (E3).^{[1][2][5][6][7][8]}

Also on: G7 fault screen: Communication Error. Q9 and Q9 Plus report communication problems as CM1 or CM2 alarms.

Likely causes

• Master (PLC or HMI) stopped polling
• Broken or loose communication cable
• Wrong communication settings

First checks, in this order

1. Check the master device and the communication cable and connectors.
2. Check the drive communication settings (AS3 section 6.38.1; E3 Item 286 COMMUNICATION SELECTION and the RS485 board jumpers J1 to J3).
3. On S15 and nC3 a blinking t (communication pre-alarm) warns before this trip; the time-out is set with f803.

ERR8: Option unit fault

What it means: An option board, usually a communication card, failed, lost its connection or timed out. Names: Optional unit fault 1 (S15), Option Device Fault (P9), Net Card Err (Q9 Plus), Option PCB error (E3), Communication time-out (option) (AS3).^{[1][2][3][4][5][6][8]}

Also on: G7 fault screen: Option Fault. Q9 fault screen: Net Card Err.

Likely causes

• Option board not seated or connector loose
• Option board removed after the drive was set up with it (E3)
• Wrong option or network settings
• Network or master problem (AS3 time-out)

First checks, in this order

1. Power down, reseat the option board and its connectors, and secure it with stand-offs.
2. Check the option settings and the network wiring.
3. Follow the option board manual for its own status LEDs.

CM1 / CM2: Comm1 Error / Comm2 Error

What it means: Communication alarm on the EOI. On G7 and P9, CM1 is an internal communication error and CM2 an external one; Q9 Plus lists CM1 as Comm Error and CM2 as Comm Error 2.^[2][3][4][5]

Also on: Q9 alarm screen: Comm Error, Comm Error 2.

Likely causes

• Communication settings wrong
• Cable not connected or damaged
• Drive programmed incorrectly for the network

First checks, in this order

1. Check the communication cables and connectors.
2. Check the communication parameters in the drive and the master.

E-18: Analog input break detection fault

What it means: The analog speed or process signal dropped below the broken wire level set in F633. Names: Analog input break detection fault (S15), Analog In Loss (Q9 Plus), Analog (Terminal) Input Loss (P9), Analog input disconnecting (AS3).^{[3][4][5][6][7][8]}

Also on: Q9 fault screen: Analog in Loss. S15 and AS3 can show A-18 as a warning instead, depending on settings.

Likely causes

• Broken or loose signal wire, or the source device off
• F633 detection level set too high
• Overcurrent on the P24 supply (Q9 Plus, P9)
• Terminal board failure (P9)

First checks, in this order

1. Measure the signal at the analog terminal (VIC on S15, VI on nC3, II on AS3).
2. Check the signal wiring for breaks.
3. Check the F633 setting.
4. Check the load on the P24 terminal.

OT: Over-torque trip

What it means: Torque stayed above the over-torque detection level (F616 or F617) for longer than F618 while running.^{[1][2][3][4][5][6][7][8]}

Also on: G7 fault screen: Overtorque. Q9 fault screen: Over-Torque. AS3 displays it as Ot.

Likely causes

• Jammed or obstructed load
• Detection level set too low
• Drive not matched to the application

First checks, in this order

1. Check the driven machine.
2. Check F615 (over-torque trip selection) and the levels F616, F617 and time F618.
3. E3: check Item 190 OVERTORQUE TRIP LEVEL.

UC: Low-current operation fault

What it means: Output current fell below the low current level (F611) for longer than the detect time while running, for example a lost load or a disconnected motor. It trips only when low current trip (F610) is enabled.^{[1][2][3][4][6][7][8]}

Also on: G7 fault screen: Low Current. Q9 fault screen: Low-Current. On G7 and P9, UC is also an Undercurrent alarm.

Likely causes

• Load lost or uncoupled
• Motor phase disconnected
• Detection level set too high

First checks, in this order

1. Check the load and the coupling.
2. Check F610 (enable) and the levels F609, F611 and F612; on the E3, Items 186 and 187.
3. Contact your Toshiba distributor if the settings are correct.

ETN / ETN1 / ETN2 / ETN3: Auto-tuning error

What it means: Motor auto-tuning could not finish because the measured motor did not match the settings or the conditions were wrong.^{[1][2][3][4][5][6][7][8]}

Also on: G7 fault screen: Autotune Error. Q9: Autotuning Err.

