LS iV5 Fault Codes List

Troubleshoot your LS iV5 high-performance vector drive with our updated guide. Learn to interpret OCT, OVT, and Encoder (ENC) trips, use DriveView for diagnostics, and reset faults.

LS iV5 Fault Codes Reference Table

Below is the complete list of protective functions and alarm codes for the iV5 series. Use this table to match the code on your LCD display with the specific diagnostic remedy.

LS Electric iV5 - Troubleshooting and Maintenance

Fault Code and Meaning	Cause and Remedy
Over Current Over Current Protection	Cause: The inverter turns off its output when the output current of the inverter flows more than 200% of the inverter rated current. Remedy: Check for short circuits, excessive load, or motor insulation failure.
Ground Fault Ground Fault Protection	Cause: A ground fault occurred and the current exceeded the internal setting value. This can occur due to low ground fault resistance. Remedy: Check output cabling and motor insulation for ground faults.
Over Voltage Over voltage protection	Cause: DC voltage of the main circuit increased higher than the rated value (200V class: 400V DC, 400V class: 820 V DC). This often happens when the motor decelerates (regenerative energy) or due to a surge voltage in the power supply. Remedy: Check input power for surges; consider increasing deceleration time or using a braking resistor.
Low Voltage Low Voltage Protection	Cause: DC voltage dropped below the detection level (200V class: 180Vdc, 400V class: 360Vdc). Insufficient torque or motor overheating can occur if input voltage drops. Remedy: Check input power supply voltage and wiring connections.
Over Load Overload Protection	Cause: The output current flowed at 180% of the inverter rated current for more than the current limit time (S/W). Remedy: Reduce load; check motor capacity matches inverter capacity.
Inv OLT Inverter Overload	Cause: The rated current of the inverter flowed more than regulation level (150% for 1 minute; inversely proportional to time). Remedy: Check load rating and duty cycle.
InvOver Heat Heat Sink Over Heat	Cause: The heat sink overheated due to a damaged cooling fan or foreign substance in the cooling fan (detected by heat sink temperature). Remedy: Check cooling fan for damage or blockages; clean heat sink.
OHD Open Heat Sink Over Heat (OHD)	Cause: OHD is opened and the heat sink is overheated. (Note: Only applies to SV2800 ~ 3750iV5). Remedy: Check thermal sensor continuity and cooling system.
InvThem OP Inverter NTC Thermistor Open	Cause: The inverter NTC Thermistor is open. Remedy: Contact service/support; internal hardware check required.
MotOver Heat Motor overheat	Cause: Motor temperature exceeded 150°C. Output stopped to protect motor. Remedy: Check motor cooling, load factor, and operating environment.
MotThem Err Motor Thermistor Error	Cause: Error in the Thermistor that measures motor temperature (e.g., NTC open). Remedy: Check motor thermistor wiring and sensor health.
E-Thermal Electronic Thermal	Cause: Internal electronic thermal calculation determined motor overheating. Overload capacity: 150% for 1 min. Note: Inverter cannot protect multi-pole or multiple motors effectively with this function alone. Remedy: If driving multiple motors, consider installing external thermal relays for each motor.
External-B External fault B	Cause: User triggered the external fault signal to turn off output. Remedy: Check external input source/switch assigned to External Fault B.
Arm Short / Arm Short-DB IGBT Short	Cause: Inverter output stopped because IGBT Arm short or output short occurred. (Arm Short-DB applies to SV110~220iV5). Remedy: Check output wiring for shorts; internal IGBT may be damaged.
Fuse Open Fuse Open	Cause: Fuse opened to protect wiring from short currents (usually implies main circuit IGBT issue). Remedy: Do not replace fuse immediately; check main circuit IGBT and wiring for shorts.
Encoder Err Encoder Error	Cause: 1) Encoder signal fault occurred (Hardware). 2) Discord of detection time standard of motor error of PAR-14 (Software). Remedy: Check encoder wiring, power, and PAR-14 settings.
BX BX protection (Instant Cut Off)	Cause: Used for emergency stop. Output turns off instantly when BX terminal is ON. Returns to operation when BX is OFF. Remedy: Check status of the BX terminal input. Take caution when using this function.
Over Speed Motor overspeed	Cause: Motor is rotating over 120% of its rated speed. Remedy: Check load inertia, brake settings, and speed command parameters.
COM Error / CPU Error Communication Error	Cause: Inverter cannot communicate with the keypad. Remedy: Check keypad connection cable and seating.
HW- Diag H/W Error	Cause: CPU has a problem; inverter blocks IGBT gating signals. Remedy: Cycle power. If fault persists, contact service (CPU/Control board failure).
FAN Lock FAN Lock	Cause: The inverter detected a Fan Lock condition. (Only comes under SV2800~3750iV5). Remedy: Inspect cooling fans for debris or mechanical failure.
Enc Power Encoder PowerError	Cause: Error in Encoder power source. (Only comes under SV2800~3750iV5). Remedy: Check encoder power supply voltage and wiring.
Input PO Input Phase-open	Cause: Power from one phase among the 3-phase input is discontinued at normal load state. Remedy: Check input power lines, fuses, and circuit breakers.
Output PO Output Phase-open	Cause: Inverter detected no-output current (open phase on output). Remedy: Check motor wiring and motor windings for continuity.
FAN/MC PWR AC FAN and M/C Power Error	Cause: AC220V is not supplied to AC FAN and M/C. (Applicable to 30 ~ 160 kW). Remedy: Check auxiliary AC220V power supply to fans and magnetic contactors.
FAN PWR AC FAN Power Error	Cause: AC220V is not supplied to AC FAN and M/C. Remedy: Check auxiliary AC power supply.