Likely causes

• Motor nameplate data entered wrong (vL, vLv, F405, F415, F417)
• Motor much smaller than the drive (2 frame sizes or more)
• Motor not connected, output contactor open, or main power off
• Motor rotating during tuning
• Output cable too thin or too long, or a non three phase load

First checks, in this order

1. Enter the motor nameplate data and run auto-tuning again with the motor stopped.
2. Check that the motor is connected and the output contactor closes.
3. S15 and nC3: set f416 to 70% of its value and tune again, or set f400 = 1.
4. E3: try a different inertia setting in Item 353; tune with the motor at running temperature.

ETYP: Inverter type error

What it means: The drive type data in the control board does not match the power section, usually after a board was replaced or the data was corrupted.^{[1][2][3][4][5][6][7][8]}

Also on: G7 fault screen: Typeform Error. Q9: ASD Type Error.

Likely causes

• Control or gate driver board replaced
• Data error inside the drive

First checks, in this order

1. AS3: set tyP = 6 (initialize typeform). E3: set Item 310 STANDARD SETTING MODE SELECTION (typ) to option 7.
2. If the trip repeats, contact your Toshiba distributor.

EEP1: EEPROM fault 1

What it means: Writing data to the parameter memory (EEPROM) failed.^{[1][2][3][4][5][6][7][8]}

Also on: G7 fault screen: EEPROM Fault. Q9: EEPROM Write Err.

Likely causes

• EEPROM write error
• Electrical noise from wiring faults (E3)

First checks, in this order

1. Switch power off and on again.
2. E3: check for noise sources such as CC tied to ground or an external 10 V source on PP.
3. If the trip returns, contact your Toshiba distributor.

EEP2 / EEP3: EEPROM fault 2 / EEPROM fault 3

What it means: The drive could not read its parameter memory. EEP2 also appears if a typ (default setting) operation was interrupted by a power-off; EEP3 means the EEPROM is defective or a read failed. E3 lists only EEP2.^{[1][2][3][4][5][6][7][8]}

Also on: Q9 fault screen: Ctrl Read Err or Main Read Err. G7 fault screen: EEPROM Data Fault or Main Board EEPROM Fault.

Likely causes

• typ operation interrupted by power loss
• EEPROM read error
• Defective EEPROM

First checks, in this order

1. Switch power off and on, then repeat the typ operation.
2. If the trip returns, contact your Toshiba distributor.

ERR2 / ERR3: Main unit RAM fault / Main unit ROM fault

What it means: The control board RAM (ERR2) or ROM (ERR3) failed its check.^{[1][2][3][4][5][6][7][8]}

Also on: G7 fault screen: RAM Fault, ROM Fault. Q9: ASD RAM Fault, ASD ROM Fault.

Likely causes

• Control board memory fault
• Electrical noise from wiring faults (E3)

First checks, in this order

1. Switch power off and on again.
2. E3: check for noise sources such as CC tied to ground or an external 10 V source on PP.
3. If it repeats, the control board needs replacement: contact your Toshiba distributor.

ERR4: CPU fault 1

What it means: The main control CPU reported a fault. On the E3 it also appears if an option ROM or option board is inserted or removed with power on.^{[1][2][3][4][5][6][7][8]}

Also on: G7 fault screen: CPU Fault. Q9: CPU Fault.

Likely causes

• Control CPU or control board fault
• Option board plugged or unplugged with power on (E3)
• Electrical noise

First checks, in this order

1. Switch power off and on; never plug or unplug options with power on.
2. Check for wiring that couples noise into the control terminals.
3. If it will not reset, contact your Toshiba distributor.

ERR6: Gate array fault

What it means: The gate array on the control side is defective or malfunctioning.^{[1][2][3][4][5][8]}

Also on: G7 fault screen: Gate Array Fault. Q9: Gate Array Fault.

Likely causes

• Defective gate array (control board)

First checks, in this order

1. Switch power off and on.
2. If it repeats, the control board needs replacement: contact your Toshiba distributor.

ERR7: Current detector fault

What it means: The output current sensing circuit is faulty. On the E3 it trips when the CPU sees current flowing while the drive is stopped.^{[1][3][4][6][8]}

Also on: Q9 fault screen: Current Err.

Likely causes

• Defective current detector
• E3: an RS232 cable plugged in with power on damaged the control board
• Electrical noise from nearby SCR equipment (E3)

First checks, in this order

1. Switch power off and on.
2. E3: an RF/EMI filter can remove noise spikes from nearby SCR rectifiers.
3. If it repeats, contact your Toshiba distributor.

ERR7: Low -Current

What it means: P9 only: the P9 fault table lists ERR7 as a low current fault tied to the low current detection settings.^[5]

Likely causes

• Low current detection level set wrong (F609 to F612)

First checks, in this order

1. Check F609 to F612 and the load.

ERR9: Remote keypad disconnection fault

What it means: The drive was started from the keypad or remote keypad and the keypad cable came off while running (S15: for 10 seconds or more). AS3 calls it Panel disconnection during run.^[6][8]

Also on: AS3 also has an A-09 Panel disconnection alarm.

Likely causes

• Keypad cable unplugged or damaged while running from the keypad

First checks, in this order

1. Check the keypad cable and connectors.
2. Press STOP before unplugging a remote keypad.
3. F731 can switch this detection off (S15, AS3).

ERR9: Flash Memory Fault

What it means: P9: internal flash memory malfunction.^[2][5]

Also on: G7 fault screen: Flash Memory Fault.

Likely causes

• Flash memory fault

First checks, in this order

1. Switch power off and on; if it repeats, make a service call.

ERR9: Option ROM error

What it means: E3 only: option ROM fault. It also appears if the drive was powered with an option ROM installed and later powered without it.^[1]

Likely causes

• Option ROM removed after first power-up with it
• Electrical noise from wiring faults

First checks, in this order

1. Reset in the normal way if the option ROM was removed on purpose.
2. Check for noise sources such as CC tied to ground or an external 10 V source on PP.

E-19: CPU communications error

What it means: Communication between the drive's control CPUs failed.^{[3][4][5][6][7][8]}

Also on: Q9 fault screen: Abnormal CPU2.

Likely causes

• Internal control board fault

First checks, in this order

1. Switch power off and on.
2. If it returns, contact your Toshiba distributor.

E-21: CPU fault 2

What it means: Control CPU fault. Names: CPU fault 2 (S15, nC3), CPU1 fault B (AS3), CPU Processing Error (P9), Stack Err (Q9 Plus).^{[3][4][5][6][7][8]}

Also on: Q9 fault screen: Stack Err.

Likely causes

• Control CPU or software processing fault

First checks, in this order

1. Switch power off and on.
2. If it returns, contact your Toshiba distributor.

E-26: CPU fault 3

What it means: The control CPU detected a fault. Names: CPU fault 3 (S15, nC3), CPU2 fault (AS3, P9), CPU Fault (Q9 Plus). S15 notes surrounding electrical noise can cause it.^{[4][5][6][7][8]}

Likely causes

• Control CPU or control board fault
• Electrical noise

First checks, in this order

1. Reset the drive and check for noise sources near the control wiring.
2. If it returns, contact your Toshiba distributor.

E-13: Over speed fault

What it means: Motor speed went beyond the allowed band around the command. With an encoder this points at the encoder; without one, at overvoltage limit action, an unstable supply or a PM motor not connected. Names: Over speed fault (S15, nC3), Speed Error (P9), Over-Speed (Q9 Plus), Abnormal speed error (AS3).^{[2][3][4][5][6][7][8]}

Also on: G7 fault screen: Over Speed. Q9 fault screen: Over-Speed.

Likely causes

• Input voltage fluctuating, or overvoltage limit raising the frequency
• Encoder wiring, setup or encoder failure
• PM motor setting (pt = 6) with no motor connected
• AS3: speed control gain too low

First checks, in this order

1. Check the input voltage; fit a braking resistor if regeneration is high.
2. Check encoder wiring and encoder settings.
3. AS3: check F622 to F624 and raise F459.
4. Connect the PM motor or change the pt setting.

E-12: Encoder loss

What it means: The drive is set for encoder (PG) feedback and is not receiving the encoder signal. Names: Encoder Loss (Q9 Plus), Encoder Signal-Loss Error (P9), PG error (AS3).^{[2][3][4][5][8]}

Also on: G7 fault screen: Encoder Loss or PG Type/Connection Error. Q9 fault screen: Encoder Loss.

Likely causes

• Encoder cable disconnected or mis-wired
• Wrong encoder supply voltage or PG settings
• Motor held at torque limit while stopped (P9)

First checks, in this order

1. Check the encoder wiring and connectors.
2. Check the PG settings (AS3: F376 PG select, F379 PG option voltage).
3. Check that the encoder works.

E-20: Over torque boost fault

What it means: The automatic torque boost is set too high for the motor, or the motor impedance is very low.^[5][6][7][8]

Also on: On P9, E-20 means V/f Control Error (torque processing error; make a service call).

Likely causes

• Automatic torque boost F402 set too high
• Motor with very small impedance

First checks, in this order

1. Lower F402.
2. Enter the motor nameplate data and run auto-tuning.

E-32: PTC fault

What it means: The motor PTC thermistor protection tripped, or the PTC circuit is open.^[6][8]

Likely causes

• Motor too hot
• PTC cable broken
• Analog input terminals assigned wrong (AS3)

First checks, in this order

1. Check the motor temperature and load.
2. Check the PTC and its cable.
3. AS3: check F645 and the analog input assignments.