 

How to Read iV5 Faults via LCD Keypad & DriveView

The iV5 offers deep diagnostic visibility, which is essential for precision motion control. In 2026, the standard maintenance protocol involves using the LCD interface or LS Electric’s diagnostic software:

• Trip History (PRT Group): The iV5 maintains a non-volatile log of the last 5 trips. Navigate to the PRT (Protection) group on the LCD keypad to view the history.
• Status at Trip: By selecting a trip from the history and pressing the ENT key, the iV5 provides a “snapshot.” This includes the motor speed (RPM), current (A), DC link voltage (V), and the specific time the fault occurred.
• DriveView 7/9: For high-precision applications like elevators, connecting your PC to the iV5 via the RS485 or Option card allows you to use DriveView. This is critical for monitoring ENC (Encoder) pulses and Torque waveforms to see if a trip is caused by mechanical slippage or electrical noise.

General Troubleshooting Steps for Vector Drives

Because the iV5 is often used in “Closed Loop” systems, perform these checks before resetting a major fault:

1. Encoder Check (ENC): If you receive an ENC fault, verify the encoder wiring and coupling. Even a slight vibration or loose shielding can cause a loss of feedback, triggering an immediate safety trip.
2. Overcurrent (OCT): Common in hoist and lift applications. Check the mechanical brake timing. If the drive attempts to run before the brake is fully released, an OCT trip will occur.
3. Ground Fault (GFT): The iV5 features highly sensitive leakage protection. Check for moisture in the motor terminals or breakdown in cable insulation, especially in older installations.

Frequently Asked Questions (FAQ)

Q: What is the difference between “OCT” and “IOL” on the iV5?

A: OCT (Overcurrent Trip) is an instantaneous shutdown caused by a massive current spike (short circuit or jam). IOL (Inverter Overload) is a time-based trip, meaning the drive has been running above its rated current for too long and needs to cool down.

Q: How do I reset a fault on the LS iV5?

A: Once the fault is cleared, you can reset the drive by:

• Pressing the RESET key on the graphical LCD keypad.
• Activating the RST digital input terminal on the control board.
• Cycling the main input power (Wait until the DC bus discharge light is off before restarting).

Q: Why does my drive show “LVT” even when power is on?

A: LVT (Low Voltage Trip) means the DC bus voltage is below the minimum threshold. This can be caused by a blown input fuse, a dropped phase, or a faulty soft-charge contactor within the drive. Check your 3-phase input voltage immediately.

Q: What is “Auto-Tuning” (TUNE) and why is it failing?

A: The iV5 requires an accurate motor model to perform vector control. If TUNE fails, check that the motor nameplate data (HP, Amps, RPM) is entered correctly and that the motor is disconnected from the load if performing a Rotational Tune.