E-42: Cooling fan fault

What it means: AS3 detected low cooling fan speed or a degraded fan.^[8]

Likely causes

• Fan worn out or failing
• Fan vents blocked

First checks, in this order

1. Check and clear the fan vents.
2. Have the cooling fan replaced through your Toshiba distributor.
3. F620 enables or disables this detection.

SOUT: Step-out (for PM motor drive only)

What it means: A permanent magnet motor lost synchronism with the drive.^{[3][4][5][6][8]}

Also on: Q9 fault screen: Step-Out (PM).

Likely causes

• Motor shaft locked
• One output phase open
• Impact load or very fast acceleration or deceleration
• DC braking used with step-out detection on (S15)

First checks, in this order

1. Free the motor shaft.
2. Check the cables between drive and motor.
3. Lengthen the acceleration and deceleration times.
4. S15: turn step-out detection off when using DC braking, or use servo lock instead. AS3: see F911.

PRF: Safe torque off error

What it means: Fault in the safe torque off (STO) circuit. AS3 also trips when the two STO inputs (STOA, STOB) disagree.^[6][8]

Also on: AS3 calls it STO circuit fault.

Likely causes

• STO circuit fault
• AS3: wiring or loose screws on STOA or STOB

First checks, in this order

1. Check the STO wiring and terminal screws.
2. If it repeats after a power cycle, contact your Toshiba distributor.

PRA: STO signal OFF

What it means: The safe torque off input is open, so the drive will not run. AS3 lists it as STO activated.^[6][8]

Likely causes

• STO circuit open or STO input voltage low
• 24 V terminal overloaded (S15: over 100 mA; AS3: 200 mA maximum)
• Control terminal block not fitted properly
• Surge absorption diode on output terminals wired with the wrong polarity
• AS3: slide switch SW1 set to PLC with no 24 V supplied

First checks, in this order

1. If STO is not used, close the STO circuit (the shorting bar is fitted at the factory).
2. Check the load on the 24 V terminal.
3. Refit the control terminal block.
4. Check the polarity of any surge absorption diodes.
5. AS3: if PrA appears during run, turn the run command off once.

OC1P / OC2P / OC3P: Overcurrent in DC section during acceleration / deceleration / run

What it means: E3: overcurrent detected in the DC section while accelerating (OC1P), decelerating (OC2P) or at constant speed (OC3P). The E3 troubleshooting chapter handles them like OC1, OC2 and OC3.^[1][4]

Also on: Q9 Plus lists OC1P, OC2P and OC3P together with OC1, OC2 and OC3 (Over-Current Acc, Dec, Run).

Likely causes

• Acceleration or deceleration time too short
• Phase to phase short
• Jammed machine or brake applied
• Voltage boost too high

First checks, in this order

1. Check for phase to phase shorts.
2. Lengthen ACC1 or DEC1, or lower voltage boost VB1.
3. Check the machine and brake.

OC1P / OC2P / OC3P: Overheat During Acceleration / Deceleration / Run

What it means: P9: the drive overheated while accelerating (OC1P), decelerating (OC2P) or running (OC3P).^[5]

Likely causes

• Cooling fan not running
• Ventilation openings blocked
• Internal thermistor disconnected
• Acceleration or deceleration too short, or DC injection current too high (OC2P)
• V/f setting wrong, or drive and motor not matched to the application

First checks, in this order

1. Check the cooling fan and clear the vents.
2. Lengthen the acceleration or deceleration time.
3. Check the V/f setting and the DC injection current.

LOSS: IV analog input loss

What it means: E3 only: the frequency command comes from the IV analog input, LA15 is set to 3, and the IV signal dropped below 1 V.^[1]

Likely causes

• Broken or disconnected IV signal wire
• Signal source off

First checks, in this order

1. Measure the IV input voltage.
2. Check the signal wiring and the LA15 setting.

AbFL: Low Suction/No Flow Cut Off

What it means: Pump protection: the drive is running but the pump produces no flow. It can be set as an alarm or a trip (F450).^[4][5]

Likely causes

• Loss of suction pressure or a closed pump discharge valve
• Pump cavitation
• Discrete input set to Low Suction/No Flow Protection activated
• Run time at the upper limit frequency reached the F484 setting

First checks, in this order

1. Check suction pressure, valves and the pump.
2. Check the discrete input wired to the no-flow switch.
3. Check F450 and F484.

OFF: ST terminal OFF

What it means: The standby (ST) input is open, so the drive will not run. The display shows OFF.^[1][6][7][8]

Also on: AS3 lists it as Standby OFF.

Likely causes

• ST to CC (or P24) circuit open
• Coast stop input (FRR) closed (S15, nC3)

First checks, in this order

1. Close the circuit between CC (or P24) and the terminal assigned to ST.
2. Open the FRR (coast) input.
3. S15: check always active functions f110.

C: Overcurrent pre-alarm

What it means: Current is at or above the overcurrent stall prevention level. The letter blinks alternately with the frequency and the drive keeps running.^[1][6][7][8]

Also on: E3 prints it as lowercase c. AS3 shows an overcurrent pre-alarm with the same meaning.

Likely causes

• Load near the drive current limit
• Short acceleration or deceleration time

First checks, in this order

1. Treat it like OC1 to OC3: lengthen ramps and check the load.
2. Check stall prevention level F601.

P: Overvoltage pre-alarm

What it means: DC bus voltage is at or above the overvoltage stall prevention level, or rising sharply. The drive keeps running.^[1][6][7][8]

Also on: E3 prints it as lowercase p. AS3 shows an overvoltage pre-alarm with the same meaning.

Likely causes

• Regeneration during deceleration
• High or spiking input voltage

First checks, in this order

1. Treat it like OP1 to OP3: lengthen deceleration and consider a braking resistor.

L: Overload pre-alarm

What it means: The overload count has reached 50% or more of the trip value, or the power module temperature reached the pre-alarm level.^[1][6][7][8]

Also on: AS3 shows motor and inverter overload pre-alarms with the same meaning.

Likely causes

• Load or duty heavier than the drive or motor rating

First checks, in this order

1. Treat it like OL1, OL2 and OL3: reduce the load, lengthen ramps and check motor thermal settings.

H: Overheat pre-alarm

What it means: The drive has reached its overheat pre-alarm temperature.^[1][6][7][8]

Also on: AS3 shows an overheat pre-alarm with the same meaning.

Likely causes

• Fan, airflow or ambient problems

First checks, in this order

1. Treat it like OH: check the fan, vents and ambient temperature.

T: Communication pre-alarm

What it means: Communication has been lost for at least the time set in f803; it comes before an ERR5 trip. On the E3, lowercase t is the option board communication alarm.^[1][6][7][8]

Also on: AS3 shows a communication pre-alarm (RS485, option) with the same meaning.

Likely causes

• Communication link interrupted

First checks, in this order

1. Treat it like ERR5: check the master, cable and settings.

OC: Over-Current

What it means: EOI alarm: output current is above the F601 stall prevention level. If it continues, an OC trip can follow.^[2][3][4][5]

Also on: Q9 alarm screen: Over-Current. It is normal while Automatic Accel/Decel is active (Q9 Plus).

Likely causes

• Short acceleration or deceleration time
• Jammed machine or brake engaged
• Voltage boost too high
• Output wiring fault or failed IGBT

First checks, in this order

1. Lengthen F009 and F010.
2. Check the machine and brake.
3. Disconnect the motor and retry to separate drive and motor faults.

OP: Over-Voltage

What it means: EOI alarm: DC bus voltage is above specification. P9 notes it is normal for OP to flash during deceleration when Automatic Acc/Dec (F000) is used.^[2][3][4][5]

Also on: Q9 alarm screen: DC Over-Volts.

Likely causes

• Deceleration too short or the system regenerating
• Input voltage high or spiking
• Over-voltage stall or braking resistor function switched off

First checks, in this order

1. Lengthen F010.
2. Check the braking resistor setup.
3. Check the input voltage.

OLI: ASD Overload

What it means: EOI alarm: the load is above what the drive can carry and an OL1 trip may follow.^[2][3][4][5]

Also on: Q9 Plus prints this alarm as OL1. Q9 alarm screen: ASD Overload.

Likely causes

• Excessive load
• Carrier frequency too high
• Acceleration too short or DC braking too strong
• Starting into a spinning load after a power dip

First checks, in this order

1. Reduce the load or lengthen the acceleration time.
2. Lower the carrier frequency F300.
3. Check that the drive is sized for the application.

OLM: Motor Overload

What it means: EOI alarm: the motor thermal model is building toward a motor overload trip.^[2][3][4][5]

Also on: Q9 alarm screen: Motor Overload.

Likely causes

• Motor locked or overloaded
• Long running at low speed
• V/f setting wrong

First checks, in this order

1. Check the load and motor.
2. Check motor overload settings (F600) and the V/f pattern.